Influence of Serum Levels of Vitamin D on Insulin Resistance in Patients with Type II Diabetes Mellitus

Abstract

Background: Vitamin D plays an important role in bone and modulates mineral metabolism and immune function with probable link to several chronic and infectious conditions. In vivo studies have revealed that vitamin D deficiency reduces insulin secretion capacity of the islet beta cells in pancreas. Several studies have shown a correlation between vitamin D levels and insulin resistance, nonetheless, extensive studies showing the relationship between the two are lacking especially among southern Indian population. So the present study was aimed at evaluating the relationship between vitamin D and insulin resistance by using homeostatic model assessment-insulin resistance (HOMA-IR). Materials and methods: In a cross-sectional study, 184 people among which 92 were diabetic and 92 were nondiabetic were recruited at RL Jalappa Hospital, Kolar in the Department of Medicine between May 2018 and April 2019. Fasting serum insulin (I0), fasting plasma glucose (G0), hemoglobin A1c (HbA1C), renal function test, liver function test (LFT), lipid profile, and vitamin D levels were estimated. IBM SPSS version 22 was used for statistical analysis. Results: The prevalence of vitamin D deficiency in our study was (72) 78.2% among diabetic cases and (59) 64.1% among the nondiabetic controls, with the diabetic cases showing lower levels of vitamin D than the controls, however, it was not statistically significant. There was no significant difference in homeostatic model assessment-beta-cell function (HOMA-B) and HOMA-IR between vitamin D deficient and nondeficient groups among cases and controls. Conclusion: Vitamin D deficiency is prevalent in both type II diabetes mellitus (T2DM) as well as nondiabetic. Furthermore, there is no association between vitamin D deficiency and insulin resistance or beta-cell function.