Bone material strength increases 1 year after gastric bypass

At 1 year following Roux-en-Y gastric bypass (RYGB), patients may see an improvement in bone material strength despite an increase in bone turnover and a decline in areal bone mineral density (aBMD), a recent study has found. While this trend is similar in those with and without type 2 diabetes (T2D), improved glucose control is associated with increased bone material strength among T2D patients.

Researchers looked at 34 participants who underwent RYGB, among whom 13 had T2D (median duration, 4 years). Of the patients with T2D, eight (62 percent) were treated with one or more oral glucose-lowering drugs and one received both insulin and oral antidiabetic drug.

Preoperative bone material strength index (BMSi) had an inverse association with body mass index (BMI; p=0.010), and this association remained significant despite controlling for age and gender. One year after RYGB, the participants shed a mean of 33.9 kg in weight and 48.7 percent in total body fat and increased physical activity. Vitamin D levels remained unchanged, and only one patient with T2D was in remission.

Specifically, BMSi increased from 78.1 preoperatively to 82.0 at 1 year after RYGB, corresponding to an increase of 4.0 in absolute units or 6.3 percent (p=0.037). The increase was comparable in participants with and without T2D.

In patients with T2D, a greater decrease in HbA1c correlated with a larger increase in BMSi (p=0.019). Bone turnover markers, namely CTX-1 and PINP, increased by 195.1 percent and 109.5 percent, respectively.

Meanwhile, aBMD decreased by 3.9 percent in the lumbar spine, 8.2 percent in the femoral neck, 11.6 percent in total hip and 9.4 percent in total body.

The present data support the hypothesis that higher BMI is associated with reduced bone material strength, as well as show that surgically induced weight loss exerts a positive effect on bone quality.