Plasma leptin levels, insulin secretion, clearance and action on glucose metabolism in anorexia nervosa

Abstract

From a metabolic point of view, anorexia nervosa may be viewed as a mirror image of obesity. We compared insulin secretion, clearance and action on glucose metabolism during an intravenous glucose tolerance test in nine women with anorexia nervosa and in nine age-matched normal-weight controls. Insulin secretion (ISR) was derived by deconvolution of plasma C-peptide levels, insulin clearance (MCR(I)) was obtained by dividing the area under the curve (AUC(0-180 min)) of ISR by the corresponding AUC of plasma insulin levels, insulin sensitivity (S(I)) and glucose effectiveness index (S(G)) were calculated by Bergman's minimal model. The anorectic women had markedly lower BMI values (13.7+/-0.6 vs 23.2+/-0.8 kg/m2, p<0.0001) and serum basal leptin levels (2.8+/-0.6 vs 8.9+/-1.8 ng/mL, p=0.005) than control women. The anorectic women exhibited clear-cut lower fasting and post-glucose plasma insulin levels but similar corresponding plasma C-peptide concentrations when compared to controls. Consequently, ISR was similar in both groups while MCR(I) was significantly increased in anorexia nervosa (MCR(I): 3320+/-881 vs 822+/-79 mL x min(-1) x m(-2), p<0.02). The index S(I) tended to be higher in anorectic women than in normal-weight subjects, but without reaching the level of statistical significance because of a high between-subject variability (20.2+/-5.7 vs 12.5+/-2.2 10(-5) x min(-1)/pmol x L(-1), NS). The index S(G) was similar in both groups (0.022+/-0.004 vs 0.018+/-0.002 min(-1), NS). In conclusion, low plasma insulin levels observed in women with anorexia nervosa result from high MCR(I) rather than from depressed insulin secretion. Insulin sensitivity is not systematically increased and glucose effectiveness is unchanged in anorectic women when compared to normal-weight controls.