Effects of zinc supplementation on serum adiponectin concentration and glycemic control in patients with type 2 diabetes

Zinc and aging: a narrative review of the effects on hematopoiesis and its link with diseases

There has been a global increase in the older population in recent decades and, as age advances, complex metabolic and epigenetic changes occur in the organism, and these may trigger some health complications commonly found among this population. Additionally, several changes occur in older people that can reduce the dietary intake or the process of nutrient absorption. In this way, tissues with high nutrient requirements are more affected. Hematopoiesis is the process of formation, development, and maturation of blood cells and is a process with a high turnover. This high demand makes the integrity of the hematopoietic process susceptible to various factors that impair physiological function, such as aging and micronutrient bioavailability. Among these micronutrients, Zinc is considered an important micronutrient, playing diverse roles across various tissues and cell types. Some of the alterations in hematopoiesis that appear as a consequence of aging and due to insufficient micronutrient intake are well described in the literature; however, not much is known about how zinc deficiency contributes towards the development of diseases seen in aging. Considering the importance of zinc to act on several biological processes, this narrative review discusses several studies related to the physiological requirements, deficiency, or excess of zinc, including studies in experimental models and humans, and aimed to shed light on the relationship between zinc and the regulation of hematopoietic tissue, exploring possible links between this mineral with common disorders that appear during aging.

Zinc Supplementation in Individuals with Prediabetes and type 2 Diabetes: a GRADE-Assessed Systematic Review and Dose-Response Meta-analysis

Zinc supplementation has therapeutic effects on cardiovascular disease (CVD) risk factors, including dyslipidemia, hyperglycemia, and inflammation as the main contributors to CVD pathogenesis. Since CVD is a major cause of mortality among people with type 2 diabetes mellitus (T2DM), this study aimed to overview the potential effects of zinc supplementation on CVD risk factors in T2DM patients. To determine appropriate randomized clinical trials (RCTs) investigating the effects of zinc supplementation on CVD risk factors, electronic sources including PubMed, Web of Science, and Scopus were systematically searched until January 2023. The heterogeneity of trials was checked using the I2 statistic. According to the heterogeneity tests, random-effects models were estimated, and pooled data were defined as the weighted mean difference (WMD) with a 95% confidence interval (CI). Of the 4004 initial records, 23 studies that met inclusion criteria were analyzed in this meta-analysis. The pooled findings indicated the significant lowering effects of zinc supplementation on triglycerides (TG), total cholesterol (TC), fasting blood glucose (FBG), hemoglobin A1C (HbA1C), and C-reactive protein (CRP), while high-density cholesterol (HDL) concentrations showed an elevation after zinc supplementation. In addition to statistical significance, the effect of zinc supplementation on most of the variables was clinically significant; however, the quality of evidence in the included studies is regarded as low or very low for most variables. Our study demonstrated that zinc supplementation has beneficial effects on glycemic control markers, lipid profile, and CRP levels as a classic marker of inflammation in T2DM. Due to the high degree of heterogeneity between studies and the low rate of quality in them, further well-designed studies are necessitated to strengthen our findings.

Therapeutic potential of adiponectin in prediabetes: strategies, challenges, and future directions

Adiponectin, an adipose-derived hormone, plays a pivotal role in glucose regulation and lipid metabolism, with a decrease in circulating adiponectin levels being linked to insulin resistance and prediabetes. This review examines the therapeutic potential of adiponectin in managing prediabetes, elucidating on multiple aspects including its role in glucose and lipid metabolism, influence on insulin sensitivity, and anti-inflammatory properties. Moreover, the paper highlights the latest strategies to augment adiponectin levels, such as gene therapy, pharmacological interventions, dietary modifications, and lifestyle changes. It also addresses the challenges encountered in translating preclinical findings into clinical practice, primarily related to drug delivery, safety, and efficacy. Lastly, the review proposes future directions, underlining the need for large-scale human trials, novel adiponectin analogs, and personalized treatment strategies to harness adiponectin's full therapeutic potential in preventing the transition from prediabetes to diabetes.

