Objective: To gain insight into the specific mechanisms by which biliopancreatic diversion (BPD) can improve insulin action.
Materials and methods: Nondiabetic severely obese patients (n=20) undergoing BPD were included. Waist-to-hip ratio and serum concentration of glucose, insulin, and leptin were determined before, at 4-day, and at 2 months after the operation. Insulin sensitivity was calculated according to the homeostatic model assessment (HOMA IR).
Results: A marked increase of insulin sensitivity was observed by the fourth day after the operation; at the second postoperative month, when body weight was still in the obese range and the food intake was substantially similar to the preoperative one, a further improvement of insulin action towards normality was found. Moreover, before BPD HOMA IR data were independently correlated both to BMI and waist-to-hip ratio values, whereas at 2 months after the operation data were in positive correlation only with the BMI.
Discussion: In obese patients, BPD seems to achieve recovery of insulin sensitivity by specific mechanisms independent of weight loss: the main causes of this sharp improvement might be both the intramyocellular fat depletion and the interruption of enteroinsular axis.