Five-year Changes in Body Composition in Type 2 Diabetes Mellitus Patients with a BMI < 32.5 kg/m 2 Undergoing Laparoscopic Roux-en-Y Gastric Bypass Surgery

Purpose Information is scarce on the five-year effect of laparoscopic Roux-en-Y Gastric Bypass (LRYGB) on body composition for Type 2 diabetes mellitus (T2DM) patients with a low BMI. This study aimed to evaluate the five-year changes in body composition in a Chinese T2DM cohort with a BMI < 32.5 kg/m 2 after LRYGB. Methods Twenty-seven T2DM patients were assessed preoperatively (baseline) and 3 months, 6 months, 1 year, 3 years, and 5 years after LRYGB with dual-energy X-ray absorptiometry (DXA). Results DXA assessments were completed in 100%, 85%, 85%, 85%, 48%, and 37% at baseline and 3 months, 6 months, 1 year, 3 years, and 5 years, respectively. For the whole body, fat-free mass and muscle mass decreased from 6 months to 5 years after LRYGB (P < 0.05), while bone mineral content decreased at 5 years after LRYGB (P < 0.05). Fat mass of different regions decreased from 3 months to 1 year (P < 0.05), and a similar magnitude of variation was observed in body fat mass percentage. A fat redistribution characterized by the regional fat proportion of trunk and android decreasing and the regional fat proportion of limbs gaining (P < 0.05) occurred at 5 years after LRYGB. Conclusion For low BMI patients with T2DM, LRYGB led to a short-term reduction in FM and a lasting reduction in FFM. A metabolically healthy fat redistribution occurring 5 years after LRYGB might be a promising mechanism to explain the lasting benefits of LRYGB for T2DM patients with a low BMI. Graphical abstract