Association of Vitamin D with Microvascular Complications among the Cases of Type-2 Diabetes Mellitus: A Case Control Study

Introduction: Vitamin D has a huge impact on human health and disease. It plays an important role in glucose homeostasis by promoting insulin secretion and reducing resistance. Vitamin D insufficiency may increase the occurrence and progression of type-2 Diabetes Mellitus (T2DM) and its associated complications. Objectives: The present study aims to compare vitamin D levels in type-2 diabetes mellitus patients with and without microvascular complications and also to investigate the relationship between vitamin D insufficiency and T2DM microvascular consequences. Material & Methods: A case control study was conducted on 60 type-2 diabetes mellitus patients, aged between 40-70 years, as per inclusion and exclusion criteria and divided into 2 groups. Group-I: T2DM patients with microvascular complications (n=30) served as study group; and Group II: T2DM patients without microvascular complications (n=30) used as control group. Venous blood samples were collected using aseptic techniques. Fasting blood sugar, glycosylated haemoglobin (HbA1c), post prandial blood sugar and vitamin D levels were measured. The collected data were analyzed using student “t” test for evaluating the differences between both groups in reference to above parameters. Pearson correlation analysis was used to find out association of vitamin D levels with glycaemic control (blood sugar and HbA1C levels). The results were expressed as Mean ± Standard Deviation (SD). Results: Vitamin D deficiency and insufficiency was found to be significantly higher in T2DM patients with microvascular complications (14.51 ± 3.79 vs 19.80 ± 5.02) as compared with T2DM patients without microvascular complications (p< 0.01). Vitamin D insufficiency was found to be more common in females than males (10.52 ± 1.59 vs 16.50 ± 2.77; p<0.001). Vitamin D level also shows statistically significant negative correlation with HbA1C (r=-0.887, p <0.001); fasting blood sugar (FBS) r=-0.901, p<0.001; and 2 hour post prandial blood sugar (PPBS) r=-0.583, p<0.001 and prevalence of microvascular complications. Conclusion: Vitamin D insufficiency is significantly associated with glycaemic control and with any of the individual microvascular complications, i.e. neuropathy, retinopathy, and nephropathy. Therefore, early screening for vitamin D levels in T2DM patients may be beneficial due to the diverse implications of vitamin D deficiency and insufficiency. Estimation and correction of vitamin D deficiency may also help in prevention of microvascular complications.