Around three-quarters of people with type 2 diabetes mellitus (T2DM) who undergo Roux-en-Y gastric bypass experience remission of their disease within a year of the surgery, according to published findings from a population-based observational study. However, one in four of those people will have relapsed by 5 years, the authors noted.

Researchers looked at the effect of Roux-en-Y gastric bypass (RYGB) in 1,111 individuals with T2DM, compared with 1,074 controls who also had T2DM but did not undergo gastric bypass.

By 6 months after surgery, 65% of those who had undergone RYGB met the criteria for remission – defined as no use of glucose-lowering drugs and an HbA1c below 48 mmol/mol (less than 6.5%) or metformin monotherapy with HbA1c below 42 mmol/mol (less than 6.0%).

By 1 year, 74% of those who had surgery had achieved remission, and 73% of those remained in remission 5 years after surgery. However, at 2 years, 6% of those who had achieved remission in the first year had already relapsed; by 3 years, 12% had relapsed; and by 4 years, 18% had relapsed. By 5 years after surgery, a total of 27% of those who originally achieved remission in the first year had relapsed.

The overall prevalence of remission remained at 70% for every 6-month period during the duration of the study, which suggests that, although some achieved remission early and then relapsed, others achieved remission later.

Individuals who were aged 50-60 years were 12% less likely to achieve remission, compared with those who were younger than 40 years, whereas those aged 60 years or more were 17% less likely to achieve remission.

A longer duration of diabetes was also associated with a lower likelihood of achieving remission after RYGB; individuals who had had diabetes for 8 years or more had a 27% lower likelihood of remission, compared with those who had had the disease for less than 2 years.

A higher HbA1c (greater than 53 mmol/mol) was associated with a 19% lower likelihood of remission, and individuals using insulin had a 43% lower likelihood of remission.

“Overall, our findings add evidence to the importance of regular check-ups following RYGB, despite initial diabetes remission, and also suggest that timing of RYGB is important (i.e., consider RYGB while there are still functional pancreatic beta cells),” wrote Lene R. Madsen, MD, from the department of endocrinology and internal medicine at Aarhus (Denmark) University Hospital and her colleagues.

The study also examined the effect of RYGB on microvascular and macrovascular diabetes complications. This revealed that the incidence of diabetic retinopathy was nearly halved among individuals who had undergone gastric bypass, the incidence of hospital-coded diabetic kidney disease was 46% lower, and the incidence of diabetic neuropathy was 16% lower.

In particular, individuals who achieved remission in the first year after surgery had a 57% lower incidence of microvascular events, compared with those who did not have surgery.

The authors noted that individuals who did not reach the threshold for diabetes remission after surgery still showed signs of better glycemic control, compared with individuals who had not undergone surgery.

“This aligns with the theory of ‘metabolic memory’ introduced by Coleman et al. [Diabetes Care. 2016;39(8):1400-07], suggesting that time spent in diabetes remission after RYGB is not spent in vain when it comes to reducing the risk of subsequent microvascular complications,” they wrote.

The surgery was also associated with a 46% reduction in the incidence of ischemic heart disease. In the first 30 days after surgery, 7.5% of patients were readmitted to hospital for any surgical complication, but the 90-day mortality rate after surgery was less than 0.5%.

The study was supported by the Health Research Fund of Central Denmark, the Novo Nordisk Foundation, and the A.P. Møller Foundation. The authors reported no conflicts of interest.

SOURCE: Madsen LR et al. Diabetologia. 2019, Feb 6. doi: 10.1007/s00125-019-4816-2.