In the Journals

Bariatric surgery linked with lower BMD, bone mineral content

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July 20, 2015

Adults with type 2 diabetes undergoing bariatric surgery are likely to experience reductions in lean mass, bone mineral content and bone mineral density, even with calcium and vitamin D supplementation, according to research in Obesity.

In a 2-year follow-up study of the STAMPEDE trial, researchers found that adults with obesity and type 2 diabetes who underwent either gastric bypass or sleeve gastrectomy were more likely to experience a reduction in both bone mineral content and BMD compared with those who received intensive medical therapy, but no surgery.

Sangeeta Kashyap , MD, of the Cleveland Clinic, and colleagues analyzed data from 54 adults with type 2 diabetes and obesity (mean age, 48 years; mean BMI, 36 kg/m²; 59% women; 72% white) randomized to receive either gastric bypass surgery (n = 18), sleeve gastrectomy (n = 19) or intensive medical therapy (n = 17).

Sangeeta Kashyap

Sangeeta Kashyap

All participants underwent DXA before and after randomization for total lean mass, bone mineral content and BMD measurements, and researchers assigned all participants calcium and vitamin D supplementation. Researchers obtained serum leptin and adiponectin levels at baseline, 12 and 24 months.

Two years after randomization, researchers found that total bone mineral content decreased 8.2% in the gastric bypass group and by 6.6% in the sleeve gastrectomy group, compared with a 0.3% reduction in the medical therapy group. Total hip BMD also decreased, with a 9.5% reduction in the gastric bypass group and a 9.2% reduction in the sleeve gastrectomy group.

Researchers found the change in hip BMD correlated to weight loss, changes in lean mass and leptin (P <.0001 for each).

In addition, four participants in the gastric bypass group and two participants in the sleeve gastrectomy group reported peripheral fractures, as well as four participants in the medical therapy group.

“Despite the lack of change in bone mineral content and density in [the medical therapy group], there were similar fracture rates in this group as compared with [the gastric bypass group],” the researchers wrote.

Researchers noted that as many as 60% of patients with morbid obesity are deficient in vitamin D, putting them at a greater risk for developing postoperative deficiencies in bone mineral content and BMD that are difficult to correct even with vitamin D supplementation.

Researchers said future studies are needed to investigate the long-term effects of bariatric surgery on BMD and calcium metabolism, in order to better understand the clinical implications of bone loss on patients undergoing weight loss surgery. by Regina Schaffer

Disclosure: Kashyap reports various financial ties with the American Diabetes Association, Ethicon Endo-surgery and NIH. Please see the full study for all other authors’ relevant financial disclosures.

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