Bariatric surgery and the neurohormonal switch: Early insulin resistance recordings after laparoscopic sleeve gastrectomy

Laparoscopic sleeve gastrectomy (LSG) is a bariatric operation with a safe risk profile. It has been proven to successfully reduce weight, decrease insulin resistance (IR), and ameliorate diabetes mellitus. The aim of this study was to determine if there is an early improvement in IR after LSG and its association with weight loss. This was a prospective observational study of 32 patients who underwent LSG at a single center over a 3-year period. Serum insulin and fasting glucose levels were recorded preoperatively, on day 1 postoperatively, and 3 weeks after LSG. IR levels were calculated using the Homeostasis Model Assessment 2 Version 2.23. IR levels were compared along with the overall weight loss, via body mass index. beta-cell function was the secondary outcome. IR significantly improved the day after surgery with a statistically significant mean difference of 0.89 units (P = .043) and significantly more so 3 weeks postoperatively, with a mean difference of 4.32 units (P < .0005). beta-cell function reduced 3 weeks postoperatively, with a mean difference of 23.95 %beta (P = .025), while body mass index significantly reduced, with a mean difference of 4.32 kg/m(2) (P < .0005). Early improvement of IR was observed on postoperative day 1 after LSG before any weight loss. This raises the possibility of an undetermined, underlying neurohormonal switch that improves IR. Further investigation is needed to determine this mechanism, as it may lead to an improvement in the medical management of diabetes mellitus.