Zinc Supplementation Does Not Affect Glucagon Response to Intravenous Glucose and Insulin Infusion in Patients with Well-Controlled Type 2 Diabetes.

Glucagon dysregulation is an essential component in the pathophysiology of type 2 diabetes. Studies in vitro and in animal models have shown that zinc co-secreted with insulin suppresses glucagon secretion. Zinc supplementation improves blood glucose control in patients with type 2 diabetes, although there is little information about how zinc supplementation may affect glucagon secretion. The objective of this study was to evaluate the effect of 1-year zinc supplementation on fasting plasma glucagon concentration and in response to intravenous glucose and insulin infusion in patients with type 2 diabetes. A cross-sectional study was performed after 1-year of intervention with 30 mg/day zinc supplementation or a placebo on 28 patients with type 2 diabetes. Demographic, anthropometric, and biochemical parameters were determined. Fasting plasma glucagon and in response to intravenous glucose and insulin infusion were evaluated. Patients of both placebo and supplemented groups presented a well control of diabetes, with mean values of fasting blood glucose and glycated hemoglobin within the therapeutic goals established by ADA. No significant differences were observed in plasma glucagon concentration, glucagon/glucose ratio or glucagon/insulin ratio fasting, after glucose or after insulin infusions between placebo and supplemented groups. No significant effects of glucose or insulin infusions were observed on plasma glucagon concentration. One-year zinc supplementation did not affect fasting plasma glucagon nor response to intravenous glucose or insulin infusion in well-controlled type 2 diabetes patients with an adequate zinc status.