Study on the relationship between the short-term changes of body fat and improvement of insulin resistance in obesity after laparoscopic Roux-en-Y gastric bypass surgery

Abstract

Objective To investigate the short-term effects of laparoscopic Roux-en-Y gastric bypass (LRYGB) surgery on body composition and glycolipid metabolism in obese subjects, and to analyze the correlation between body fat changes and insulin resistance improvement. Methods 20 Chinese adults with obesity receiving LRYGB at Department of Bariatric and Metabolic Surgery, The First Affiliated Hospital with Nanjing Medical University were included to this study between Aug 2017 and Oct 2018. The body composition and glycolipid metabolism indexes were analyzed before and 3 months after surgery. Homeostasis model assessment of insulin resistance index (HOMA-IR) was calculated. Results Weight, fasting glucose, fasting insulin (FINS), HbA1c and total triglycerides (TG) decreased significantly 3 months after surgery (P<0.05). HOMA-IR decreased from (7.70±4.17) to (2.63±1.52). The abdominal obesity indexes, including waist circumference, waist-hip ratio and visceral fat area were remarkably decreased (P<0.05). The body fat decreased from (47.89±13.01) kg to (30.40±10.89) kg, and the body fat percentage decreased from (43.11±1.27) % to (34.89±1.77) %. After 3 months postoperatively, the reduction of body fat was an independent factor affecting the improvement of HOMA-IR and FINS (HOMA-IR, r=0.58, P=0.007; FINS, r=0.69, P=0.001), while the improvement of HbA1c was independently and positively correlated with the reduction of waist-hip ratio (r=0.48, P=0.031). Meanwhile, the decrease of visceral fat area was independently and positively correlated with the change of TG (r=0.53, P=0.016). Conclusions Apart from reduction in weight, waist circumference and waist-hip ratio, the levels of body fat, body fat percentage and visceral fat area also decreased significantly in obesity in the short term after LRYGB. Moreover, the variation of body fat was an independent factor affecting the improvement of HOMA-IR after surgery, and the short-term change of waist-hip ratio was strongly associated with reduced HbA1c. In the early stage after the LRYGB procedure, by regulating the distribution of body fat, it may lead to a decrease in insulin resistance and an improvement in the benefit of glycolipid metabolism. Key words: Laparoscopic Roux-en-Y gastric bypass; Obesity; Type 2 diabetes mellitus; Body fat distribution; Insulin resistance