Effect of Zinc Supplementation on Lipid Profile and Body Composition in Patients with Type 2 Diabetes Mellitus: A GRADE-Assessed Systematic Review and Dose-Response Meta-analysis

The aim of this systematic review and meta-analysis of randomized controlled trials (RCTs) is to investigate the overall effects of zinc supplementation on lipid profile and body composition such as body weight (BW), body mass index (BMI), triglycerides (TG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), and high-density lipoprotein-cholesterol (HDL-C) in patients with type 2 diabetes mellitus (T2DM). Scopus, Web of Science, PubMed, and Embase databases were searched from inception through October, 2023. The I2 and Cochran's Q tests were used to assess heterogeneity between studies. Nineteen RCTs (n = 1357 participants) were included in the meta-analysis. Zinc supplementation significantly reduced TG (WMD = - 17.41 mg/dL; 95% CI: - 22.60, - 12.22; P < 0.001), TC (WMD: - 19.60 mg/dL; 95% CI: - 28.46, - 10.73, P < 0.001), LDL-C (WMD = - 8.80 mg/dL; 95% CI: - 14.80, - 2.81; P = 0.004), and BMI (WMD = - 0.53 kg/m2; 95% CI: - 1.05, - 0.01; P = 0.046) but not BW (WMD: - 0.51 kg, 95 % CI: - 1.99, 0.97, P = 0.498). Moreover, zinc supplementation increased HDL-C (WMD = 4.82 mg/dL; 95% CI: 0.88, 8.76; P = 0.016) in patients with T2DM. Our results propose that zinc supplementation may be an effective strategy for improving lipid profile and body composition in patients with T2DM.

The effects of zinc supplementation on the metabolic factors in patients with non-alcoholic fatty liver disease: a randomized, double-blinded, placebo-controlled clinical trial

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is associated with metabolic factors including obesity, dyslipidemia, insulin resistance, oxidative stress, and elevated inflammatory factors. Zinc (Zn) supplementation has been investigated as a potential adjunctive therapy in managing NAFLD outcomes.

METHODS

In this randomized, double-blinded, controlled clinical trial, 50 overweight or obese participants with NAFLD were randomized into 2 groups of 25 and received either 30 mg of daily Zn or a placebo for 8 weeks. Both groups were invited to follow a balanced energy-restricted diet and physical activity recommendations.

RESULTS

Based on the between-group comparison, Zn supplementation caused a significant increase in the Zn level (P < 0.001) and a significant decrease in weight (P = 0.004), body mass index (BMI) (P = 0.002), waist circumference (P = 0.010), aspartate transaminase (AST) (P = 0.033), total cholesterol (TC) (P = 0.045), and low-density lipoprotein cholesterol (LDL-C) (P = 0.014), but it had no significant effect on alanine transaminase (ALT), fasting blood sugar (FBS), insulin, homeostasis model assessment of insulin resistance (HOMA-IR), high-density lipoprotein (HDL), triglyceride (TG), high-sensitivity C-reactive protein (hs-CRP), malondialdehyde (MDA), and total antioxidant capacity (TAC) (P > 0.05).

CONCLUSION

The results of the present study indicated that 8-week supplementation of 30 mg daily Zn may increase the Zn serum level and decline anthropometric parameters, AST, TC, and LDL-C in NAFLD patients, so further research is suggested in the future.

TRIAL REGISTRATION

The trial was retrospectively registered at IRCT.ir as IRCT20191015045113N1 (December/8/2019).

The Effect of Zinc Supplementation on Lipid Profiles in Patients with Type 2 Diabetes Mellitus: A Systematic Review and Dose-Response Meta-Analysis of Randomized Clinical Trials

