Effect of zinc as an add-on to metformin therapy on glycemic control, serum insulin, and c-peptide levels and insulin resistance in type 2 diabetes mellitus patient

Type 2 diabetes mellitus (T2DM) is an insidious disorder that may progress asymptomatically, leading to secondary complications. Diabetics were found to have a significantly lower zinc level. This study aims to assess the effects of zinc supplementation for eight weeks on glycemic control, serum insulin level, serum C-peptide level, and insulin resistance. Zinc plus metformin using group had a significant decrease in fasting blood glucose level and glycated hemoglobin, as well as a significant increase in serum insulin and C-peptide levels, but no effect on insulin resistance compared to zinc-free metformin group. Comparing the two groups at the end of the study, the combined effect of zinc plus metformin was highly important versus metformin only except for C-peptide and insulin resistance. Zinc levels were significantly elevated and returned to normal in the interventional group, while in the control group, levels were rather decreased.