Gastric bypass surgery improved beta cell function to a significantly greater extent than intensive lifestyle intervention. Supra-physiological insulin secretion and proinsulin processing may indicate excessive beta cell function after gastric bypass surgery.
Eur J Endocrinol. 2010 Nov 15. [Epub ahead of print]
Beta cell function after weight loss: a clinical trial comparing gastric bypass surgery and intensive lifestyle intervention.
D Hofsø, Morbid Obesity Centre, Vestfold Hospital Trust, Tønsberg, 3103, Norway.
Objective: The effects of various weight loss strategies on pancreatic beta cell function remain unclear. We aimed to compare the effect of intensive lifestyle intervention (ILI) and Roux-en-Y gastric bypass surgery (RYGB) on beta cell function. Design: One year controlled clinical trial (ClinicalTrials.gov identifier NCT00273104). Methods: 119 morbidly obese participants without known diabetes from the MOBIL study [mean (SD) age 43.6 (10.8) years, BMI 45.5 (5.6) kg/m2, 84 women] were allocated to RYGB (n=64) or ILI (n=55). The patients underwent repeated oral glucose tolerance tests (OGTTs) and were categorised as having either normal (NGT) or abnormal glucose tolerance (AGT). Twenty nine normal weight subjects with NGT [age 42.6 (8.7) years, BMI 22.6 (1.5) kg/m2, 19 women] served as controls. OGTT-based indices of beta cell function were calculated. Results: One year weight reduction was 30 (8) % after RYGB and 9 (10) % after ILI, (P < 0.001). Disposition index (DI) increased in all treatment groups (all P < 0.05), although more in the surgery groups (both P <0.001). Stimulated proinsulin-to-insulin (PI/I) ratio decreased in both surgery groups (both P <0.001), but to a greater extent in the surgery group with AGT at baseline (P <0.001). Post surgery, patients with NGT at baseline had higher DI and lower stimulated PI/I ratio than controls (both P <0.027). Conclusions: Gastric bypass surgery improved beta cell function to a significantly greater extent than intensive lifestyle intervention. Supra-physiological insulin secretion and proinsulin processing may indicate excessive beta cell function after gastric bypass surgery.