GLUCOSE-UTILIZATION IN MORBIDLY OBESE SUBJECTS BEFORE AND AFTER WEIGHT-LOSS BY GASTRIC BYPASS OPERATION

OBJECTIVE: To investigate the effect of weight reduction induced by ga stric bypass operation (GBO), on the peripheral resistance to insulin in extremely obese subjects. DESIGN: A three-stage euglycemic clamp wa s applied to assess the metabolic clearance rate of glucose (g-MCR) in lean controls and in obese subjects, prior to and 6-12 months post op eration. SUBJECTS: Six obese subjects (four obese normoglycemics-ON an d two obese non-insulin dependent diabetics-OD) before and after GBO a nd six healthy, lean controls (LC) were compared. MAIN OUTCOME MEASURE S: Body mass index after GBO, metabolic clearance rate of glucose unde r increasing insulin concentrations. RESULTS: GBO resulted in a signif icant change in body mass index from a pre-operation value (mean +/- s .d.) of 45.0 +/- 8.5 to 30.4 +/- 5.9 kg m(-2) and remained significant ly greater than controls (23.3 +/- 2.3 kg m(-2)). Glucose MCR increase d from a mean baseline value of 3.0 +/- 1.6 to 6.7 +/- 3.9 ml kg(-1) m in(-1) at post GBO (P) (P < 0.02), Similar effects were obtained under the two higher insulin concentration. CONCLUSIONS: GBO resulted in a massive reduction in BMI, that still remained above normal controls. T his could explain the effect of weight reduction to decrease, but not completely reverse, peripheral resistance to insulin associated with o besity.