Long-term Outcomes of Bariatric Surgery in Patients With Type 2 Diabetes

Gregory A. Nichols, PhD


June 05, 2013

Bariatric Surgery Is Associated With a Reduction in Major Macrovascular and Microvascular Complications in Moderately to Severely Obese Patients With Type 2 Diabetes Mellitus

Johnson BL, Blackhurst DW, Latham BB, et al
J Am Coll Surg. 2013;216:545-556

Study Summary

This large, population-based, retrospective cohort study of adult obese patients with type 2 diabetes compared patients who underwent bariatric surgery with nonbariatric surgery controls. The outcomes of interest were any first major macrovascular event (myocardial infarction, stroke, or all-cause death) or microvascular event (new diagnosis of blindness, laser eye or retinal surgery, nontraumatic amputation, or creation of permanent arteriovenous access for hemodialysis), assessed in combination and separately.

The investigators used traditional multivariable Cox regression analysis to follow patients for up to 9 years. They also reanalyzed the data using propensity score matching to account for nonrandom selection of bariatric surgery. Models were adjusted for demographic characteristics and comorbidities that could be potential confounders.

Bariatric surgery patients were younger and more likely to be women. Although hyperlipidemia was more common among bariatric surgery patients, prevalence of coronary artery disease was less common, as were several manifestations of microvascular disease. After adjustment for baseline differences, bariatric surgery was associated with a 64% reduced risk for the composite of any major macro- or microvascular event, a 61% reduction in macrovascular risk, and a 78% reduction in microvascular risk. Reanalysis with propensity score-based models produced similar results.


Similar to most medical advances, bariatric surgery is increasingly less risky and less radical than it was only 10 years ago. There is now little doubt that the surgery can resolve diabetes in many patients, as well as mitigate other metabolic abnormalities.[1,2] Indeed, bariatric surgery provides better glycemic control than conventional or intensive medical therapy for diabetes.[3,4] However, whether the weight loss and normoglycemia resulting from bariatric surgery lead to reductions in microvascular and macrovascular disease has not previously been reported. This is an especially pertinent question, because the Look AHEAD study was stopped owing to its inability to demonstrate a reduction in the number of cardiovascular events.[5]

In addition to invasiveness, cost is an important factor when considering bariatric surgery. Although some studies have suggested that bariatric surgery is probably cost-effective,[6,7] a key driver of comorbidity and mortality in diabetes is cardiovascular disease. Indeed, avoidance of a single myocardial infarction can "pay" for 2-3 bariatric surgeries. Thus, the current study is potentially important.

However, one must always be cautious with observational data. Despite efforts to statistically and methodologically control for differences between patients who did and did not receive bariatric surgery, we can never be completely assured that selection bias is not a problem. That said, if these results are to be believed, bariatric surgery to cure diabetes and avoid cardiovascular disease may in fact be cost-saving.