Nutritional advice

Objectives:
Previous meta-analysis studies have indicated inverse associations between some carotenoids and risks of metabolic syndrome, cardiovascular disease, cancer and all-cause mortality. However, the results for associations between carotenoids and type 2 diabetes (T2D) remain inconsistent and no systematic assessment has been done on this topic. Therefore, this review article (meta-analysis) has been conducted.

Do higher dietary intakes and circulating concentrations of carotenoids reduce risk of type 2 diabetes?

Study design:
This review article included 13 studies.

Results and conclusions:
The investigators found for the the highest versus the lowest categories of dietary intake of β-carotene a significantly reduced risk of 22% for type 2 diabetes [pooled RR = 0.78, 95% CI = 0.70 to 0.87, I2 = 13.7%, n = 6].
This significantly reduced risk was also found for total carotenoids (n = 2), α-carotene (n = 4), and lutein/zeaxanthin (n = 4), with pooled RRs ranging from 0.80 to 0.91, whereas no significant associations were observed for β-cryptoxanthin and lycopene.

The investigators found for the the highest versus the lowest categories of circulating concentration of β-carotene a significantly reduced risk of 40% for type 2 diabetes [pooled RR = 0.60, 95% CI = 0.46 to 0.78, I2 = 56.2%, n = 7].
This significantly reduced risk was also found for total carotenoids (n = 3), lycopene (n = 4), and lutein (n = 2), with pooled RRs ranging from 0.63 to 0.85, whereas no significant association was found for circulating concentrations of α-carotene and zeaxanthin when comparing extreme categories.

The investigators found dose-response analysis indicated that nonlinear relations were observed for circulating concentrations of α-carotene, β-carotene, lutein and total carotenoids [all p-nonlinearity 0.05], but not for other carotenoids or dietary exposures.

The investigators concluded that higher dietary intakes and circulating concentrations of total carotenoids, especially β-carotene, are associated with a lower risk of type 2 diabetes. More studies are needed to confirm the causality and explore the role of foods rich in carotenoids in prevention of type 2 diabetes.

Original title:
Dietary Intake and Circulating Concentrations of Carotenoids and Risk of Type 2 Diabetes: A Dose-Response Meta-Analysis of Prospective Observational Studies by Jiang YW, Sun ZH, [...], Pan A.

Link:
https://pubmed.ncbi.nlm.nih.gov/33979433/

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Objectives:
Although current guidelines recommend reduction of salt intake in patients with diabetes, the benefits of reducing salt intake in people with type 2 diabetes mellitus (T2DM) lack clear evidence. Therefore, this review articles has been conducted.

Does dietary sodium restriction causally reduce blood pressure in patients with type 2 diabetes mellitus (T2DM)?

Study design:
This review article included 8 RCTs with 10 trials (7 cross-over and 3 parallel designs).
No publication bias was found from Begg's and Egger's tests.

Results and conclusions:
The investigators found compared with ordinary sodium intake, dietary sodium restriction significantly decreased 24-hour urine sodium level [WMD = -38.430 mmol/24h, 95% CI = -41.665 mmol/24h to -35.194 mmol/24h].

The investigators found dietary sodium restriction significantly lowered systolic blood pressure [WMD = -5.574 mm Hg, 95% CI = -8.314 to -2.834 mm Hg, I2 = 0.0%] and diastolic blood pressure [WMD = -1.675 mm Hg, 95% CI = -3.199 to -0.150 mm Hg, I2 = 0.0%].

The investigators concluded that dietary sodium restriction causally reduces systolic blood pressure and diastolic blood pressure in patients with type 2 diabetes mellitus (T2DM).

Original title:
Effect of dietary sodium restriction on blood pressure in type 2 diabetes: A meta-analysis of randomized controlled trials by Ren Y, Liqiang Qin L, […], Ma Y.

Link:
https://pubmed.ncbi.nlm.nih.gov/33838996/

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Salt consists of sodium and chloride. So a dietary sodium restriction means a reduction in dietary salt intake.

A diet with dietary salt restriction is a diet with maximum 0.2 grams of salt per 100 kcal.

The easiest way to follow this diet is to choose only products/meals with maximum 0.2 grams of salt per 100 kcal. These products from the supermarket contain maximum 0.2 grams of salt per 100 kcal.

However, the most practical way to follow this diet is, all your daily consumed products/meals should contain on average maximum 0.2 grams of salt per 100 kcal.
To do this, use the 7-points nutritional profile app to see if your daily diet contains maximum 0.2 grams of salt per 100 kcal.

Objectives:
Evidence regarding associations between potato consumption and type 2 diabetes (T2D) and gestational diabetes mellitus (GDM) risks is accumulating. Therefore, this review article has been conducted.

Does a high potato intake increase type 2 diabetes and gestational diabetes mellitus (diabetes mellitus during pregnancy) risk?

Study design:
This review article included 19 studies (13 for type 2 diabetes and 6 for gestational diabetes mellitus) with a total of 21,357 type 2 diabetes cases among 323,475 participants and 1,516 gestational diabetes mellitus cases among 29,288 pregnancies.

Results and conclusions:
The investigators found meta-analysis showed a significantly increased risk of 19% [RR = 1.19, 95% CI = 1.06 to 1.34] for type 2 diabetes for total potato intakes among Western populations.

The investigators found meta-analysis showed a significantly increased risk of 8% [RR = 1.08, 95% CI = 1.00 to 1.16] for type 2 diabetes for baked/boiled/mashed potato intakes among Western populations.

The investigators found meta-analysis showed a significantly increased risk of 33% [RR = 1.33, 95% CI = 1.03 to 1.70] for type 2 diabetes for French fries/fried potato intakes among Western populations.

