Evaluation of surrogate markers for insulin resistance for defining metabolic syndrome in urban Indian adolescents.

OBJECTIVE To compare parameters of insulin resistance, with special reference to McAuley index, in urban Indian adolescents, and to establish their cut-off values for defining metabolic syndrome. DESIGN Cross-sectional study. SETTING Schools located in four different geographical zones of Delhi, India. PARTICIPANTS 695 apparently healthy adolescents grouped as normal weight (298), overweight (205) and obese (192). OUTCOME MEASURES Cut-off point for indices of insulin resistance was assessed by fasting insulin, insulin glucose ratio, and other methods (HOMA model, QUICKI, McAuley index) to define metabolic syndrome. RESULTS The McAuley index increased progressively from normal weight to obese adolescents in both sexes. McAuley index was significantly lower in adolescents with metabolic syndrome (5.36 ± 1.28 vs. 7.05 ± 1.88; P<0.001). McAuley index had the highest area under curve of receiver operator characteristics [0.82 (0.02)] as compared to other indices of insulin resistance. McAuley index of 6.23 had the highest specificity (88%) with sensitivity of 63.3% for diagnosing metabolic syndrome, whereas insulin glucose ratio had the highest sensitivity (79.7%) but low (55.5%) specificity. McAuley index was negatively correlated with height (r= -0.257, P=<0.001), weight (r= -0.537, P=<0.001), body mass index (r= -0.579, P<0.001), waist circumference (r= -0.542, p<0.001), and waist hip ratio (r= -0.268, P<0.001). CONCLUSIONS Among various parameters of insulin resistance, McAuley index had the highest specificity, and insulin glucose ratio had the highest sensitivity in diagnosing metabolic syndrome in urban Indian adolescents.