Bariatric surgery for type 2 diabetes associated with reduced risk of microvascular disease

Although this retrospective cohort study was limited by its observational design and the risk of confounding by indication, the results should help diabetes patients make informed decisions about their treatment options, the authors said.


Patients with type 2 diabetes who underwent bariatric surgery were less likely to develop microvascular disease than similar patients who didn't have surgery, according to a recent analysis.

The retrospective cohort study included 4,024 patients ages 19 to 79 years who had type 2 diabetes and bariatric surgery between 2005 and 2011. They were matched with up to three nonsurgical control patients based on age, sex, body mass index (BMI), HbA1c level, insulin use, diabetes duration, and intensity of health care use. Follow-up continued through September 2015. Results were published by Annals of Internal Medicine on Aug. 7.

At five years, a significantly smaller percentage of the bariatric surgery patients had developed microvascular disease (16.9% vs. 34.7%; adjusted hazard ratio [HR], 0.41 [95% CI, 0.34 to 0.48]). The difference was primarily driven by a lower incidence of diabetic neuropathy (7.2% vs. 21.4%; HR, 0.37 [95% CI, 0.30 to 0.47]), but there were also significant differences in the rates of nephropathy (4.9% vs. 10.0%; HR, 0.41 [95% CI, 0.29 to 0.58]) and retinopathy (7.2% vs. 11.2%; HR, 0.55 [CI, 0.42 to 0.73]).

Previous research on diabetic retinopathy and bariatric surgery has been mixed, perhaps because rapid decreases in HbA1c level and discontinuation of fenofibrates and angiotensin-receptor blockers after surgery can increase risk for this complication, the authors noted. Although this study was limited by its observational design and the risk of confounding by indication, the results should help diabetes patients make informed decisions about their treatment options, they said. “Not all patients will be interested in bariatric surgery to treat their [type 2 diabetes], but providers should engage all patients with [type 2 diabetes] and a BMI of 35 kg/m2 or higher in a shared decision-making conversation about the benefits and risks of bariatric procedures,” the authors wrote.

An accompanying editorial mentioned the concern that the results may have been affected by which patients choose to have surgery and called for a randomized controlled trial to confirm the findings of this large cohort study. Researchers should also investigate whether nonsurgical treatments that result in equivalent weight loss and metabolic control have a similar effect on microvascular outcomes and whether bariatric surgery can reverse existing microvascular disease. “Bariatric surgery is safe and is, at present, our most evidence-based treatment to put hyperglycemia from [type 2 diabetes] into remission,” the editorial said.