121ASSOCIATION OF FASTING PLASMA LEPTIN LEVEL WITH OBESITY AND INSULIN RESISTANCEObesity is a major risk factor for insulin resistance, type 2 diabetes, heart disease, and many other chronic diseases. Previous studies showed distinct inconsistency in plasma leptin levels among persons with similar body mass index. We investigated the relationships of leptin with obesity, and insulin resistance index in non-obese, overweight and obese male and female adults. The aim of this study was to investigate the associations of leptin with obesity and obesity related phenotype like insulin resistance. A total of 642 subjects were included in this cross-sectional study. Hormone and glucose levels were estimated using standard protocols. The degree of insulin resistance was calculated by homeostasis model assessment of insulin resistance. The serum leptin levels showed a significantly increase with increasing quartiles of homeostasis model assessment of insulin resistance. Subjects with baseline leptin levels in the highest quartile had a significantly higher adverse risk factor profile than those in the lowest quartile, with higher body mass index, waist to hip ratio, weight, percentage body fat, fat mass, Total cholesterol, low density lipoprotein- cholesterol, very low density lipoprotein-cholesterol, Triglyceride, blood pressure, fasting insulin, and insulin resistance index. High leptin concentration increases the risk of developing insulin resistance more than normal leptin level. The study indicates that leptin is significantly associated with obesity, insulin resistance and other obesity related phenotypes. Leptin may represent as a biomarker to recognize obese at high risk for the development of insulin resistance and diabetes.neenasrivastavakgmc@gmail.comResearch342012Leptin,Obesity,Insulin resistance, Body mass index,PhenotypesBalraj MittalDepartment of Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, U.P., India.