In a new study published in JAMA Surgery,  investigators reported that Roux-en-Y gastric bypass maintained significant differences from lifestyle and medical management in outcomes after 5-year in obese adults with type 2 diabetes, but with diminishing effectiveness.

The Roux-en-Y gastric bypass is effective in achieving established diabetes treatment targets, but durability is unknown. The current study objective was to compare the durability of Roux-en-Y gastric bypass added to intensive lifestyle and medical management in achieving diabetes control targets.

Observational follow-up of a randomized clinical trial at 4 sites in the United States and Taiwan, involving 120 participants who had a haemoglobin A1c (HbA1c) level of 8.0% or higher and a body mass index between 30.0 and 39.9 were followed up for 5 years.

Lifestyle-intensive medical management intervention based on the Diabetes Prevention Program and LookAHEAD trials for 2 years, with and without (60 participants each) Roux-en-Y gastric bypass surgery followed by observation to year 5.

The American Diabetes Association composite triple endpoint of haemoglobin A1c less than 7.0%, low-density lipoprotein cholesterol less than 100 mg/dL, and systolic blood pressure less than 130 mm Hg at 5 years.

Of 120 participants who were initially randomized (mean age, 49 years), 98 (82%) completed 5 years of follow-up. Baseline characteristics were similar between groups: mean (SD) body mass index 34.4 for the lifestyle-medical management group and 34.9 for the gastric bypass group and had haemoglobin A1c levels of 9.6% and 9.6%, respectively.

At 5 years, 13 participants in the gastric bypass group and 2 in the lifestyle-intensive medical management group had achieved the composite triple endpoint. In the fifth year, 31 patients in the gastric bypass group vs 8 in the lifestyle-medical management group achieved an HbA1c level of less than 7.0%.

Gastric bypass had more serious adverse events than did the lifestyle-medical management intervention, 66 events vs 38 events, most frequently gastrointestinal events and surgical complications such as strictures, small bowel obstructions, and leaks. Gastric bypass had more parathyroid hormone elevation but no difference in B12 deficiency.

In an extended follow-up of obese adults with type 2 diabetes randomized to adding gastric bypass compared with lifestyle and intensive medical management alone, there remained a significantly better composite triple endpoint in the surgical group at 5 years. However, because the effect size diminished over 5 years, further follow-up is needed to understand the durability of the improvement.