The investigators found dose-response meta-analysis demonstrated a significantly increased type 2 diabetes risk by 10% [95% CI = 1.07 to 1.14, p for trend 0.001], 2% [95% CI = 1.00 to 1.04, p for trend = 0.02] and 34% [95% CI = 1.24 to 1.46, p for trend 0.001] among Western populations for each 80 g/day (serving) increment in total potato, unfried potato and fried potato intakes, respectively.

The investigators found dose-response meta-analysis demonstrated a significantly increased gestational diabetes mellitus risk by 22% [95% CI = 1.06 to 1.42, p for trend 0.007] among Western populations for each 80 g/day (serving) increment in total potato intakes.

The investigators found dose-response meta-analysis demonstrated a significantly increased gestational diabetes mellitus risk by 26% [95% CI = 1.07 to 1.48, p for trend = 0.006] among Western populations for each 80 g/day (serving) increment in unfried potato intakes.

The investigators concluded that higher potato intake (at least 80g per day) is associated with higher type 2 diabetes risk among Western populations. The positive relationship presents a significant dose-response manner. Wisely controlled potato consumption may confer potential glucometabolic benefits.

Original title:
Dietary potato intake and risks of type 2 diabetes and gestational diabetes mellitus by Guo F, Zhang Q, [...], Ma L.

Link:
https://pubmed.ncbi.nlm.nih.gov/34130021/

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Objectives:
Does vitamin C supplementation improve triglyceride and cholesterol levels in patients with type 2 diabetes mellitus?

Study design:
This review article included 15 studies with 872 participants.

Results and conclusions:
The investigators found, findings from 15 studies indicated that vitamin C supplementation significantly decreased triglyceride (TG) levels [WMD= -16.48 mg/dL, 95% CI = -31.89 to -1.08, p 0.001] and total cholesterol (TC) levels [WMD = -13.00 mg/dL, 95% CI = -23.10 to -2.91, p 0.001] in patients with type 2 diabetes mellitus.

The investigators found, however, vitamin C supplementation failed to improve LDL (bad cholesterol) and HDL cholesterol (good cholesterol) levels. 

The investigators found the meta-regression analysis suggested that lipid profile improvement was affected by duration of vitamin C treatment.

The investigators found dose-response analysis showed that vitamin C supplementation changed LDL cholesterol significantly based on vitamin C dose.

The investigators concluded that vitamin C supplementation improves lipid profile via decreases in triglyceride and total cholesterol levels in patients with type 2 diabetes mellitus. It appears that vitamin C supplementation is more beneficial to lipid profile in long-term vs. short term interventions.

Original title:
Does vitamin C supplementation exert profitable effects on serum lipid profile in patients with type 2 diabetes? A systematic review and dose-response meta-analysis by Namkhah Z, Ashtary-Larky D, […], Asbaghi O.

Link:
https://pubmed.ncbi.nlm.nih.gov/33984490/

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Objectives:
Does spirulina supplementation improve glycemic related markers (like, fasting blood glucose, post prandial blood sugar and HbA1c levels) and lipid profile (like, triglyceride and cholesterol levels) among type 2 diabetes patients?

Study design:
This review article included 8 RCTs (9 arms).

Results and conclusions:
The investigators found, spirulina supplementation significantly reduced fasting blood glucose levels [-17.88 mg/dL, 95% CI = -26.99 to -8.78, I2 = 25%] among type 2 diabetes patients.

The investigators found, spirulina supplementation significantly reduced triglyceride levels [-30.99 mg/dL, 95% CI = -45.20 to -16.77, I2 = 50%] among type 2 diabetes patients.

The investigators found, spirulina supplementation significantly reduced total cholesterol levels [-18.47 mg/dL, 95% CI = -33.54 to -3.39, I2 = 73%] among type 2 diabetes patients.

The investigators found, spirulina supplementation significantly reduced LDL cholesterol (bad cholesterol) levels [-20.04 mg/dL, 95% CI = -34.06 to -6.02, I2 = 75%] among type 2 diabetes patients.

The investigators found, spirulina supplementation significantly reduced VLDL cholesterol levels [-6.96 mg/dL, 95% CI = -9.71 to -4.22, I2 = 33%] among type 2 diabetes patients.

The investigators found, spirulina supplementation significantly increased HDL cholesterol (good cholesterol) levels among type 2 diabetes patients.

The investigators found no significant effect on HbA1C or post prandial blood sugar among type 2 diabetes patients following spirulina supplementation.

The investigators concluded that spirulina supplementation has beneficial effects on fasting blood glucose and blood lipid profiles among type 2 diabetes patients.

Original title:
The effect of spirulina on type 2 diabetes: a systematic review and meta-analysis by Hatami E, Ghalishourani SS, […], Mansour-Ghanaei F.

Link:
https://pubmed.ncbi.nlm.nih.gov/34178867/

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Objectives:
Does grapes/grape products supplementation improve glycemic indices (like HOMA-IR, Hb1Ac and fasting insulin level) in adults or in other words, does eating grapes or grape products causally improve glycemic indices in adults?

Study design:
This review article included 29 RCTs with a total of 1,297 participants.

Results and conclusions:
The investigators found, overall, the grapes/grape products supplementation significantly reduced homeostatic model assessment of insulin resistance (HOMA-IR) [WMD = -0.54, 95% CI = -0.91 to -0.17, p = 0.004] in adults.   
Significantly because the calculated p-value of = 0.004 was less than the p-value of 0.05.

The investigators found, however, the grapes/grape products supplementation did not affect fasting insulin levels [WMD = -0.90 μIU/mL, 95% CI = -1.04 to 2.84, p = 0.362] and hemoglobin A1c (Hb1Ac) percentage [WMD = 0.00%, 95% CI = -0.10 to 0.11, p = 0.916] in the main analyses.
Did not affect because the calculated p-value of 0.916 was larger than the p-value of 0.05.

The investigators concluded that the grapes/grape products supplementation reduces homeostatic model assessment of insulin resistance (HOMA-IR) in adults. Further, large-scale RCTs with longer duration are required to confirm these results.

