['Bariatric surgery offers successful resolution of type 2 diabetes mellitus (T2DM). However, recurrence of T2DM has been observed in a number of patients with initial resolution after bariatric surgery. This study aimed to induce reversal of the improvement of diabetes in T2DM rats after duodenal-jejunal bypass (DJB), and identify the effects of weight changes and gut hormones that might be involved.', 'DJB surgery was performed in two T2DM rat models (n=20 for each group): non-obese Goto-Kakizaki (GK) rats, and moderately-obese T2DM rats induced by a combination of a high-fat diet (HFD) and low-dose streptozotocin (HS rats). The controls were sham-operated and non-treated rats. All rats were then randomly divided into HFD- and low-fat diet (LFD)-fed groups. Glucose tolerance, insulin tolerance, glucose-stimulated insulin, glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) secretion, food intake and body weight were measured and compared with controls.', 'DJB surgery resulted in a significant improvement in glucose tolerance in both GK and HS rats fed with either HFD or LFD. In contrast to LFD-fed rats, improved glucose tolerance was impaired in GK and HS rats fed with an HFD, accompanied by re-impairment of insulin tolerance and failure in enhancement of insulin secretion. There was no significant difference in food intake and body weight between DJB-operated and control rats, and between HFD- and LFD-fed rats. Glucose-stimulated GLP-1 and PYY levels were significantly increased after DJB surgery; however, they were not significantly different between HFD- and LFD-fed rats.'] Does a high-fat diet reverse improvement in glucose tolerance induced by duodenal-jejunal bypass in type 2 diabetic rats?