Effect of Zinc Supplements on Glycaemic Control in Adults with Pre-Diabetes and Type Two Diabetes Mellitus - A Systematic Review

Diabetes prevalence is increasing exponentially world-wide. Pre-diabetes, which is borderline diabetes, is also on the rise. New remedies are continually being sought to improve glycaemic control. Zinc shares a multivalent relationship with insulin and glucose metabolism. Zinc is also found to be deficient amongst people with diabetes as compared to healthy individuals. It effects insulin synthesis, storage and action, and has been suggested as a potential therapeutic agent for hyperglycaemia. This review addresses the question: “Are zinc supplements effective in reducing blood glucose levels in adults with diabetes and pre-diabetes?”

6 electronic databases were searched and several trial registers were screened for ongoing studies. Some of the search terms used were “diabetes”, “pre-diabetes”, “blood glucose”, “zinc”, “HbA1c” etc. Search was carried out using Boolean Operators. Retrieved studies were screened and study selection was carried out as per PRISMA chart. Randomised and non-randomised clinical trials involving adults with pre-diabetes and type 2 diabetes, where zinc supplementation was used as an intervention were included. Systematic and consistent data-extraction was done using a standard data-extraction table. Included studies were critically appraised for their quality using the Risk of Bias tool by Cochrane Collaboration for systematic reviews. This study is a narrative synthesis, and not a meta-analysis.