Gastric volume reduction is essential for the remission of type 2 diabetes mellitus after bariatric surgery in nonobese rats

Abstract

Background: Roux-en-Y gastric bypass (RYGB) has shown positive outcomes in the remission of type 2 diabetes (T2D) and weight loss in obese patients by inhibiting food intake and nutrient absorption as well as inducing favorable hormonal changes. The purpose of the present study was to investigate whether gastric volume reduction is still required in addition to intestinal bypass for the purpose of T2D remission in nonobese patients.

Setting: University Medical Center.

Methods: Nonobese T2D Goto-Kakizaki rats were employed in the study. All rats were randomized into 3 groups according to the surgical procedure performed, including (1) RYGB, (2) duodeno-jejunal bypass (DJB) without gastric volume reduction, and (3) sham surgery (control). In addition, age-matched Wistar rats were adopted as normal nondiabetic controls. Weight, food intake, fasting plasma glucose, and intraperitoneal glucose tolerance test were measured in vivo before and 2, 4, and 8 weeks after the treatment. Whole body metabolic parameters including respiratory exchange ratio, energy expenditure, and activities were also recorded in all animals at the third week postoperatively.

Results: Compared with DJB and sham animals, the RYGB group had lower weight, less food intake, lower fasting plasma glucose, and improved glucose tolerance at all measuring time points postoperatively. By measuring whole body metabolic parameters, we found that RYGB, but not DJB, increased metabolic rate manifested by increased energy expenditure but less activity at night. In the meantime, respiratory exchange ratio was lower in RYGB group than in the other 3 groups at daytime, meaning adipose tissue became the main source of internal energy production during the resting phase in the group.

Conclusion: For nonobese T2D patients, adding gastric volume reduction to intestine bypass gave better efficacy in remission of T2D by increasing metabolic rate and adipolysis, especially during the resting period.

Keywords: Bariatric surgery; Duodeno-jejunal bypass; Energy expenditure; Roux-en Y gastric bypass; Type 2 diabetes.