Zinc's role in the glycemic control of patients with type 2 diabetes: a systematic review

Past research has shown the importance of zinc in several metabolic processes, such as the glucidic metabolism. The present systematic review aims to discuss zinc's participation in the glycemic control of type 2 diabetes mellitus (DM2) patients. In order to accomplish that, a systematic search was performed in the Pubmed database using the following indexed and theme-related descriptors: "zinc" AND "type 2 diabetes mellitus", AND MeSH terms related to glycemic control combined with the boolean operator OR. In total, 1078 articles were retrieved from the research, of which 15 articles of original studies conducted with DM2 patients were included, with three being about the effect of mineral supplementation and 12 reporting observational studies. The main findings of these studies consisted of low body contents of zinc and high excretion of zinc in urine. Hyperglycemia was one of the mechanisms that caused these alterations owing to its interference in zinc reabsorption via renal cells. Another evidence was the negative correlation between the glycated hemoglobin percentage (%HbA1c) and the plasma zinc levels. Additionally, it has been observed that zinc supplementation in DM2 patients has improved glycemic control, since the %HbA1c significantly reduced in these individuals. This present review shows the positive effect of adequate zinc levels on glycemic control, whether it is through dietetic ingestion or supplementation, since its role in insulin homeostasis is clear.