Effect of Roux-en-Y gastric bypass surgery on diabetes remission and complications in individuals with type 2 diabetes: a Danish population-based matched cohort study.

Aims/hypothesis: The aim of this study was to examine the effect of Roux-en-Y gastric bypass (RYGB) surgery on diabetes remission, subsequent diabetes relapse and micro- and macrovascular complications in individuals with type 2 diabetes and obesity (BMI >35 kg/m ² ) in a real-world setting.
Methods: This was a population-based cohort study of 1111 individuals with type 2 diabetes treated by RYGB at hospitals in Northern Denmark (2006-2015), and 1074 matched non-operated individuals with type 2 diabetes. Diabetes remission was defined as no glucose-lowering drug use with HbA _1c <48 mmol/mol (<6.5%), or metformin monotherapy with HbA _1c <42 mmol/mol (<6.0%). Data on complications were ascertained from medical registries with complete follow-up.
Results: At 1 year of follow-up, 74% of the cohort treated by RYGB experienced diabetes remission, while 27% had relapsed after 5 years. Predictors of non-remission were age >50 years, diabetes duration >5 years, use of glucose-lowering drugs other than metformin, and baseline HbA _1c >53 mmol/mol (>7.0%). Compared with the non-operated cohort using adjusted Cox regression (5.3 years follow-up), the cohort treated by RYGB had 47% lower risk of microvascular complications (HR 0.53 [95% CI 0.38, 0.73]) and a statistically non-significant 24% lower risk of macrovascular complications (HR 0.76 [95% CI 0.49, 1.18]). Diabetes remission vs non-remission at 1 year was associated with reduced HR of 0.43 (95% CI 0.25, 0.72) for microvascular complications and with HR of 0.76 (95% CI 0.40, 1.45) for macrovascular complications.
Conclusions/interpretation: In routine clinical care, three out of four individuals with type 2 diabetes and obesity treated by RYGB experienced diabetes remission after 1 year, whereas 27% of these individuals had relapsed at 5 years follow-up. RYGB was associated with substantially decreased risk of microvascular complications and non-significantly fewer macrovascular complications, with early diabetes remission as a clear predictor of reduced microvascular complications.