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), HbA 1 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.