Original title:
The effect of grapes/grape products on glycemic response: A systematic review and meta-analysis of randomized controlled trials by Moodi V, Abedi S, […], Miraghajani M.

Link:
https://pubmed.ncbi.nlm.nih.gov/33893683/

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Homeostatic model assessment of insulin resistance (HOMA-IR) is a method for assessing β-cell function and insulin resistance (IR) from basal (fasting) glucose and insulin or C-peptide concentrations. HOMA-IR is an indicator of insulin resistance in diabetic patients. The higher the value, the more resistant you are to insulin. Diabetic patients often have a high HOMA-IR value.

Objectives:
Does chromium supplementation improve lipid profile (serum levels of triglyceride and cholesterol) in patients with type 2 diabetes mellitus (T2DM)?

Study design:
This review article included  24 RCTs (with 28 effect sizes).

Results and conclusions:
The investigators found that chromium supplementation resulted in a significant decrease in serum levels of triglyceride (TG) in patients with type 2 diabetes mellitus [MD = -6.54 mg/dL, 95 % CI = -13.08 to -0.00, p = 0.050].
Significant means that there is an association with a 95% confidence.

The investigators found that chromium supplementation resulted in a significant decrease in serum levels of total cholesterol (TC) in patients with type 2 diabetes mellitus [WMD = -7.77 mg/dL, 95 % CI = -11.35 to -4.18, p 0.001].

The investigators found that chromium supplementation significantly increased high-density lipoprotein cholesterol (HDL cholesterol or good cholesterol) in patients with type 2 diabetes mellitus [WMD = 2.23 mg/dL, 95 % CI = 0.07 to 4.40, p = 0.043] level.

The investigators found, however, chromium supplementation did not have significant effects on low-density lipoprotein cholesterol (LDL cholesterol or bad cholesterol) in patients with type 2 diabetes mellitus [WMD = -8.54 mg/dL, 95 % CI = -19.58 to 2.49, p = 0.129] level.

The investigators concluded that chromium supplementation decreases serum levels of triglyceride (TG) and total cholesterol (TC) and increases HDL cholesterol (good cholesterol) levels in patients with type 2 diabetes mellitus. It should be noted that the lipid-lowering properties of chromium supplementation are small and may not reach clinical importance.

Original title:
Effects of chromium supplementation on lipid profile in patients with type 2 diabetes: A systematic review and dose-response meta-analysis of randomized controlled trials by Asbaghi O, Naeini F, […], Naeini AA.

Link:
https://pubmed.ncbi.nlm.nih.gov/33813266/

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Objectives:
Does L-arginine supplementation improve biomarkers (fasting blood sugar, insulin, HbA1c and HOMA-IR values) of glycemic control in adults?

Study design:
This review article included 12 randomised clinical trials (RCTs).

Results and conclusions:
The investigators found L-arginine supplementation had no significant effect on serum fasting blood sugar (FBS) [weighted mean difference (WMD) = -3.38 mg/dL, 95% CI = -6.79 to 0.04, p = 0.53], serum insulin [WMD = -0.12 Hedges' g, 95% CI = -0.33 to 0.09, p = 0.27], glycated haemoglobin A1c (HbA1c) [WMD = -0.04%, 95% CI = -0.25 to 0.17, p = 0.71] and homeostasis model assessment for insulin resistance (HOMA-IR) [WMD = -0.48, 95% CI = -1.15 to 0.19, p = 0.15].
No significant because the calculated p-value of 0.15 was larger than the p-value of 0.05.

The investigators concluded although several animal studies have proposed that L-arginine supplementation might improve blood glucose control, the present review article could not confirm this benefit in humans.

Original title:
Effects of L-arginine supplementation on biomarkers of glycemic control: a systematic review and meta-analysis of randomised clinical trials by Karimi E, Hatami E, […], Askari G.

Link:
https://pubmed.ncbi.nlm.nih.gov/33426939/

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Arginine is classified as a semiessential or conditionally essential amino acid, depending on the developmental stage and health status of the individual, that helps the body build protein. L-arginine is also found in most protein-rich foods, including fish, red meat, poultry, soy, whole grains, beans and dairy products.
 

Objectives:
Does garlic supplementation reduce adiponectin and leptin serum levels?

Study design:
This review article included 5 RCTs.

Results and conclusions:
The investigators found that garlic supplementation did not significantly affect adiponectin [Hedges's = 0.20, 95% CI = -0.06 to 0.47, p = 0.12] and leptin [Hedges's = 0.08, 95% CI = -0.26 to 0.41, p = 0.65] concentrations in comparison with placebo.

The investigators found, however, in the subgroup analysis, significantly increased serum adiponectin level was seen following garlic supplementation in trials with a mean age of participants ˂30 years [Hedges's = 0.44, 95% CI = 0.01 to 0.87, p = 0.04], the doses ˂1.5 g/day [Hedges's = 0.38, 95% CI = 0.02 to 0.71, p = 0.04] and trials with duration ≥8 weeks [Hedges's = 0.48, 95% CI = 0.08 to 0.89, p = 0.02].

The investigators concluded that ˂1.5 g/day garlic supplementation during ≥8 weeks reduces adiponectin level among participants ˂30 years.

Original title:
Systematic review and meta-analysis of randomized, controlled trials on the effects of garlic supplementation on serum adiponectin and leptin levels by Shekarchizadeh-Esfahani P, Hassani B, […], Soraya N.

Link:
https://pubmed.ncbi.nlm.nih.gov/33792129/

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Adiponectin is a fat-derived hormone that appears to play a crucial role in protecting against insulin resistance/diabetes and atherosclerosis (atherosclerosis is the dominant cause of cardiovascular disease (CVD)). Decreased adiponectin levels are thought to play a central role in the development of obesity, cardiovascular disease and type 2 diabetes in humans.