Research on the effects of zinc supplementation on lipid profiles in people with type 2 diabetes mellitus (T2DM) has been inconsistent. This systematic review and meta-analysis was performed to summarize the current data on the effects of zinc supplementation on lipid profiles in patients with T2DM. Three online databases including PubMed, Scopus, and Web of Science were searched to find relevant studies published until September 2022. The exposure was zinc supplementation, and the outcomes were low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride (TG), and total cholesterol (TC). Fourteen randomized clinical trials consisting of 1067 patients were included in the statistical analysis. Significant improvement was observed in all 4 lipid profile components. Following zinc supplementation, a significant decrease was observed in TC (weighted mean difference [WMD]: -16.16; 95% confidence interval [CI]: -26.43, -5.89; P = 0.002), LDL (WMD: -6.18; 95% CI: -9.35, -3.02; P < 0.001), and TG (WMD: -13.08; 95% CI: -21.83, -4.34; P = 0.003). After analyzing 13 studies reporting HDL, a significant increase was seen (WMD: 3.76; 95% CI: 1.30, 6.22; P = 0.003). In a nonlinear dose-response analysis, a significant inverse association was observed between <12 wk zinc supplementation and TC, LDL, and TG (TC: WMD: -5, Pnonlinearity < 0.001; LDL: WMD: -5, Pnonlinearity = 0.07, TG: WMD: -16.5, Pnonlinearity = 0.006). Nonlinear dose-response analysis shows that the optimum elemental zinc dosage for the best response to the supplementation for TC, LDL, and TG are 120, 100, and 140 mg/d, respectively (TC: WMD: -5, Pnonlinearity < 0.001; LDL: WMD: -10, Pnonlinearity = 0.006, TG: WMD: -50, Pnonlinearity = 0.031). In conclusion, we found significant changes in all 4 components of the lipid profile through zinc supplementation in T2DM patients. Based on our findings, zinc supplementation may have profound favorable consequences on the lipid profile of T2DM patients, especially in the zinc-deficient group.

Lower serum zinc level is associated with higher fasting insulin in type 2 diabetes mellitus (T2DM) and relates with disturbed glucagon suppression response in male patients

AIMS

Zinc ion can play critical role in glycemic control in diabetes mellitus (DM), contributing to both insulin synthesis and secretion. In this study, we aimed to investigate the level of zinc in diabetic patients and its association with glycemic parameters, insulin, and glucagon level.

METHODS

112 individuals (59 cases of type 2DM and 53 non-diabetic controls) were included in this study. Biochemical parameters (FBG, 2hpp, HbA1C), and zinc level in the serum were measured using colorimetric assays. Insulin and glucagon were measured by ELISA method. HOMA-IR, HOMA-B, reciprocal HOMA-B, and Quicki indices were calculated using appropriate formula. For further analysis, patients were divided into two groups: high (>135.5 μg/dl) and low (<135.5 μg/dl) zinc. Glucagon suppression was considered yes if 2hpp glucagon < fasting glucagon.

RESULTS

Our results showed that serum Zn level in type 2 DM patients was lower than control (P value=0.02). Patients with lower Zn had higher fasting insulin (P value=0.006) and higher β-cell activity index (HOMA-B, p value=0.02), however fasting glucagon and parameters of hyperglycemia (FBG, 2hpp, Hba1C) were not different. Moreover, insulin sensitivity and resistance indices (Quicki, HOMA-IR,1/HOMA-IR) showed non-significantly improved status in high Zn group. We found non-significant association between glucagon suppression and Zn level in both genders (N = 39, p value = 0.07), however, it was significant in males (N = 14, p value = 0.02).

CONCLUSION

Altogether, our results indicated reduced serum Zn in type 2DM can exacerbate hyperinsulinemia and glucagon suppression (only significant in the male), highlighting its importance in type 2DM control.

Zinc supplementation and cardiovascular disease risk factors: A GRADE-assessed systematic review and dose-response meta-analysis

BACKGROUND AND OBJECTIVE

A deficit in zinc has been related to a higher probability of developing cardiovascular diseases (CVDs). The anti-inflammatory and anti-oxidative capabilities of zinc may have a wide range of therapeutic impacts on CVDs. We conducted a comprehensive systematic review and meta-analysis of the possible impacts that zinc supplementation may have on the risk factors associated with CVDs.

METHODS

To identify eligible randomized clinical trials (RCTs) evaluating the effects of zinc supplementation on CVDs risk factors, electronic databases including PubMed, Web of Science, and Scopus were systematically searched up to January 2023. The heterogeneity of trials was checked using the I² statistic. According to the heterogeneity tests, random effects models were estimated and pooled data were defined as the weighted mean difference (WMD) with a 95% confidence interval (CI).

