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

by Karen J. Coleman, Sebastien Haneuse, Eric A. Johnson, Andy Bogart, David Fisher, Patrick J. O'Connor, Nancy E. Sherwood, Steve Sidney, Mary Kay Theis, Jane Anau, et al.

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Research Questions

  1. How does remission of type 2 diabetes after bariatric surgery affect a patient's risk of microvascular disease?
  2. 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.

Key Findings

  • 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.

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