Objectives:
Previous meta-analyses, with some methodological controversies, have assessed the relation between nut consumption and type 2 diabetes (T2D) risk and pointed to contradictory results. Therefore, this review article has been conducted.

Does nut consumption reduce risk of type 2 diabetes?

Study design:
This review article included 5 prospective cohort studies and 3 cross-sectional studies.
The certainty of the evidence using NutriGrade was very low for all the exposures.

Results and conclusions:
The investigators found meta-analyses of cross-sectional studies and prospective cohort studies, comparing the highest with the lowest categories, revealed a nonsignificant association between total nut consumption and type 2 diabetes.
Nonsignificant means that there is no association with a 95% confidence.

The investigators found meta-analyses of prospective cohort studies showed that peanut butter consumption significantly reduced type 2 diabetes incidence with 13% [RR = 0.87, 95% CI = 0.77 to 0.98, I2 = 50.6%, p = 0.16], whereas no association was observed between peanuts or tree nuts and type 2 diabetes.

The investigators found there was no evidence of a linear dose-response or nonlinear dose-response gradient for total nut and peanut consumption in prospective cohort studies.

The investigators concluded peanut butter consumption may reduce type 2 diabetes incidence. May reduce because the certainty of the evidence using NutriGrade was very low.

Original title:
Nut consumption and type 2 diabetes risk: a systematic review and meta-analysis of observational studies by Becerra-Tomás N, Paz-Graniel I, […], Salas-Salvadó J.

Link:
https://pubmed.ncbi.nlm.nih.gov/33471083/

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Objectives:
Peripheral neuropathy (PN) is common in patients with diseases that are in turn associated with deficiency of the B-vitamins, and vitamin treatment has shown mixed results. Therefore, this review article has been conducted.

Does a low vitamin B level increase the risk of peripheral neuropathy?

Study design:
This review article included 46 observational studies and 7 interventional studies.

Results and conclusions:
The investigators found the presence of peripheral neuropathy was significantly associated with lowered B12 levels [1.51, 95% CI = 1.23 to 1.84, n = 34, I2 = 43.3%, p = 0.003].

The investigators found the presence of peripheral neuropathy was significantly associated with elevated methylmalonic acid levels [2.53, 95% CI = 1.39 to 4.60, n = 9, I2 = 63.8%, p = 0.005].

The investigators found the presence of peripheral neuropathy was significantly associated with elevated homocysteine levels [3.48, 95% CI = 2.01 to 6.04, n = 15, I2 = 70.6%, p 0.001].

The investigators found treatment with vitamin B1 was associated with a significant improvement in symptoms of peripheral neuropathy [5.34, 95% CI = 1.87 to 15.19, n = 3, I2 = 64.6%, p = 0.059].

The investigators found B12 treatment (vs. the comparators) showed a non-significant association with symptom improvement [1.36, 95% CI = 0.66 to 2.79, n = 4, I2 = 28.9%].

The investigators found analysis of 7 trials combined showed a non-significant higher odds ratio for improvement under treatment with the B-vitamins [2.58, 95% CI = 0.98 to 6.79, I2 = 80.0%, p 0.001].

The investigators concluded peripheral neuropathy is associated with lowered plasma vitamin B12 and elevated methylmalonic acid and homocysteine levels. Well-designed studies, especially in non-diabetes peripheral neuropathy, are needed.

Original title:
Association between neuropathy and B-vitamins: A systematic review and meta-analysis by Stein J, Geisel J and Obeid R.

Link:
https://pubmed.ncbi.nlm.nih.gov/33619867/

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Peripheral neuropathy refers to the conditions that result when nerves that carry messages to and from the brain and spinal cord from and to the rest of the body are damaged or diseased.

Increased methylmalonic acid levels are a sensitive indicator of mild vitamin B12 deficiency.
 

Objectives:
Does a low-carbohydrate diet (LCD) causally increase adiponectin concentration in adults?

Study design:
This review article included 11 RCTs with 534 participants in low-carbohydrate diet group and 513 participants in control group (group without a low-carbohydrate diet).
Proportion of carbohydrate from calorie was from 4 to 34% (4-34 En%).
Time of the follow-up varied between studies and ranged from 6 to 152 weeks.
Meta-regression analysis revealed that age [β = 0.04, p = 0.15], baseline BMI [β= -0.15, p = 0.15], time of follow-up [β = 0.01, p = 0.17], energy percentage of carbohydrates [β = 0.004, p = 0.90], energy percentage of protein [β = -0.12, p = 0.08], energy percentage of fat [β = 0.20, p = 0.61] and baseline adiponectin [β = 0.001, p = 0.97] are not sources of heterogeneity

Results and conclusions:
The investigators found low-carbohydrate diet significantly increased adiponectin concentration [0.02 µg/mL, 95% CI = 0.01 to 0.03, p 0.001].

The investigators found dose-response analysis indicated a nonlinear association between the percentage of carbohydrate and change in adiponectin level from baseline [p = 0.04].

The investigators found in subgroup analysis based on the proportion of carbohydrate from calorie, there was a significant increase in adiponectin concentration in studies that prescribed 30% of calorie from carbohydrates [0.12 µg/mL, 95% CI = 0.07 to 0.18].
In contrast, diets which consisted ≥30% of carbohydrates had no significant effect on adiponectin [0.50 µg/mL, 95% CI = -0.46 to 1.48].

The investigators concluded that a diet with 30% of calorie from carbohydrates (diet with 30 En% carbohydrates) causally increases adiponectin concentration in adults.

Original title:
Effect of low-carbohydrate diet on adiponectin level in adults: a systematic review and dose-response meta-analysis of randomized controlled trials by Shemirani F, Golzarand M, […], Mahmoudi M.

