The mechanisms responsible for the remarkable remission of type 2 diabetes after Roux-en Y gastric bypass (RYGBP) are still puzzling. To elucidate the role of the gut, we compared β-cell function assessed during an oral glucose tolerance test (OGTT) and an isoglycemic intravenous glucose clamp (iso-IVGC) in: 1) 16 severely obese patients with type 2 diabetes, up to 3 years post-RYGBP (OB-DM); 2) 11 severely obese normal glucose tolerant controls (OB-NGT); 3) 7 LEAN controls. Diabetes remission was observed after RYGBP. β-cell function during the OGTT, significantly blunted prior to RYGBP, normalized to levels of both control groups after RYGBP. In contrast, during the iso-IVGC, β-cell function improved minimally and remained significantly impaired compared to LEAN controls up to 3 years post-RYGBP. Pre-surgery β-cell function, weight loss and GLP-1 response were all predictors of post-surgery β-cell function, although weight loss appeared to be the strongest predictor. These data show that β-cell dysfunction persists after RYGBP, even in patients in clinical diabetes remission. This impairment can be rescued by oral glucose stimulation, suggesting that RYGBP leads to an important gastrointestinal effect, critical for improved β-cell function after surgery.
- Received August 1, 2013.
- Accepted November 22, 2013.
- © 2013 by the American Diabetes Association.
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