Serum 25-OH Cholecalciferol (Vitamin D) Levels among Patients with Uncontrolled Type 2 Diabetes Mellitus- A Case-control Study

Introduction: Type 2 Diabetes Mellitus (T2DM), a common metabolic disorder characterised by hyperglycaemia is caused due to an absolute or relative insulin deficiency and/or insulin resistance. Vitamin D, a steroid hormone beyond its primary role on calcium and bone metabolism, also has been shown to have multiple other effects. Vitamin D levels have been studied in relation to glucose metabolism as role in insulin secretion and insulin resistance by many studies in the past. Aim: To estimate the levels of serum 25-OH vitamin D and to correlate with glycaemic status among uncontrolled T2DM patients. Materials and Methods: A case-control study was conducted during August-September 2021 at Melmaruvathur Adhiparasakthi Institute of Medical Sciences and Research in Melmaruvthur, Tamil Nadu, India. In this study, 50 cases (uncontrolled T2DM) and 50 controls (healthy individuals), of both sexes aged between 40- 60 years were included. Blood samples were analysed for serum 25-OH cholecalciferol (Vitamin D), fasting and postprandial plasma glucose levels and statistical analysis was done by Independent sample t-test for significance testing, odds ratio for exposureoutcome association by logistic regression and Pearson coefficient for correlation using Statistical Package for the Social Sciences (SPSS) software version 18.0. Results: Serum 25-OH vitamin D levels were significantly {p<0.005 (t=-9.005)} lower in cases {31.02±7.51 ng/mL} when compared to controls {48.30±11.29 ng/mL}. Logistic regression showed none of the predictor variables studied showing significant outcome association (p<0.05) for vitamin D predeficiency while Pearson correlation showed significant negative correlation with fasting (r=-0.463) and postprandial plasma glucose (r=-0.568), respectively at 0.01 level (2-tailed). Conclusion: Serum 25-OH Vitamin D levels were significantly lower and have significant inverse association with fasting plasma glucose levels and postprandial plasma glucose levels in uncontrolled T2DM patients. This substantiates the role of vitamin D in maintaining normal plasma glucose levels in T2DM patients. It is thereby proposed that serum 25-OH vitamin D levels be measured and followed-up for better glycaemic control among T2DM patients.