Impact of preoperative NAFLD status on restoration of pancreatic β-cell function after laparoscopic sleeve gastrectomy.

Although pancreatic beta-cell insufficiency is ameliorated after bariatric and metabolic surgery in subjects with obesity and type 2 diabetes (T2D), the mechanism and preoperative factors related to this amelioration have been uncertain. This study investigated the effect of laparoscopic sleeve gastrectomy (LSG) on beta-cell function. The preoperative characteristics and factors associated with the degree of postoperative changes in beta-cell function in those subjects were explored as well. In this sub-analysis of our prospective observational study, subjects with obesity and T2D underwent oral glucose tolerance tests (OGTT) and magnetic resonance imaging (MRI), at the baseline and the end of the 1-year follow-up period. Beta-cell function was evaluated by the insulin secretion-sensitivity index-2 (ISSI-2) and disposition index (DI), and the preoperative factors associated with these changes were examined. In 18 eligible subjects, glucose tolerance improved, ISSI-2 increased significantly, and DI also tended to increase 1 year after LSG. The change in ISSI-2 correlated with preoperative liver fibrosis assessed by MR elastography (r=-0.49, P<0.05). In 16 subjects without severe fibrosis, changes in DI correlated with preoperative MRI-estimated proton density fat fraction (r=-0.52, P<0.05). Neither as glycemic control nor visceral fat were significantly associated with the degree of amelioration in beta-cell function. Pancreatic beta-cell function improved at 1 year postoperative to LSG in subjects with obesity and T2D. Preoperative liver fibrosis and steatosis were associated with a lower degree of postoperative pancreatic beta-cell improvement.