Does Weight Loss Surgery Help People with Type 2 Diabetes in the Long Term?
A large 2026 Cochrane review looked at whether weight loss surgery leads to better long-term outcomes for people living with both obesity and type 2 diabetes compared with non-surgical treatment. It found that several surgical procedures, including the one anastomosis gastric bypass, may lead to greater weight loss and improved blood sugar control over the long term.
The Review Looked at 18 Studies and More Than 15,000 Adults
Researchers pooled data from 18 studies involving 15,282 adults who had obesity and type 2 diabetes, with follow-up periods of at least three years. The studies compared different types of weight loss surgery against each other and against non-surgical approaches such as lifestyle changes and medical treatment. Surgical procedures examined included the one anastomosis gastric bypass (sometimes called OAGB, a form of stomach bypass), the Roux-en-Y gastric bypass (another bypass technique), and the gastric sleeve (where a portion of the stomach is removed to reduce its size).
Surgery Was Associated with Greater Weight Loss and Better Blood Sugar Levels
The one anastomosis gastric bypass was associated with around 12 percent greater long-term weight loss compared with lifestyle and medical treatment alone. All three surgical procedures were also linked to improvements in HbA1c, which is a blood test that reflects average blood sugar levels over several months. There were also signs that surgery may support partial remission of type 2 diabetes, meaning blood sugar levels improve significantly, though the evidence for many of these findings was rated as very uncertain by the researchers.
The Findings Are Promising but Some Uncertainty Remains
The review drew on studies from multiple countries, which strengthens its reach, but the number of participants in some parts of the analysis was relatively small, which limits how confident we can be in certain results. The researchers noted that larger and better-designed studies are needed to confirm these findings. Results also vary from person to person, so individual outcomes will differ.
About this research: Metabolic and bariatric surgery in adults with obesity and diabetes mellitus: a network meta-analysis, The Cochrane Database of Systematic Reviews, 2026. Read the study summary
More detail about this procedure is on our one anastomosis gastric bypass page. If you are considering your options, call us on (03) 9760 2777 or request an appointment through our website.