Effect of a fermented dietary supplement containing chromium and zinc on metabolic control in patients with type 2 diabetes: A randomized, placebo-controlled, double-blind cross-over study

Background: For the increasing development of type 2 diabetes dietary habits play an important role. In this regard, dietary supplements are of growing interest to influence the progression of this disease. Objective: The aim of this study was to investigate the effect of a cascade-fermented dietary supplement based on fruits, nuts, and vegetables fortified with chromium and zinc on metabolic control in patients with type 2 diabetes mellitus. Methods: This was a randomized, placebo-controlled, double-blind, intervention study under free-living conditions using a cross-over design. Thirty-six patients with type 2 diabetes mellitus were enrolled and randomized either to receive a cascade-fermented dietary supplement enriched with chromium (100 μg/d) and zinc (15 mg/d) or a placebo similar in taste but without supplements, over a period of 12 weeks. After a washout period of 12 weeks, the patients received the other test product. The main outcome variable was the levels of glycated hemoglobin (HbA_1c ). Other outcome variables were fasting blood glucose, fructosamine, and lipid parameters. Results: Thirty-one patients completed the study. HbA_1c showed no relevant changes during both treatment periods, nor was there a relevant difference between the two treatments (HbA1c : p=0.48). The same results were found for fructosamine and fasting glucose (fructosamine: p=0.9; fasting glucose: p=0.31). In addition, there was no effect on lipid metabolism. Conclusion: This intervention study does not provide evidence that a cascade-fermented plant-based dietary supplement enriched with a combination of chromium and zinc improves glucose metabolism in patients with type 2 diabetes mellitus under free-living conditions.