Background: Insulin resistance (IR) is a risk factor for diabetes and atherosclerotic diseases. The metabolic syndrome (MetS) reflects IR. Waist circumference (WC) is the most easily registered component of MetS. The objective was to compare WC alone with MetS as defined by the National Cholesterol Education Program (NCEP) and the International Diabetes Federation (IDF) for their abilities to predict IR in elderly without known diabetes.
Methods: The study included 223 women and 210 men comprising 70% of a random sample of 75-year-olds from a general population. IR was conventionally defined as the gender-specific upper quartile of the Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) index in individuals without known diabetes.
Results: 1) The positive association between WC and IR is stronger in women than in men. 2) WC >88 cm alone is nearly as good as MetS, using NCEP criteria, in predicting IR in women. 3) According to the ROC curve, the optimal cut-off point for WC predicting IR was between 96 and 97 cm (men) and between 88 and 89 cm (women). The relative risk of IR was 5.6 (95% CI: 3.1-11.9) for women with WC >88 cm and 1.9 (1.5-2.8) for men with WC >96 cm. 4) The NCEP criteria predicts IR significantly better than the IDF criteria.
Conclusion: WC >88 cm in women indicates a high likelihood of IR and is almost as good as MetS defined using the NCEP criteria in predicting IR. MetS defined using the NCEP criteria predicts IR better than MetS defined using the IDF criteria.