Determining the waist circumference that predicts pre-diabetes (insulin resistance) in Eastern Cape Province of South Africa

Abstract

Background. In South Africa, type 2 diabetes (T2DM) accounts for 58 deaths per day and is the fifth highest cause of death largely because of the overweight and obesity tsunami that can easily be prevented. Almost 74% of the subjects were either overweight or obese with, over 10% being morbidly obese. On the basis of the close association of abdominal obesity with both waist circumference and insulin resistance, the purpose of this study was to determine the optimal waist circumference that predicts insulin resistance/pre-diabetes) in Eastern Cape Province of South Africa for use in monitoring overweight/obesity in rural and economically disadvantaged communities. Design and methods. Four hundred and fifty one (451) nondiabetic adult subjects attending community health centers in Eastern Cape Province, who had not eaten any breakfast participated in the study. Anthropometric measures were performed under trained supervision. Blood samples were collected for estimation of fasting insulin and fasting blood glucose levels. The following surrogate measures of insulin resistance were used: Homeostasis model assessment of insulin resistance (HOMA-IR) and Quantitative Insulin sensitivity Check Index (QUICKI).  Results. The optimal waist circumference cutoff that predicts insulin resistance was ≥ 90 cm for men and ≥ 100 cm for women. The IDF cutoffs are ≥ 94 cm for men and ≥ 80cm for women. The study was a convenience sample consisting of individuals seeking medical attention at a health center. Thus, findings may not be representative of the Eastern Cape Province population. (Perhaps, a stratified random sample of the Province is needed).  The limitations, notwithstanding, the significance of the study lies in the fact that we have identified a simple and affordable method (optimal cutoff waist circumference) that Eastern Cape residents can use to monitor and control the propensity to gain weight, and take the necessary steps to forestall the concomitant on set of type 2 diabetes by reducing insulin resistance.