RESULTS

Of 23165 initial records, 75 studies that met inclusion criteria were analyzed in this meta-analysis. The pooled findings indicated the significant lowering effects of zinc supplementation on triglycerides (TG), total cholesterol (TC), fasting blood glucose (FBG), Hemoglobin A1C (HbA1C), Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), C-reactive protein (CRP), interleukin-6 (IL-6), Tumor necrosis factor-α (TNF-α), nitric oxide (NO), malondialdehyde (MDA), total antioxidant capacity (TAC), and glutathione (GSH), with no noticeable effects on low-density lipoprotein (LDL), high-density lipoprotein (HDL), insulin, systolic blood pressure (SBP), diastolic blood pressure (DBP), aspartate transaminase (AST), and Alanine aminotransferase (ALT).

CONCLUSION

Overall, zinc supplementation may boost recognized coronary risk factors that contribute to the development of CVDs. Future research should be conducted to bolster our results.

Effect of zinc supplementation in the management of type 2 diabetes: A grading of recommendations assessment, development, and evaluation-assessed, dose-response meta-analysis of randomized controlled trials

The question of whether zinc supplementation may improve cardio-metabolic health in patients with type 2 diabetes mellitus (T2DM) remains controversial and require further evaluation. This study aimed to summarize the effectiveness of oral zinc supplementation in improving cardio-metabolic risk markers in people with T2DM. We searched PubMed, Scopus, and Web of Science from inception to April 2023, for randomized controlled trials (RCTs). RCTs of type 2 diabetic adults (aged ≥18 years) comparing zinc supplementation with placebo were included. We excluded studies if not randomized, involved co-supplementation, and were conducted in children or pregnant women. Glycemic indices, lipid profiles, blood pressure, anthropometric measure, c-reactive protein (CRP), creatinine, and serum zinc were extracted. Certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methods. We used a random-effect model to perform the dose-response analysis. Effect sizes were presented as mean difference (MD) and 95% confidence interval (CI). 22 studies (n = 1442 participants) were included. The certainty of the evidence was rated as moderate to high. Zinc supplementation significantly reduced glycemic indices: including two-hour postprandial glucose (2hpp) (mean difference (MD): -34.34 mg/dl; 95%CI: -51.61∼ -17.07), fast blood sugar (FBS) (MD: -23.32 mg/dl; 95% CI: -33.81∼ -12.83), and hemoglobin A1c (HbA1c) (MD: -0.47; 95% CI: -0.71∼ -0.23). Zinc had a favorable effect on lipid profiles low-density lipoprotein (LDL) (MD: -10.76 mg/dl; CI: -17.79∼-3.73), triglyceride (TG) (MD: -18.23 mg/dl; CI: -32.81∼-3.65), total cholesterol (TC) (MD: -12.74 mg/dl; CI: -21.68∼-3.80), VLDL (MD: -5.39 mg/dl; CI: -7.35∼-3.43) and high-density lipoprotein (HDL) (MD: 4.04 mg/dl; CI: 0.96 ∼ 7.12). Systolic blood pressure (SBP) (MD): -3.64 mmHg; 95% CI: -6.77∼ -0.52), weight (MD: 1.00 kg; 95% CI: 0.34∼1.66), CRP (MD: -3.37 mg/l, 95% CI: -4.05∼ -2.70), and serum zinc (MD: 15.38 µg/dl; 95% CI: 10.74∼ 20.02) changed to a statistically significant extent with zinc supplementation. There was also a linear association between additional 10 mg/d zinc treatment with FBS, HbA1c, HDL, LDL, TG, TC, and serum zinc. A non-linear dose-response gradient was seen for FBS, HDL, and SBP (p < 0.05). Egger's test showed no substantial publication bias. Our findings strongly suggest a potential beneficial effect of zinc supplementation on type 2 diabetic patients. Further high-quality research is needed to determine the optimal form, dosage, and duration of zinc supplementation for this population.