Link:
https://pubmed.ncbi.nlm.nih.gov/33455438/

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The most easy way to follow a diet with maximum 30% of calorie from carbohydrates (diet with 30 En% carbohydrates) is to choose only meals/products with maximum 30 En% carbohydrates. Check here which products contain maximum 30 En% carbohydrates. However, the most practical way to follow a diet with maximum 30 En% carbohydrates is, all meals/products that you eat on a daily basis should on average contain maximum 30 En% carbohydrates.
30 En% carbohydrates means that the total amounts of carbohydrates make up for a 30% of the total kcal of the diet.

Adiponectin is a protein hormone produced and secreted exclusively by adipocytes (fat cells) that regulates the metabolism of lipids and glucose. Adiponectin influences the body's response to insulin. Adiponectin also has antiinflammatory effects on the cells lining the walls of blood vessels.
 

Objectives:
Fish oil has been shown to reduce the risk of metabolic disorders. However, the effects of fish oil intervention on glucose metabolism and insulin sensitivity are still controversial, especially in children. Therefore, this review article has been conducted.

Do fish oil supplements (EPA + DHA) improve insulin sensitivity in children?

Study design:
This review article included 13 RCTs with 567 children in placebo group (group without fish oil supplements) and 565 in fish oil group (intervention group).

No heterogeneity was found for the pooled and subgroup analyses.

Results and conclusions:
The investigators found compared with the placebo group, fish oil intervention had beneficial effects on insulin sensitivity in the pooled analysis [WMD = -0.219, 95% CI = -0.392 to -0.046, p = 0.013].

These beneficial effects were also found in subgroup analyses, when the fish oil intervention period was short-term (≤6 months) low dose (eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) dose 1.5 g/day) and high ratio (eicosapentaenoic acid to docosahexaenoic acid ≥1).

The investigators concluded fish oil supplements, especially 1.5 g/day EPA + DHA during 6 months, improve insulin sensitivity in children.

Original title:
Effect of Fish Oil on Insulin Sensitivity in Children: A Systematic Review and Meta-Analysis of Randomized, Controlled Trials by Hou M, Zhou W, [...], Lv H.

Link:
https://pubmed.ncbi.nlm.nih.gov/33388274/

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Objectives:
Does type 1 diabetes mellitus (T1DM) decrease bone mineral density (BMD) in children and adolescents?

Study design:
This review article included 9 cross-sectional studies with a total of 1,522 children and adolescents.

Funnel plot and the Egger test did not reveal significant publication bias.

Results and conclusions:
The investigators found a significant decrease in bone mineral density Z-score in the whole body [pooled WMD = -0.47, 95% CI = -0.92 to -0.02, I2 = 80.2%] and lumbar spine [pooled WMD = -0.41, 95% CI = -0.69 to -0.12, I2 = 80.3%] in children and adolescents with type 1 diabetes mellitus, which was consistent in published studies from Asia and South America, but inconsistent in the North America and Europe.
Sensitivity analyses did not modify these findings.

The investigators found, importantly, the differences in bone mineral density Z-scores were independent of age, level of glucose control (HbA1c) and prepubertal stage.

The investigators concluded type 1 diabetes mellitus (T1DM) decreases bone mineral density (BMD) Z-scores in the whole body and lumbar spine in children and adolescents.

Original title:
Association between type 1 diabetes mellitus and reduced bone mineral density in children: a meta-analysis by Zhu Q, J Xu J, […], Shi J.

Link:
https://pubmed.ncbi.nlm.nih.gov/33404757/  

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Objectives:
The role of zinc in the etiology of type 2 diabetes has been widely reported in recent decades. However, much remains uncertain concerning the effect of zinc on the risk of developing type 2 diabetes. Therefore, this review article has been conducted.

Does zinc reduce risk of type 2 diabetes?

Study design:
This review article included 16 studies.
There was no publication bias.

Results and conclusions:
The investigators found in 7 prospective cohort studies and 1 cross-sectional study (146,027 participants aged between 18 and 84 years and of both genders, belonging to different ethnic groups. Of which, 11,511 type 2 diabetes cases) when comparing the highest versus lowest dietary zinc intakes, a significantly reduced risk of 13% [OR = 0.87, 95% CI = 0.78-0.98, I2 = 64.5%, p = 0.003] for type 2 diabetes.
This relationship was stronger and more evident in rural compared to urban areas [rural areas: OR = 0.59, 95% CI = 0.48-0.73, I2 = 0.0%, p = 0.843 versus urban areas: OR = 0.94, 95% CI = 0.86-1.02, I2 = 43.9%, p = 0.113].

The investigators found no association between supplementary [OR = 0.94, 95% CI = 0.75-1.19, I2 = 85.4%, p = 0.009] or total zinc intake from both diet and supplementation [OR = 0.95, 95% CI = 0.82-1.11, I2 = 56.5%, p = 0.129] and type 2 diabetes risk.

The investigators found in population-based studies that high serum/plasma zinc levels significantly increased risk of type 2 diabetes with 64% [OR = 1.64, 95% CI = 1.25-2.14, I2 > 22.5%, p = 0.275].

The investigators concluded high dietary zinc intake reduces risk of type 2 diabetes. This relationship is stronger and more evident in rural compared to urban areas. However, an elevated serum/plasma zinc concentration is associated with an increased risk of type 2 diabetes in the general population.

Link:
Zinc Intake and Status and Risk of Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis by Fernández-Cao JC, Warthon-Medina M, […], Lowe NM.

Link:
https://www.mdpi.com/2072-6643/11/5/1027/htm

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Serum/plasma zinc levels can be increased by eating products that contain a lot of zinc and/or taking zinc supplements.
 

Objectives:
Does magnesium reduce risk of type 2 diabetes?

Study design:
This review article included 35 cohort studies and 26 RCTs (1,168 participants).

Results and conclusions:
The investigators found compared to the lowest magnesium dietary intake, the highest level was associated with a 22% lower risk for type 2 diabetes.

