Correlation between body mass index and waist circumference associated with insulin resistance in Eastern Cape Province of South Africa: Implications for anti-diabetes campaign

Background: Body mass index (BMI) is commonly used in typical rural community health centers where the majority of people live in impoverished rural South Africa. We evaluated the correlation between BMI and Waist circumference (WC) with a view to recommend substituting BMI with WC as measure of insulin resistance in rural communities. Design and Methods: A total of 385 nondiabetic adult subjects attending community health centers in Eastern Province, South Africa, who had not eaten any break fast participated in the study. Anthropometric measures were done under trained supervision. Blood samples were collected for estimation of fasting insulin and fasting blood glucose levels. Two validated surrogate measures of insulin resistance were used: Homeostasis model assessment of insulin resistance (HOMA-IR) and Quantitative Insulin sensitivity Check Index (QUICKI. Results: Over 45% of the people surveyed were obese with over 10% being morbidly obese. The aim was to determine whether waist circumference alone can be used as the simplest, cheapest and reliable predictor of insulin resistance and obesity. Waist circumference was found to be significantly correlated with BMI: R = 0.775, P =0.00, for women and R =0.847, P = 0.00 for men and r =0.872, P=0.001 using HOMA-IR and QUICKI (r = 0.866, P =0.01) as the surrogate indices of insulin resistance. Conclusions: Waist circumference is significantly correlated with BMI according to surrogate indices of insulin resistance. It is recommended that waist circumference should replace BMI as indicator of insulin resistance, because measuring waist circumference is very simple and affordable instrument.