Dietary inadequacies overestimate the blood deficiencies of magnesium, zinc, and vitamins A, C, E, and D among residents of Sao Paulo

BACKGROUND & AIMS

We aimed to estimate the prevalence of the inadequate intake and status of magnesium, zinc, and vitamins A, C, E, and D and identify factors associated with micronutrient deficiency in serum/plasma among residents of São Paulo, Brazil.

METHODS

Data from 824 individuals aged ≥14 years were obtained from the 2015 ISA-Nutrition, a population-based, cross-sectional survey. Dietary and supplement intakes were assessed using two 24-h dietary recalls, and the micronutrient inadequacies were estimated using the National Cancer Institute method. Micronutrient status was measured in serum or plasma, and deficiency was established according to the lower limit of the reference values. Receiver operating characteristic curve analysis was used to identify the effect of intake on the micronutrient status in serum/plasma. Logistic regression analysis was applied to assess the association between micronutrient status and individual characteristics.

RESULTS

More than 80% of the population had an inadequate dietary intake of magnesium, vitamin E, and vitamin D. Males had a high prevalence of inadequate dietary intake of vitamin A and zinc. A high-to-moderate prevalence of inadequate vitamin C intake was observed. Vitamin D was the only nutrient with a deficient status comparable to its dietary inadequacy. The other nutrients demonstrated a lower deficiency prevalence compared to dietary inadequacy, and vitamin A demonstrated the lowest prevalence of deficiency in plasma. Generally, dietary intake showed a non-notable association with micronutrient deficiency in serum/plasma. Individuals with fasting glucose concentrations ≥100 mg/dL and those using diuretic drugs had a higher risk of serum magnesium deficiency. Those using lipid-lowering drugs and those with high plasma adiponectin concentrations had a higher risk of serum zinc deficiency. Individuals who smoked and those with hypertension showed a higher risk of plasma vitamin C deficiency. Individuals with average leptin concentrations had a higher risk of plasma vitamin E deficiency. Finally, those with sufficient leisure-time physical activity had a lower risk of serum vitamin D deficiency.

CONCLUSIONS

Residents of the urban areas of São Paulo demonstrated substantially inadequate intakes of most of the assessed micronutrients; however, micronutrient deficiency in serum/plasma was not associated with dietary inadequacy, and it usually demonstrated a lower prevalence than dietary indicators. Thus, using micronutrient intake to determine the serum/plasma profile should be done with caution. The status of the micronutrients varied according to individual characteristics, indicating the interplay of complex mechanisms underlying micronutrient balance.

Design, synthesis and bio-evaluation of indolin-2-ones as potential antidiabetic agents

Background: Diabetes mellitus is a serious global health concern, and this is expected to impact more than 300 million people by 2025. The current study focuses on identifying substituted indolin-2-one-based inhibitors for two indispensable drug targets, α-amylase and α-glucosidase. Methods: The structures of synthetic compounds were confirmed by spectroscopic techniques and evaluated for enzyme inhibition activities. Kinetic and in silico studies were also performed. Results: All compounds exhibited good-to-moderate inhibitory potential. Most importantly, compounds 1, 2, 6, 16 and 17 were identified as potent α-glucosidase inhibitors (IC₅₀ = 9.15 ± 0.12-13.74 ± 0.12 μM). Conclusion: This study identified that these synthetic compounds might serve as potential lead molecules for antidiabetic agents.

Association of Urinary Zinc Concentrations with Dyslipidemia and Its Subtypes: Baseline Data from the Chinese Multi-Ethnic Cohort (CMEC) Study

