Evalution of Body Mass Index (BMI) Percentile cut-off Levels with Reference to Insulin Resistance: A Comparative Study on South Indian Obese and Non-Obese Adolescents

Objectives: To investigate the relationship of Body Mass Index (BMI) percentile cut off with Homeostasis Model Assessment-Insulin Resistance (HOMA-IR), a surrogate marker for insulin resistance in obese, overweight and non-obese adolescents. Study Design: A cross-sectional analysis of 120 adolescents (divided into sixty overweight/obese and an equal number of non-obese) was performed on nondiabetic, nonpregnant (11 to 18 year old school going) adolescents in south Indian (Puducherry) population. The main outcome measure of insulin resistance was calculated as HOMA-IR (greater than 3.16). Obesity was defined as per the BMI criteria, BMI greater than or equal to 95(th) percentile, overweight greater than or equal to 85(th) percentile and non-obese less than 84.9(th) percentile. All adolescents were subjected to analysis of anthropometric parameters that included weight, height and BMI (body mass index). Biochemical parameters, namely venous plasma glucose (fasting) and venous plasma insulin (fasting) were included for insulin resistance calculation by HOMA-IR. Results: Having a BMI of greater than or equal to 85th percentile-was associated with high HOMA-IR levels. As the BMI percentile increased, HOMA-IR levels also increased. Prevalence of insulin resistance for a BMI percentile of less than 84.9 was nil. Prevalence of insulin resistance for a BMI percentile of 85-94.9 was 26%. Prevalence of insulin resistance for BMI of greater than or equal to 95th percentile was 64%. Conclusion: Insulin resistance is highly prevalent in obese and overweight adolescents as compared to that in non-obese adolescents. The onset of Impaired Fasting Glucose (IFG) is associated with the development of severe hyper-insulinaemia in obese adolescents and early primordial and primary prevention can thus alleviate the burden of future cardiometabolic disorders.