Long-term microvascular disease outcomes in patients with type 2 diabetes after bariatric surgery: Evidence for the legacy effect of surgery

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.