The investigators found the risk for type 2 diabetes was reduced by 6% for each 100mg increment in daily magnesium dietary intake.

The investigators found in 26 RCTs (1,168 participants) that magnesium supplementation significantly reduced:
-the fasting plasma glucose (FPG) level [SMD = -0.32, 95% CI = -0.59 to -0.05];
-2-h oral glucose tolerance test (2-h OGTT) result [SMD = -0.30, 95% CI = -0.58 to -0.02];
-fasting insulin level [SMD = -0.17, 95% CI = -0.30 to -0.04];
-homeostatic model assessment-insulin resistance (HOMA-IR) score [SMD = -0.41, 95% CI = -0.71 to -0.11];
-triglyceride (TG) level;
-systolic blood pressure (SBP) and;
-diastolic blood pressure (DBP).

The investigators found trial sequential analysis (TSA) showed an inverse association, with most benefits of magnesium supplementation on glucose metabolism being stable.

The investigators concluded magnesium dietary intake has an inverse dose-response association with type 2 diabetes incidence and supplementation appears to be advisable in terms of glucose parameters in type 2 diabetes/high-risk individuals.

Original title:
Association of Magnesium Consumption with Type 2 Diabetes and Glucose Metabolism: a Systematic Literature Review and Pooled Study with Trial Sequential Analysis by Zhao B, Deng H, [...], Zhang W.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31758631

Additional information of El Mondo:
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Objectives:
Observational evidence suggests higher nut consumption is associated with better glycemic control. However, it is unclear if this association is causal. Therefore, this review article has been conducted.

Is there a causal relationship between consumption of tree nuts or peanuts and reduced risk of type 2 diabetes?

Study design:
This review article included a total of 40 RCTs with 2,832 unique participants, with a median duration of 3 months (range: 1-12 months).

Results and conclusions:
The investigators found overall consumption of tree nuts or peanuts had a favourable effect on HOMA-IR values [WMD = -0.23, 95% CI = -0.40 to -0.06, I2 = 51.7%] and fasting insulin levels [WMD = -0.40 μIU/mL, 95% CI = -0.73 to -0.07 μIU/mL, I2 = 49.4%].

The investigators found, however, there was no significant effect of nut consumption on fasting blood glucose levels [WMD = -0.52 mg/dL, 95% CI = -1.43 to 0.38 mg/dL, I2 = 53.4%] or HbA1c [WMD = 0.02%, 95% CI = -0.01% to 0.04%, I2 = 51.0%].

The investigators concluded consumption of peanuts or tree nuts decreases HOMA-IR and fasting insulin levels. These findings suggest that nut consumption may improve insulin sensitivity. In the future, well-designed clinical trials are required to elucidate the mechanisms that account for these observed effects.

Original title:
The effect of nuts on markers of glycemic control: a systematic review and meta-analysis of randomized controlled trials by Tindall AM, Johnston EA, […], Petersen KS.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30722007

Additional information of El Mondo:
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Objectives:
The incidence of type 2 diabetes mellitus (DM) has increased in the US over the last several years. The consumption of low-fat dairy foods has been linked with decreasing the risk of diabetes mellitus but studies have yet to show a clear correlation. Therefore, this review article has been conducted.

Is there a causal relationship between consumption of low-fat dairy foods and reduced risk of type 2 diabetes?

Study design:
This review article included 30 RCTs.
The total sample size was 2,900 with >50% female participants, but the distribution varied greatly across different studies.
The mean age of subjects ranged from 18-63 years.
The funnel plots for all 3 outcomes (HOMA-IR, waist circumference and body weight) did not suggest significant publication bias.

Results and conclusions:
The investigators found (794 individuals) comparing high intake to the control group, consumption of low-fat dairy foods significantly reduced the HOMA-IR values [MD = -1.21, 95% CI = -1.74 to -0.67, p 0.00001, I2 = 92%].

The investigators found (1,348 individuals) comparing high intake to the control group, consumption of low-fat dairy foods significantly reduced waist circumference [MD = -1.09 cm, 95% CI = -1.68 to -0.58, p 0.00001, I2 = 94%].

The investigators found for body weight (2,362 individuals), the low-fat dairy foods intervention group weighed 0.42 kg less than the control group [p 0.00001, I2 = 92%].

The investigators found limiting to studies that were assessed to have low risk of bias did not significantly change the point estimates or heterogeneity statistics (Q or I2) for all 3 outcomes.
Similarly excluding studies with a physical activity component did not significantly alter point estimates or heterogeneity statistics for all 3 outcomes.

The investigators concluded low-fat dairy products have a beneficial effect on HOMA-IR, waist circumference and body weight. This could impact dietary recommendations to reduce type 2 diabetes risk.

Original title:
The Effects of Dairy Intake on Insulin Resistance: A Systematic Review and Meta-Analysis of Randomized Clinical Trials by Sochol KM, Johns TS, […], Melamed ML.

Link:
https://www.mdpi.com/2072-6643/11/9/2237/htm

Additional information of El Mondo:
Find more information/studies on diabetes and dairy products intake right here.

Objectives:
In recent years, cardiovascular diseases (CVDs) have become a focus topic and global concern. There have been mixed reports on the relationship between whole grain or cereal fiber intake and the risk of type 2 diabetes. Therefore, this review article has been conducted.

Does grain or cereal fiber dietary intake reduce risk of type 2 diabetes?

Study design:
This review article included 7 cohort studies and 1 case-control study with a total of 434,903 participants and 14,728 cases of type 2 diabetes.
The average follow-up was 12.6 years.
There was no publication bias.

Results and conclusions:
The investigators found whole grain or cereal fiber dietary intake was associated with a reduced risk of 26% [combined RR = 0.74, 95% CI = 0.67 to 0.82, I2 = 56.8%, p = 0.06] for type 2 diabetes.
This reduced risk was 38% [pooled RR = 0.68, 95% CI = 0.64-0.73, I2 = 0.0%, p = 0.452] in sensitivity analysis.

