Long-term Microvascular Disease Outcomes in Patients with Type 2 Diabetes After Bariatric Surgery
Evidence for the Legacy Effect of Surgery
Published in: Diabetes Care, 2016
Posted on RAND.org on July 28, 2016
- How does remission of type 2 diabetes after bariatric surgery affect a patient's risk of microvascular disease?
- Does time spent in remission provide a "legacy effect" of protection from microvascular disease if a patient's diabetes relapses?
OBJECTIVE: To identify and quantify any legacy effect of bariatric surgery on risk of incident microvascular disease in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: We conducted a retrospective observational cohort study (n = 4,683; 40% racial/ethnic minority) of patients with type 2 diabetes who underwent bariatric surgery from 2001 through 2011. The primary outcome measure was incident microvascular disease defined as a composite indicator of the first occurrence of retinopathy, neuropathy, and/or nephropathy. The Cox proportional hazards framework was used to investigate the associations between type 2 diabetes remission/relapse status and time to microvascular disease. RESULTS: Covariate-adjusted analyses showed that patients who experienced type 2 diabetes remission had 29% lower risk of incident microvascular disease compared with patients who never remitted (hazard ratio [HR] 0.71 [95% CI 0.60, 0.85]). Among patients who experienced a relapse after remission, the length of time spent in remission was inversely related to the risk of incident microvascular disease; for every additional year of time spent in remission prior to relapse, the risk of microvascular disease was reduced by 19% (HR 0.81 [95% CI 0.67, 0.99]) compared with patients who never remitted. CONCLUSIONS: Our results indicate that remission of type 2 diabetes after bariatric surgery confers benefits for risk of incident microvascular disease even if patients eventually experience a relapse of their type 2 diabetes. This provides support for a legacy effect of bariatric surgery, where even a transient period of surgically induced type 2 diabetes remission is associated with lower long-term microvascular disease risk.
- Type 2 diabetes patients' risk of developing microvascular disease was 29 percent lower if their diabetes went into remission after bariatric surgery than if they did not experience remission.
- The greatest reduction in risk—36.5 percent—was shown for retinopathy at 7 years following bariatric surgery.
- The amount of time a patient spent in remission affected the risk reduction: each additional year in remission corresponded to a 19% lower risk of developing microvascular disease.
- The protective, or legacy, effect of remission was attenuated in patients whose HbA1c levels were higher and who experienced type 2 diabetes for longer periods before surgery.