Original article| Volume 17, ISSUE 6, P1049-1056, June 2021

Long-term impact of bariatric surgery on glycemic control and glucose-lowering therapy for people with type 2 diabetes: population-based cohort study

Published:February 17, 2021DOI:


      • Bariatric surgery lowers A1c in real-world clinical care.
      • Improvements are sustained for at least 6 years.
      • Benefits were greatest for younger people and those with shorter diabetes duration.
      • Therefore, efficacy results from RCTs are generalizable to routine clinical practice.



      Randomized controlled trials (RCTs) have demonstrated that bariatric surgery improves glycemic control among people with diabetes. However, evidence from RCTs may not be generalizable to real-world clinical care with unselected patients in routine clinical practice.


      To examine long-term glycemic control and glucose-lowering drug regimens following bariatric surgery for people with type 2 diabetes (T2D) in unselected patients in routine clinical practice.


      Population-based cohort study using linked routinely collected real-world data from Ontario, Canada.


      Individuals with T2D who were assessed for bariatric surgery at any referral center in the province between February 2010 and November 2016 were identified and divided into those who received surgery within 2 years of the initial assessment and those who did not.


      There were 3674 people who had bariatric surgery and 1335 who did not. By 2 years, people who had undergone surgery had a significantly lower HbA1C (6.3 ± 1.2 % versus 7.8 ± 1.8 %, P < .0001), and this difference persisted at 3, 4, 5, and 6 years. Even by 6 years, half of those who had undergone surgery remained on no glucose-lowering drugs, and they were nearly 6 times less likely to be on insulin than those who had not undergone surgery.


      In real-world clinical care, bariatric surgery was associated with large and sustained improvements in glycemic control.

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