Relationship between serum vitamin D and insulin resistance in normal weight and overweight or obese men.
Obesity is a common clinical disorder featuring excessive buildup of body fat. The bioavailability of vitamin D in obese subjects is lowered because of its sequestration in the superfluous fat tissue. Hypovitaminosis D itself is associated with glucose intolerance, insulin resistance, dyslipidemia and hypertension, which are also linked to obesity. Objectives: To compare and correlate serum vitamin D and insulin resistance in controls and overweight / obese males. Study Design: Cross Sectional, Comparative Study. Setting: The study was conducted in the Department of Physiology, Post – Graduate Medical Institute (PGMI) in collaboration with Lahore General Hospital and Central Park Medical College. Period: From 7th June 2018 to 10th Oct 2018. Material and Methods: Eighty male subjects (age range 35-50 years) included in this cross-sectional comparative study were divided into two groups on the basis of BMI; Group I: non-obese (control) BMI < 25 Kg/m2 (n=40) and Group II: overweight / obese males with BMI ˃25 Kg/m2 (n=40). Fasting serum vitamin D (25 hydroxy cholecalciferol; 25-OH D, serum insulin and blood glucose levels were measured. Insulin resistance (IR) was estimated from fasting serum glucose levels taken in mmol/l and the fasting serum insulin taken in µIU/ml by using Homeostasis Model Assessment-estimated Insulin Resistance (HOMA-IR index). Results: Group II had lower serum 25-OH vitamin D levels and higher HOMA-IR index than control group. Significant negative correlation was present between serum vitamin D and HOMA-IR. Conclusion: Vitamin D deficiency may promote insulin resistance in overweight or obese individuals.