Effects of zinc supplementation on superoxide dismutase activity and gene expression, and metabolic parameters in overweight type 2 diabetes patients: A randomized, double-blind, controlled trial

Abstract

Objective: Despite the current guidelines for the management of type 2 diabetes mellitus (T2DM), patients still struggle with the hyperglycemia consequences. Imbalance in zinc homeostasis, in particular, renders diabetic patients more susceptible to the damages of oxidative stress. This study aimed to evaluate the effects of zinc supplementation on the superoxide dismutase gene expression and enzyme activity in overweight individuals with T2DM. Additionally, biochemical parameters, such as fasting blood glucose (FBG), insulin, glycated hemoglobin (HbA1c), homeostasis model of assessment-insulin resistance (HOMA-IR), serum levels of zinc and lipid profile, were assessed.

Methods: In this randomized, double-blind, placebo-controlled trial, 70 overweight (BMI > 25) T2DM patients were selected based on the inclusion criteria. They were divided into two groups for supplementation of daily 50 mg zinc gluconate or placebo for 8 weeks. Blood samples were collected from all the individuals in the zinc group and controls for analysis.

Results: The results showed that, in comparison with the control group, zinc supplementation increased both gene expression and enzyme activity of SOD (p < 0.01) as well as the levels of insulin (p = 0.02) among the patients in the zinc group. Moreover, there was a meaningful reduction in the levels of FBG, HbA1c and HOMA-IR value (p < 0.001), triglycerides and total cholesterol (p < 0.05) after the zinc treatment.

Conclusions: Taken together, the current study suggests that daily supplementation with 50 mg zinc gluconate could be a useful approach for the management of overweight T2DM.

Clinical trial registration: IRCT2015083102.

Keywords: Antioxidant therapy; Overweight; Superoxide dismutase; Type 2 diabetes mellitus; Zinc supplementation.