The investigators found whole grain or cereal fiber dietary intake was associated with a reduced risk of 32% [combined RR = 0.68, 95% CI = 0.49 to 0.88] for type 2 diabetes among males.

The investigators found whole grain or cereal fiber dietary intake was associated with a reduced risk of 26% [combined RR = 0.74, 95% CI = 0.64 to 0.77] for type 2 diabetes among females.

The investigators concluded that increased whole grain and cereal fiber dietary intake reduce risk of type 2 diabetes.

Original title:
Whole grain and cereal fiber intake and the risk of type 2 diabetes: a meta-analysis by Wang Y, Duan Y, […], Jin Y.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6627783/

Additional information of El Mondo:
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Objectives:
Although many studies have shown that low zinc status is associated with diabetes, the putative effects of zinc supplementation on glycemic control are inconclusive. Therefore, this review article (meta-analysis) has been conducted.

Does zinc supplementation reduce risk of diabetes mellitus?

Study design:
This review article included 32 RCTs, involving a total of 1,700 participants in 14 countries.

Results and conclusions:
The investigators found overall, compared with their respective control groups, the subjects in the zinc supplementation group had a statistically significant reduction in concentrations of :
-fasting glucose [WMD = -14.15 mg/dL, 95% CI = -17.36 to -10.93 mg/dL];
-2-h postprandial glucose [WMD = -36.85 mg/dL, 95% CI = -62.05 to -11.65 mg/dL];
-fasting insulin [WMD = -1.82 mU/L, 95% CI = -3.10 to -0.54 mU/L];
-homeostasis model assessment for insulin resistance [WMD = -0.73, 95% CI = -1.22 to -0.24]:
-glycated hemoglobin [WMD = -0.55%, 95% CI = -0.84 to -0.27%] and;
-high-sensitivity C-reactive protein [WMD = -1.31 mg/L, 95% CI = -2.05 to -0.56 mg/L].

The investigators found, moreover, subgroup analyses revealed that the effects of zinc supplementation on fasting glucose were significantly influenced by diabetic status and the formulation of the zinc supplement.

The investigators concluded several key glycemic indicators are significantly reduced by zinc supplementation, particularly the fasting glucose in subjects with diabetes and in subjects who received an inorganic zinc supplement. Together, these findings support the notion that zinc supplementation may have clinical potential as an adjunct therapy for preventing or managing diabetes.

Original title:
Zinc supplementation improves glycemic control for diabetes prevention and management: a systematic review and meta-analysis of randomized controlled trials by Wang X, Wu W, [...], Wang F.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31161192

Additional information of El Mondo:
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Objectives:
Dietary proteins, including those obtained from animal and plant sources, have inconsistently been correlated with type 2 diabetes mellitus (T2DM) risk. Therefore, this review article (meta-analysis) has been conducted.

Does dietary protein intake increase risk of type 2 diabetes mellitus?

Study design:
This review article included 21 cohort studies with a total of 487,956 individuals and 38,350 T2DM cases (persons with type 2 diabetes mellitus).

Results and conclusions:
The investigators found high total dietary protein intake was associated with an increased risk of 10% for type 2 diabetes mellitus [RR = 1.10, p = 0.006] whereas moderate total dietary protein intake was not significantly associated with type 2 diabetes mellitus risk [RR = 1.00,  p = 0.917].  
Not significantly because the calculated p-value of 0.917 was larger than the p-value of 0.05.

The investigators found, moreover, an increased risk of 13% [RR = 1.13, p = 0.013] for type 2 diabetes mellitus was observed with high  dietary animal protein intake whereas moderate animal protein intake had little or no effect on type 2 diabetes mellitus risk [RR = 1.06, p = 0.058].

The investigators found, high dietary intake of plant protein did not affect type 2 diabetes mellitus risk [RR = 0.93, p = 0.074], whereas moderate intake was associated with a reduced risk of 6% for type 2 diabetes mellitus [RR = 0.94, p  0.001].

The investigators concluded high dietary total protein and dietary animal protein intakes are associated with an increased risk of type 2 diabetes mellitus, whereas moderate plant protein intake is associated with a decreased risk of type 2 diabetes mellitus.

Original title:
Dietary protein intake and subsequent risk of type 2 diabetes: a dose-response meta-analysis of prospective cohort studies by Ye J, Yu Q, [...], Wang Y.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30929078

Additional information of El Mondo:
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A diet with high protein intake is a diet with a minimum of 35 En% protein (En% = energy percentage). These products from the supermarket contain at least 35 En% protein.
35 En% protein means that the amounts of protein contribute 35% to the total calories (kcal) of the diet.
If the diet contains 2000 kcal, 175 grams of protein contribute 35% to this 2000 kcal.
1 gram of protein gives 4 kcal. Thus, 175 grams of protein provide 700 kcal and 700 kcal is 35% of 2000 kcal.

A diet with moderate protein consumption is a diet with 20-25 En% protein. The easiest way to follow a diet with moderate protein consumption is to choose only products/meals that also contain 20-25 En% protein. These products from the supermarket contain 20-25 En% protein.

 

Objectives:
The role of gut microbiota in the management of diabetes has been shown. Several current trials are investigating the effect of probiotics and prebiotics, which are widely used to modulate intestinal microbiota, on inflammatory factors and biomarkers of oxidative stress in diabetic patient. However, their findings are controversial. Therefore, this review article (meta-analysis) has been conducted.

Do probiotic and synbiotic supplementation improve biomarkers of inflammation and oxidative stress in diabetic patients?

Study design:
This review article included 16 RCTs (n = 1,060).

