Characterization of alterations in carbohydrate metabolism in children with Prader-Willi syndrome.

Objective: To study carbohydrate metabolism and insulin sensitivity and secretion in children and adolescents with Prader-Willi syndrome (PWS) compared with multifactorial obesity (MO) controls.

Patients And Methods: Seventy-five patients with PWS and 395 controls with MO were studied by oral glucose tolerance test. Insulin resistance (IR) and beta-cell function were assessed by homeostasis model assessment (HOMA), insulin glucose index, fasting insulin and insulin sensitivity index.

Results: The incidence of diabetes mellitus was 0% in PWS and 1.5% in MO, while carbohydrate intolerance was 9.3% in the former group and 7.6% in the latter (NS); basal insulin level (12 +/- 8.2 vs 22.3 +/- 25 mU/ml) and HOMA-IR (2.47 +/- 1.6 vs 4.18 +/- 5.05) were lower in PWS (p = 0.004 and 0.04, respectively), whereas HOMA beta-cell index was lower in PWS than in MO (59 +/- 42 vs 102 +/- 119, p = 0.03). ISI Composite was higher in PWS compared to MO (6 +/- 5.7 vs 4.18 +/- 5.05, p = 0.04).

Conclusion: Patients with PWS presented lower insulin resistance and a dissociation between beta-cell secretion and the degree of obesity.