Insulinogenic index at 15 min as a marker of stable eating behavior in bulimia nervosa

Background & aims: The aim of this study was to determine the relationship between insulinogenic index at 15 min (II15 min), body weight maintenance, and the presence of vomiting in patients with bulimia nervosa. Methods: Forty-eight bulimic inpatients and 14 controls underwent an oral glucose tolerance test on the seventh hospital day. We calculated II15 min and other biological markers, including serum amylase concentrations. During the first week after admission, we monitored the frequency of vomiting and calculated changes in body weight. Patients were divided into 4 subgroups according to the presence of vomiting and weight loss. Results: Two-factor analysis of variance of the II15 min value revealed significant main effects of vomiting and body weight change (P<0.001 for both). The II15 min values for controls and bulimic patients with weight loss and no vomiting were lower than those of other bulimic groups. The II15 min values were positively correlated with serum amylase concentrations (r=0.37, P<0.01), body weight change (r=0.35, P<0.05), and frequencies of vomiting (r=0.49, P<0.05). Conclusions: These findings suggest that II15 min values may be a useful marker for assessing the stability of eating behavior in patients with bulimia nervosa.