RESEARCH ARTICLE International Journal of Clinical Biochemistry and Research, January – March 2015;Vol.2(1):41-47 41 A STUDY OF SDLDL-C AND INSULIN RESISTANCE IN APPARENTLY HEALTHY SOUTH INDIAN OBESE YOUNG ADULTS Viyatprajna Acharya 1,* , B D Toora 2 1 Associate Professor, Dept. of Biochemistry, Kalinga Institute of Medical Sciences, KIIT, Bhubaneswar; Odisha-751024. 2 Professor and HOD, Dept. of Biochemistry, AVMC & H, Puducherry *Corresponding Author: E-mail: acharyavp32@gmail.com ABSTRACT Background: Obesity is now occurring in pandemic proportions and has earned a new name as “Globesity” for it. Unlike earlier times developing countries too are facing the challenge of obesity and the modern epidemics have a common root cause tapering to obesity. Obesity during adolescent and young adulthood usually persists to adulthood in almost 50% cases and gives rise to early onset of type 2 diabetes mellitus, cardiovascular disorders and metabolic syndrome for which insulin resistance being the common link to all. Objective: The present study was taken up to study the prevalence of insulin resistance in apparently healthy young adult obese population and study its correlation with different cardiovascular risk factors like lipid profile and sdLDL-C. Material and Methods: In a randomized control study 106 apparently healthy young adults in the age group of 21-34 years were chosen from the community out of which 45 were obese and 61were age and gender matched non-obese controls. They were divided in obese and non-obese groups based on cut-off BMI of 25Kg/m 2 . Along with physical parameters fasting plasma glucose, lipid profile and routine biochemical parameters were assayed by standard kit methods and plasma insulin was measured by sandwich ELISA method. Different lipid ratios, atherogenic index and insulin resistance were calculated. Atherogenic index was calculated and insulin resistance was measured by HOMA-IR model and QUICKI index. Small dense LDL-C (sdLDL-C) was quantified by modified Tsutomu –Hirano method. Results: In the obese group BMI, waist circumference (WC) and waist-hip ratio (WHR) elevated significantly (p=0.0001) and TG, VLDL-C and sdLDL-C as well as atherogenic index elevated significantly (p<0.001).Significant Hyperinsulinaemia (p<0.0001) was found in the obese group and 50% of obese cases had hyperinsulinaemia. Insulin resistance calculated by HOMA-IR and QUICKI index was statistically significant (p<0.0001) in obese. Linear regression analysis showed sdLDL-C (R 2 =0.08, p=0.05 at 95% C.I.), hyperinsulinaemia (R 2 =0.089, p=0.054 at 95% C.I.) and insulin resistance (R 2 =0.099, p=0.03 at 95% C.I.) significantly dependent on WC and atherogenic index was significantly dependent on TG (R 2 =0.0036, p=0.05 at 95% C.I.) rather than any other lipid factors. On ROC analysis either method of insulin resistance showed equal efficacy (AUC for HOMA-IR= 80.3% and QUICKI = 80.14%; C.I. 95%) and atherogenic index turned out to be a better predictor than sdLDL-C (AUC for Atherogenic index= 76.14% and QUICKI = 71.46%). Conclusions: For Indian subpopulation WC and WHR should also be evaluated along with BMI. Insulin resistance should be identified early and interventional measures should be taken in terms of low carbohydrate protein-rich diet, physical exercise and insulin receptor sensitizers for a short-term. sdLDL-C rises earlier than total cholesterol and hence can be accepted as CVS risk predictor. Not many studies have been done in India on young adult health which is the group that can be targeted for early prevention of the modern epidemics like DM, Metabolic syndrome, CVS disorders and cancers. Key words: Hyperinsulinaemia, insulin resistance, Small dense-low density lipoprotein, Type-2 diabetes mellitus, metabolic syndrome. INTRODUCTION The looming health crisis around the world due to excessive weight gain has earned the epidemic of obesity a new name “Globesity”. Obesity which was thought to be the problem of developed countries is now equally shared by the developing countries and both malnutrition and obesity occur within the same countries. In India too obesity has reached epidemic proportions and as other countries, childhood obesity and obesity in youth is becoming more prevalent with little gender difference. As per 2007 National Family Health Survey data Tamilnadu ranked 4 th in obesity amongst all states of India [1]. Approximately 50% of obese adolescents with a body mass index at or above the 95th percentile become obese adults [2]. There has been an escalation of