This study elucidates the association between urinary zinc concentration and the risk of developing dyslipidemia and its subtypes in China's ethnic minority residents. Based on the baseline survey data of the Chinese Multi-Ethnic Cohort (CMEC) study, 10,620 subjects were included in the study. Logistic regression analysis evaluated the relationship between urinary zinc concentration and dyslipidemia and its subtypes. After adjustment, compared with urinary zinc concentration quartile 1 (Q1), the odds ratios (ORs) and 95% confidence intervals (95% CIs) of dyslipidemia participants in the quartile 2 (Q2), quartile 3 (Q3), and quartile 4 (Q4) groups were 1.091 (0.963, 1.237), 1.151 (1.051, 1.304), and 1.393 (1.230, 1.579), respectively (P for trend < 0.001). While that of hypertriglyceridemia participants in the Q2, Q3, and Q4 groups were 1.130 (0.979, 1.306), 1.283 (1.113, 1.480), and 1.483 (1.287, 1.709), respectively (P for trend < 0.001). Lastly, the ORs and 95% CIs of hyperbetalipoproteinemia participants in the Q2, Q3, and Q4 groups were 1.166 (0.945, 1.439), 1.238 (1.007, 1.522), and 1.381 (1.126, 1.695), respectively (P for trend < 0.002). This study found that urinary zinc concentrations were not associated with hypercholesterolemia and hypoalphalipoproteinemia. The dose-response relationship was non-linear between urinary zinc concentration and dyslipidemia, hypertriglyceridemia and hyperbetalipoproteinemia (P for trend < 0.001). In the stratified analysis, urinary zinc levels were positively associated with the risk of dyslipidemia, hypertriglyceridemia, and hyperbetalipoproteinemia in male, ≥ 60 years old, Miao nationality, hypertension, diabetes, and BMI ≥ 24.0 kg/m² subgroups. Our study provides some possible evidence that elevated urinary zinc concentrations are associated with an increased risk of dyslipidemia, hypertriglyceridemia, hyperbetalipoproteinemia.

Triangulating evidence for the causal impact of single-intervention zinc supplement on glycaemic control for type 2 diabetes: systematic review and meta-analysis of randomised controlled trial and two-sample Mendelian randomisation

Although previous studies suggested the protective effect of Zn for type 2 diabetes (T2D), the unitary causal effect remains inconclusive. We investigated the causal effect of Zn as a single intervention on glycaemic control for T2D, using a systematic review of randomised controlled trials and two-sample Mendelian randomisation (MR). Four primary outcomes were identified: fasting blood glucose/fasting glucose, HbA1c, homeostatic model assessment for insulin resistance (HOMA-IR) and serum insulin/fasting insulin level. In the systematic review, four databases were searched until June 2021. Studies, in which participants had T2D and intervention did not comprise another co-supplement, were included. Results were synthesised through the random-effects meta-analysis. In the two-sample MR, we used single-nucleotide polymorphisms (SNP) from MR-base, strongly related to Zn supplements, to infer the relationship causally, but not specified T2D. In the systematic review and meta-analysis, fourteen trials were included with overall 897 participants initially. The Zn supplement led to a significant reduction in the post-trial mean of fasting blood glucose (mean difference (MD): −26·52 mg/dl, 95 % CI (−35·13, −17·91)), HbA1c (MD: −0·52 %, 95 % CI: (−0·90, −0·13)) and HOMA-IR (MD: −1·65, 95 % CI (−2·62, −0·68)), compared to the control group. In the two-sample MR, Zn supplement with two SNP reduced the fasting glucose (inverse-variance weighted coefficient: −2·04 mmol/l, 95 % CI (−3·26, −0·83)). From the two methods, Zn supplementation alone may causally improve glycaemic control among T2D patients. The findings are limited by power from the small number of studies and SNP included in the systematic review and two-sample MR analysis, respectively.

The Effects of Zinc Sulfate Supplementation on Serum Copeptin, C-Reactive Protein and Metabolic Markers in Zinc-Deficient Diabetic Patients on Hemodialysis: A Randomized, Double-Blind, Placebo-Controlled Trial