Randomized controlled trials (RCTs) reported the effect of probiotics or synbiotics on circulating (serum and plasma) inflammatory marker (hs-CRP) and oxidative stress indicators (malondialdehyde [MDA], glutathione [GSH], nitric oxide [NO] and total antioxidant capacity [TAC]) among patients with diabetes.

The methodological quality varied across these trials.

Results and conclusions:
The investigators found probiotic and synbiotic supplementation significantly decreased hs-CRP level [SMD = -0.38, 95% CI = -0.51 to -0.24, p = 0.000] and the oxidative stress indicator malondialdehyde [SMD = -0.61, 95% CI = -0.89 to -0.32, p = 0.000] in diabetic patients compared to those in subjects receiving placebos.

The investigators found, in addition, probiotic and synbiotic supplementation significantly increased total antioxidant capacity [SMD = 0.31, 95% CI = 0.09 to 0.52, p = 0.006], nitric oxide [SMD = 0.62, 95% CI = 0.25 to 0.99, p = 0.001] and glutathione [SMD = 0.41, 95% CI = 0.26, 0.55, p = 0.000] levels.

The investigators concluded that probiotic and synbiotic supplementation improve biomarkers of inflammation and oxidative stress in diabetic patients. Further studies are needed to develop clinical practice guidelines for the management of inflammation and oxidative stress in these patients.

Original title:
The effect of probiotic and synbiotic supplementation on biomarkers of inflammation and oxidative stress in diabetic patients: A systematic review and meta-analysis of randomized controlled trials by Zheng HJ, Guo J, [...], Wang Y.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30794924

Additional information of El Mondo:
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Oxidative stress is an imbalance between free radicals and antioxidants in your body. Antioxidants can reduce oxidative stress.
 

Objectives:
Various mechanisms link higher total homocysteine to higher insulin resistance and risk of type 2 diabetes (T2D). Folate supplementation is recognized as a way to lower homocysteine. However, randomized controlled trials (RCTs) show inconsistent results on insulin resistance and type 2 diabetes outcomes. Therefore, this review article (meta-analysis) has been conducted.

Does folate supplementation improve insulin resistance and type 2 diabetes outcomes?

Study design:
This review article included 29 RCTs (22,250 participants) that assessed the effect of placebo-controlled folate supplementation alone or in combination with other B vitamins on fasting glucose, insulin, homeostasis model assessment for insulin resistance (HOMA-IR), glycated hemoglobin (HbA1c) or risk of type 2 diabetes.

The meta-analysis was conducted using both random- and fixed-effects models to calculate weighted mean differences (WMDs) or risk ratios with 95% CIs.
Heterogeneity was low in all meta-analyses.

Results and conclusions:
The investigators found when compared with placebo, folate supplementation significantly lowered fasting insulin [WMD = -13.47 pmol/L, 95% CI = -21.41 to -5.53 pmol/L, p 0.001] and HOMA-IR [WMD = -0.57 units, 95% CI = -0.76 to -0.37 units, p 0.0001], but no overall effects were observed for fasting glucose or HbA1c.

The investigators found subgroup analysis showed no signs of effect modification except for change in homocysteine, with the most pronounced effects in trials with a change of >2.5 µmol/L.
Changes in homocysteine after folate supplementation correlated with changes in fasting glucose [β = 0.07, 95% CI = 0.01 to 0.14, p = 0.025] and HbA1c [β = 0.46, 95% CI = 0.06 to 0.85, p = 0.02].

The investigators found only 2 studies examined folate supplementation on risk of type 2 diabetes and they found no change in RR [pooled RR = 0.91, 95% CI = 0.80 to 1.04, p = 0.16].

The investigators concluded that folate supplementation lowers fasting insulin and HOMA-IR. However, folate supplementation does not reduce risk of type 2 diabetes.

Original title:
Effect of folate supplementation on insulin sensitivity and type 2 diabetes: a meta-analysis of randomized controlled trials by Lind MV, Lauritzen L, [...], Eriksen JN.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30615110

Additional information of El Mondo:
Find more information/studies on diabetes and folate (also called folic acid) right here.
 

Objectives:
Evidence from randomized controlled trials (RCTs) suggests that viscous dietary fiber may offer beneficial effects on glycemic control and, thus, an improved cardiovascular disease risk profile. Therefore, this review article (meta-analysis) has been conducted.

Does viscous dietary fiber supplementation improve glycemic control in type 2 diabetes?

Study design:
This review article included 28 RCTs of ≥3 weeks in duration that assessed the effects of viscous fiber on markers of glycemic control in type 2 diabetes with a total of 1,394 participants.

Results and conclusions:
The investigators found that viscous fiber at a median dose of ∼13.1 g/day significantly reduced HbA1c in type 2 diabetes [MD = -0.58%, 95% CI = -0.88 to -0.28, p = 0.0002] compared with control and in addition to standard of care.

The investigators found that viscous fiber at a median dose of ∼13.1 g/day significantly reduced fasting blood glucose in type 2 diabetes [MD = -0.82 mmol/L, 95% CI = -1.32 to -0.31, p = 0.001] compared with control and in addition to standard of care. 

The investigators found that viscous fiber at a median dose of ∼13.1 g/day significantly reduced HOMA-insulin resistance in type 2 diabetes [MD = -1.89, 95% CI = -3.45 to -0.33, p = 0.02] compared with control and in addition to standard of care.

The investigators found the certainty of evidence was graded moderate for HbA1c, fasting glucose, fasting insulin and HOMA-IR and low for fructosamine.

The investigators concluded that 13.1 g/day viscous fiber supplements improve conventional markers of glycemic control beyond usual care and should be considered in the management of type 2 diabetes.

Original title:
Should Viscous Fiber Supplements Be Considered in Diabetes Control? Results From a Systematic Review and Meta-analysis of Randomized Controlled Trials by Jovanovski E, Khayyat R, […], Vuksan V.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30617143

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