BACKGROUND: Roux-en-Y gastric bypass (RYGB) has been associated with negative effects on bone. Whether this association is affected by pre-surgical type 2 diabetes (T2D) and surgically induced diabetes remission is unknown.

METHODS: In this cross-sectional, matched cohort study 6 years after RYGB, we investigated bone health in 96 individuals with body mass index (BMI) > 35 kg/m2 and T2D (stratified on current diabetes status) treated by RYGB 6 years earlier compared with 49 non-operated individuals with T2D matched with respect to sex, age, and current BMI. Main outcome measures were areal and volumetric bone mineral density (aBMD and vBMD), bone turnover, and odds ratio of osteoporosis/osteopenia.

RESULTS: The RYGB group had lower hip (0.916 vs 1.010 g/cm2, p < 0.001), forearm (0.497 g/cm2 vs 0.554 g/cm2, p < 0.001) aBMD, (269.63 mg/cm3 vs 306.07 mg/cm3, p < 0.001) tibial, and radial (238.57 mg/cm3 vs 278.14 mg/cm3, p < 0.0001) vBMD than the control group. Relative to the control group, c-terminal cross-linked telopeptide, procollagen type I amino-terminal propeptide, and osteocalcin were 75%, 41%, and 72% higher in the RYGB group, respectively (all p < 0.001). Odds ratio for osteopenia/osteoporosis in operated individuals was 2.21 (95% CI 1.06; 4.79, p = 0.05). Overall, stratified analysis on current diabetes status did not alter these outcomes.

CONCLUSIONS: Individuals with T2D treated by RYGB, compared to individuals with T2D of similar age and body composition not treated by RYGB, have lower BMD, lower bone strength, and increased levels of several bone turnover markers. Bone health was not associated with current diabetes status in the RYGB group.