We aimed to investigate the association between zinc (Zn) supplementation and serum levels of copeptin, high-sensitive C-reactive protein (hs-CRP), glycemic control, anthropometric parameters and renal function in Zn -deficient diabetic hemodialysis patients (DHPs). This randomized, double-blind, placebo-controlled trial (RCT) was conducted on 46 DHPs with Zn-deficiency. The Zn supplement group (n = 21) received a 220-mg/day Zn sulfate capsule (containing 50 mg Zn), and the control group (n = 25) received a placebo capsule (220 mg corn starch), for 8 weeks. Fasting, predialysis blood samples were taken at baseline and after 8 weeks to assess fasting blood glucose (FBG), serum insulin, copeptin, high-sensitive C-reactive protein (hs-CRP), blood urea nitrogen (BUN), creatinine (Cr) concentrations, and homoeostatic model assessment (HOMA-IR) and quantitative insulin-sensitivity check index (QUICKI). Compared to controls, serum copeptin (P < 0.001), hs-CRP (P < 0.001), BUN (P < 0.001), Cr (P < 0.001), Zn (P < 0.001), FBG (P < 0.001) levels, BMI (P < 0.001), and body weight (P < 0.001) were significantly affected following ZnSO4 supplementation for 8 weeks. In contrast, QUICKI (P = 0.57), HOMA-IR (P = 0.60), and serum insulin (P = 0.55) were not affected following Zn supplementation in comparison with patients receiving placebo. Zn sulfate supplementation appears to have favorable effects on serum copeptin and hs-CRP, FBG, and renal function in Zn-deficient DHPs. Iranian Registry of Clinical Trials Identifier: IRCT20190806044461N1.

Melatonin Improves Levels of Zn and Cu in the Muscle of Diabetic Obese Rats

Melatonin improves metabolic alterations associated with obesity and its diabetes (diabesity). We intend to determine whether this improvement is exerted by changing Zn and/or Cu tissue levels in liver, muscle, pancreas, and brain, and in internal (perirenal, perigonadal, and omentum) and subcutaneous lumbar white adipose tissues (IWAT and SWAT, respectively). Male Zücker diabetic fatty (ZDF) rats and lean littermates (ZL) were orally supplemented either with melatonin (10 mg/kg body weight/day) or vehicle for 6 weeks. Zn and Cu concentrations were not significantly influenced by diabesity in the analyzed tissues (p > 0.05), with the exception of Zn in liver. In skeletal muscle Zn and Cu, and in perirenal WAT, only Zn levels increased significantly with melatonin supplementation in ZDF rats (p < 0.05). This cytoplasmic Zn enhancement would be probably associated with the upregulation of several Zn influx membrane transporters (Zips) and could explain the amelioration in the glycaemia and insulinaemia by upregulating the Akt and downregulating the inhibitor PTP1B, in obese and diabetic conditions. Enhanced Zn and Cu levels in muscle cells could be related to the reported antioxidant melatonin activity exerted by increasing the Zn, Cu-SOD, and extracellular Cu-SOD activity. In conclusion, melatonin, by increasing the muscle levels of Zn and Cu, joined with our previously reported findings improves glycaemia, insulinaemia, and oxidative stress in this diabesity animal model.

The effect of curcumin and zinc co-supplementation on glycemic parameters in overweight or obese prediabetic subjects: A phase 2 randomized, placebo-controlled trial with a multi-arm, parallel-group design

Management of prediabetes is a critical step to prevent type-2 diabetes. Curcumin and zinc have been studied as an antioxidant, antiinflammatory, and antidiabetic agents. In this clinical trial, 84 subjects were randomized into curcumin (500 mg), zinc (30 mg), zinc and curcumin, and placebo groups for 90 days. At the baseline and the end of the study, the outcomes (fasting plasma glucose (FPG), 2-hour postprandial glucose (2hpp), HbA₁ C, insulin, insulin sensitivity (IS), insulin resistance (IR), β-cell function (BCF), weight, body mass index (BMI), dietary intake, and physical activity (PA)) were measured. A hypocaloric diet and PA were recommended for all subjects. In total, 82 subjects completed the study. After the intervention, dietary intake, PA, weight, and BCF% did not show a significant difference among the groups. However, subjects taking only zinc and zinc and curcumin groups experienced decreased BMI compared to the placebo (p = .01 and .007, respectively). The three treated groups had improved FPG (p = .01), 2hpp (p = .003), HbA1C (p = .004), insulin (p = .001), IS% (p = .001), and IR (p < .001) compared to the placebo. Based on these results, zinc and curcumin supplementation exerted a beneficial effect on several key glycemic parameters.

