LAUSR

Background To compare changes in bone mineral density (BMD) in patients with morbid obesity and type 2 diabetes (T2D) a year after being randomized to metabolic gastric bypass (mRYGB), sleeve gastrectomy (SG), and greater curvature plication (GCP). We also analyzed the association of gastrointestinal hormones with skeletal metabolism. Methods Forty-five patients with T2D (mean BMI 39.4 ± 1.9 kg/m 2 ) were randomly assigned to mRYGB, SG, or GCP. Before and 12 months after surgery, anthropometric, body composition, biochemical parameters, fasting plasma glucagon, ghrelin, and PYY as well as GLP-1, GLP-2, and insulin after a standard meal were determined. Results After surgery, the decrease at femoral neck (FN) was similar but at lumbar spine (LS), it was greater in the mRYGB group compared with SG and GCP − 7.29 (4.6) vs. − 0.48 (3.9) vs. − 1.2 (2.7)%, p  < 0.001. Osteocalcin and alkaline phosphatase increased more after mRYGB. Bone mineral content (BMC) at the LS after surgery correlated with fasting ghrelin ( r  = − 0.412, p  = 0.01) and AUC for GLP-1 ( r  = − 0.402, p  = 0.017). FN BMD at 12 months correlated with post-surgical fasting glucagon ( r  = 0.498, p  = 0.04) and insulin AUC ( r  = 0.384, p  = 0.030) and at LS with the AUC for GLP-1 in the same time period ( r  = − 0.335, p  = 0.049). However, in the multiple regression analysis after adjusting for age, sex, and BMI, the type of surgery (mRYGB) remained the only factor associated with BMD reduction at LS and FN. Conclusions mRYGB induces greater deleterious effects on the bone at LS compared with SG and GCP, and gastrointestinal hormones do not play a major role in bone changes.