Umbilical waist-to-height ratio and trunk fat mass index (DXA) as markers of central adiposity and insulin resistance in Argentinean children with a family history of metabolic syndrome.

Central adiposity is increasing in childhood. To find a simple index of central fatness that accurately predicts insulin resistance we studied 55 obese children and 53 siblings, aged 6-16 years. We recorded the family metabolic score, calculated clinical and DXA-derived fat distribution indexes and HOMA-IR. Umbilical waist-to-height ratio (W-to-Ht) had the best combination of ROC area (0.99, IC95: 0.93 to 1.0), Youden's index (0.976), coefficient of variation (4.9) and correlation with HOMA-IR (r = 0.58, p < 0.0001); it also correlated (p < 0.001) with BMI (r = 0.95) and DXA-trunk fat mass index (r = 0.93). It was the best predictor of insulin resistance in a multiple regression model (p < 0.0001). Odds ratios for insulin resistance were 9.33 when the family score was >10 (p < 0.01) and 14.35 when umbilical W-to-Ht was >0.54 (p < 0.0001). Umbilical W-to-Ht, a simple marker of central adiposity, strongly relates to children's DXA-trunk fat mass index and insulin resistance.