The long-term failure of RYGB surgery in improving T2DM is related to hyperinsulinism.

Background Roux-en-Y gastric bypass (RYGB) is the gold standard method for bariatric surgery and leads to substantial improvements in Type 2 Diabetes mellitus. However, many patients experience relapses in diabetes five years after undergoing this aggressive surgical procedure. We focus on beta-cell population changes and absorptive intestinal consequences after RYGB in a healthy nonobese animal model after a long survival period. Methods For our purpose, we use three groups of Wistar rats: RYGB-operated, surgical control (Sham) and fasting control. We measure alpha-, beta-cell mass; transcription (Arx, and Pdx-1) and proliferation (Ki67) factors; glucose tolerance and insulin release after oral glucose tests; histological adaptive changes in the jejunum; and intestinal glucose transporters. Results Our results showed an early increase in insulin secretion after surgery, that decrease at the end of the study. The beta-cell mass reduces twenty-four weeks after RYGB, which coincides with decrease of Pdx-1 transcription promoter factor. These was coincident with an increase in alpha-mass and a high expression of Arx in RYGB group. Conclusions The analysis of all data showed beta-cell mass transdifferentiation into alpha-cell mass in RYGB rats. Due to long-term exhaustion of the beta-cell population by hyperinsulinism derived from digestive tract adaptation to surgery.