Effect of vitamin C on blood glucose, serum lipids & serum insulin in type 2 diabetes patients

Background & objectives: Diabetes mellitus is one of the most common metabolic disorders that causes micro- and macro-vascular complications. Because of additive effects of hyperglycaemia and hyperlipidaemia for cardiovascular diseases, lipid abnormalities should be evaluated in diabetes. As vitamin C is known for its beneficial effects on serum lipids and glycated haemoglobin (HbA(1c)), we evaluated the effect of different doses of vitamin C on blood glucose, serum lipids and serum insulin in individuals with type 2 diabetes mellitus. Methods: A total of 84 patients with type 2 diabetes referred to Yazd Diabetes Research Center, Iran, were included in the study. They received randomly either 500 mg or 1000 mg daily of vitamin C for six weeks. Fasting blood sugar (FBS), triglyceride (TG), total cholesterol (TC), low and high density lipoprotein (LDL, HDL), glycated haemoglobin HbA(IC) and serum insulin were measured before and after vitamin C consumption and the results were analyzed. Results: A significant decrease in FBS, TG, LDL, HbA(1c) and serum insulin was seen in the group supplemented with 1000 mg vitamin C. The dose of 500 mg vitamin C, however, did not produce any significant change in any of the parameters studied. Interpretation & conclusions: Our results indicate that daily consumption of 1000 mg supplementary vitamin C may be beneficial in decreasing blood glucose and lipids in patients with type 2 diabetes and thus reducing the risk of complications.