Preoperative -cell function in patients with type 2 diabetes is important for the outcome of Roux-en-Y gastric bypass surgery

Roux-en-Y gastric bypass surgery leads to remission of type 2 diabetes in the majority of patients suffering from the disease. The gut hormone glucagon-like peptide-1 is believed to be of major importance for the remission process. The present project demonstrates a marked difference in the chance of remission of type 2 diabetes in patients with low or high preoperative -cell function in spite of a similar post-surgery increase in postprandial glucagon-like peptide-1 release. Furthermore, post-surgery intravenous glucose administration, which does not stimulate release of glucagon-like peptide-1, leads to increased insulin secretion in the patients with the best preoperative -cell function. Together the present findings indicate that patients with type 2 diabetes with high preoperative -cell function experience a glucagon-like peptide-1-independent increase in -cell function after gastric bypass surgery. The majority of the patients with type 2 diabetes (T2DM) show remission after Roux-en-Y gastric bypass (RYGB). This is the result of increased postoperative insulin sensitivity and -cell secretion. The aim of the present study was to elucidate the importance of the preoperative -cell function in T2DM for the chance of remission after RYGB. Fifteen patients with and 18 without T2DM had 25g oral (OGTT) and intravenous (IVGTT) glucose tolerance tests performed at inclusion, after a diet-induced weight loss, and 4 and 18months after RYGB. Postoperative first phase insulin secretion rate (ISR) during the IVGTT and -cell glucose sensitivity during the OGTT increased in T2DM. Postoperative insulin sensitivity and the disposition index (DI) markedly increased in both groups. By stratifying the T2DM into two groups according to highest (T2DM(high)) and lowest (T2DM(low)) baseline DI, a restoration of first phase ISR and -cell glucose sensitivity were seen only in T2DM(high). Remission of type 2 diabetes was 71 and 38% in T2DM(high) and T2DM(low), respectively. Postoperative postprandial GLP-1 concentrations increased markedly, but did not differ between the groups. Our findings emphasize the importance of the preoperative of -cell function for remission of diabetes after RYGB.