The effects of zinc supplementation on metabolic profile and oxidative stress in overweight/obese patients with non-alcoholic fatty liver disease: A randomized, double-blind, placebo-controlled trial

BACKGROUND

Evidence indicates the positive effects of zinc on insulin resistance and oxidative stress in metabolic syndrome or diabetes. Non-alcoholic fatty liver disease (NAFLD) is the main hepatic manifestation of insulin resistance and metabolic syndrome. The present study is the first clinical trial that evaluated the effects of zinc supplementation on metabolic and oxidative stress status in overweight/obese patients with NAFLD undergoing calorie- restriction diet.

METHODS

Fifty six overweight/obese patients with confirmed mild to moderate NAFLD using ultrasonography were randomly allocated to receive 30 mg elemental zinc supplement (n = 29) or placebo (n = 27) along with weight loss diet for 12 weeks. Serum levels of zinc, homeostasis model of assessment-estimated insulin resistance (HOMA-IR), lipid profile, serum superoxide dismutas1 (SOD1) and malondialdhyde (MDA) levels were assessed.

RESULTS

Serum levels of insulin, SOD1, MDA and HOMA-IR were improved in the treatment group (p < 0.05). Within group comparison showed significant reduction in serum FBS, HbA_1C, TC, LDL-c and TG in the treatment group.

CONCLUSION

Zinc supplementation for three months improved insulin resistance and oxidative stress status in overweight/obese NAFLD patients with no beneficial effects on lipid profiles over weight loss diet. Registration ID in IRCT (IRCT NO: 20181005041238N1).

Mechanisms of diabetic cardiomyopathy and potential therapeutic strategies: preclinical and clinical evidence

The pathogenesis and clinical features of diabetic cardiomyopathy have been well-studied in the past decade, but effective approaches to prevent and treat this disease are limited. Diabetic cardiomyopathy occurs as a result of the dysregulated glucose and lipid metabolism associated with diabetes mellitus, which leads to increased oxidative stress and the activation of multiple inflammatory pathways that mediate cellular and extracellular injury, pathological cardiac remodelling, and diastolic and systolic dysfunction. Preclinical studies in animal models of diabetes have identified multiple intracellular pathways involved in the pathogenesis of diabetic cardiomyopathy and potential cardioprotective strategies to prevent and treat the disease, including antifibrotic agents, anti-inflammatory agents and antioxidants. Some of these interventions have been tested in clinical trials and have shown favourable initial results. In this Review, we discuss the mechanisms underlying the development of diabetic cardiomyopathy and heart failure in type 1 and type 2 diabetes mellitus, and we summarize the evidence from preclinical and clinical studies that might provide guidance for the development of targeted strategies. We also highlight some of the novel pharmacological therapeutic strategies for the treatment and prevention of diabetic cardiomyopathy.

Overview of dietary supplements on patients with type 2 diabetes

BACKGROUND AND AIMS

The primary approach for managing type 2 diabetes mellitus (T2DM) involves lifestyle modification and diet therapy along with pharmacologic interventions. Many patients are interested to identify nutritional supplements that may provide benefit in prevention and management of diabetes. However, the efficacy and safety of nutritional supplements such as chromium, n-3 polyunsaturated fatty acids (PUFAs), vitamin D, zinc and magnesium in disease treatment is a worrying and controversial matter. In this narrative review, patients and health care providers are introduced to the effects of mentioned dietary supplements that may help in choosing or not choosing these supplements in treatment of diabetes.

METHODS

This review was carried out using comprehensive and systematic literature reports on the dietary supplements in the management of diabetes. Empirical searches were conducted using Google Scholar, Science Direct and PubMed databases. Searches were also undertaken using keywords, in English, such as "chromium" OR "vitamin D" OR "omega-3 fatty acids" OR "zinc" OR "magnesium" in combination with "type 2 diabetes".

RESULTS

The available evidence is insufficient to create a definite conclusion that nutritional supplements including chromium, n-3 PUFAs, vitamin D, zinc and magnesium might be beneficial for the prevention and treatment of T2DM and therefore, the general recommendation to use these supplements in the management of diabetes cannot be justified. The results of most studies lack uniformity across multiple aspects, including different dose and formation of supplements, duration, and subjects under intervention.

CONCLUSIONS

There is a need for well-designed, high quality, large and long-term studies to strengthen the available evidence and ensure the safety and efficacy of products.