Association between zinc nutritional status and glycemic control in individuals with well-controlled type-2 diabetes

Background/objective: Interest in healthy properties of food and nutrients as co-adjuvant in type-2 diabetes therapy has increased in recent years. Zinc supplementation trials have shown improvements in glycemic control in these patients, although it seems dependent on zinc status of the individuals. The objective of this study was to evaluate the relationship between zinc nutritional status and glucose homeostasis in patients with type-2 diabetes. Subjects/methods: Eighty patients with well controlled type-2 diabetes were recruited and clinical, anthropometric and dietary evaluations were performed. One week after, insulin sensitivity and beta cell function were assessed by a modified Frequently Sampled Intravenous Glucose Tolerance Test. Zinc status was assessed by plasma zinc and the size of rapidly Exchangeable Zinc Pool (EZP); zinc intake was also determined. Glucagon concentration was evaluated in a subsample of 36 patients. Results: Patients presented a normal zinc status although zinc intake was lower than recommended. Overall, no associations were observed between zinc status and glycemic control markers. Nevertheless, positive correlations were observed between EZP and fasting insulin concentration (rho = 0.393, p = 0.021) and HOMA-IR (rho = 0.386, p = 0.024) in women, and between plasma zinc concentration and HbA1c (rho = 0.342, p = 0.020) in men. Conclusions: No significant associations were found between zinc status and glycemic control parameters in patients with well-controlled type 2 diabetes and normal zinc status, although low-degree gender-dependent associations were observed. Further research is required to assess the role of zinc status in zinc deficient patients.