POSTGASTROPLASTY RECOVERY OF IDEAL BODY-WEIGHT NORMALIZES GLUCOSE AND INSULIN METABOLISM IN OBESE WOMEN

To study the metabolic effects of normalizing body weight, a frequently sampled iv glucose tolerance test (0.3 g/kg) was performed before [body mass index(BMI), 37.7 +/- 0.5 kg/m(2)] and 14 +/- 2 months after successful gastroplasty (BMI, 23.7 +/- 0.6 kg/m(2)) in eight obese women and, for comparison, in eight age- and weight-matched nonobese control women (BMI, 23.6 +/- 0.7 kg/m(2)). Ah subjects had normal oral glucose tolerance. The insulin secretion rate (ISR) was derived by deconvolution of plasma C-peptide levels and the insulin MCR (MCR(I)) by dividing the 0-180 min area under the curve (AUG) of ISR by that of plasma insulin levels (IRI). The insulin sensitivity index (S-I) and the glucose effectiveness index (S-G) were calculated using Bergman's minimal model. Before gastroplasty, obese subjects showed higher AUC-IRI (P<0.001) and AUC-ISR (P<0.02), lower MCR(I), (P<0.005) and S-I (P<0.002), but similar S-G values, compared to nonobese controls. After gastroplasty, the AUG-IRI dramatically decreased, due to both a reduction of AUC-ISR (from 58,252 +/- 8,437 to 36,675 +/- 4,274 pmol; P<0.05) and an increase in MCR(I) (from 658 +/- 117 to 1,299 +/- 127 mL/min.m(-2); P<0.02). S-I significantly rose from 4.74 +/- 0.74 to 9.15 +/- 0.96 10(-5) min(-1)/pmol.L (P<0.01), whereas S-G remained unchanged. Ah of these parameters became similar to those in nonobese controls (respectively, 32,522 +/- 3,458, 1,180 +/- 101, and 8.48 +/- 1.25; all P = NS). In conclusion, after gastroplasty-induced normalization of body weight, postobese women recover normal insulin secretion, clearance, and action on glucose metabolism.