Effect of vitamin D on insulin resistance and anthropometric parameters in patients with type 2 diabetes mellitus

Abstract

Background. Prevalence of type 2 diabetes mellitus (DM) is increasing worldwide. To reduce its risk and progression, preventive programs are needed. Vitamin supplementation such as vitamin D is one of the strategies. Though little information is available regarding the association between vitamin D and type 2 DM. Human and animal studies have shown a negative correlation between serum levels of vitamin D with insulin levels and a positive correlation with insulin sensitivity. The aim of the study. This study was designed to investigate the effect of vitamin D on insulin resistance and anthropometric parameters in type 2 DM. Materials and methods. This randomized clinical investigation was conducted with 52 diabetic patients in two groups; intervention group with 28,000 Inter national Unit (IU) of cholecalciferol and the control group. After recording demographic and anthro po metric factors (waist circumference, blood pressure and body mass index), fasting blood samples was taken for measurement of blood glucose, 25-hyd roxyvitamin D [25(OH)D], insulin, glycated hemoglobin (HbA1c) and estimation of Homeostasis Model Asses sment Index (HOMA) in two times; before study and after three months. Results and discussion. Two groups had similar baseline characteristics (each group = 26 subjects). Three months after vitamin D treatment, HbA1c, anthropometric factors in intervention group stayed constant, however, serum 25(OH)D was significantly increased (p = 0.007). We found a significant increase in serum 25(OH)D levels in interventional group without any significant change in level of HbA1c and anth ropometric factors. Administration of vitamin D in diabetic subjects produced positive effects on HOMA index and insulin resistance. Association between vitamin D levels and BMI or WC was not found. Conclusion. Taken our data together available information warrants exploring the possibility that vitamin D can be more efficient in reducing type 2 DM risk. Further studies with large sample sizes are needed to show the definite effect of vitamin D on control of diabetes and its risk.