Background: For patients with obesity and type 2 diabetes, weight loss improves insulin sensitivity and β-cell function, and can induce remission of diabetes. The comparative efficacy of various bariatric procedures for the remission of type 2 diabetes has not been fully elucidated. We aimed to compare the effects of the two most common bariatric procedures, gastric bypass and sleeve gastrectomy, on remission of diabetes and β-cell function.
Methods: We conducted a single-centre, triple-blind, randomised trial at Vestfold Hospital Trust (Tønsberg, Norway), in which patients (aged ≥18 years) with type 2 diabetes and obesity were randomly assigned (1:1) to receive gastric bypass or sleeve gastrectomy (the Oseberg study). Randomisation was performed with a computerised random number generator and a block size of 10. Treatment allocation was masked from participants, study personnel, and outcome assessors and was concealed with sealed opaque envelopes. Surgeons used identical skin incisions during both surgeries and were not involved in patient follow-up. The primary clinical outcome was the proportion of participants with complete remission of type 2 diabetes (HbA1c of ≤6·0% [42 mmol/mol] without the use of glucose-lowering medication) at 1 year after surgery. The primary physiological outcome was disposition index (a measure of β-cell function) at 1 year after surgery, as assessed by an intravenous glucose tolerance test. Primary outcomes were analysed in the intention-to-treat and per-protocol populations. This trial is ongoing and closed to recruitment, and is registered with ClinicalTrials.gov, NCT01778738.
Findings: Between Oct 15, 2012, and Sept 1, 2017, 1305 patients who were preparing for bariatric surgery were screened, of whom 319 consecutive patients with type 2 diabetes were assessed for eligibility. 109 patients were enrolled and randomly assigned to gastric bypass (n=54) or sleeve gastrectomy (n=55). 107 (98%) of 109 patients completed 1-year follow-up, with one patient in each group withdrawing after surgery (per-protocol population). In the intention-to-treat population, diabetes remission rates were higher in the gastric bypass group than in the sleeve gastrectomy group (risk difference 27% [95% CI 10 to 44]; relative risk [RR] 1·57 [1·14 to 2·16], p=0·0054); results were similar in the per-protocol population (risk difference 27% [95% CI 10 to 45]; RR 1·57 [1·14 to 2·15], p=0·0036). In the intention-to-treat population, disposition index increased in both groups (between-group difference 55 [-111 to 220], p=0·52); results were similar in the per-protocol population (between-group difference 21 [-214 to 256], p=0.86). In the gastric bypass group, ten of 54 participants had early complications and 17 of 53 had late side-effects. In the sleeve gastrectomy group, eight of 55 participants had early complications and 22 of 54 had late side-effects. No deaths occurred in either group.
Interpretation: Gastric bypass was found to be superior to sleeve gastrectomy for remission of type 2 diabetes at 1 year after surgery, and the two procedures had a similar beneficial effect on β-cell function. The use of gastric bypass as the preferred bariatric procedure for patients with obesity and type 2 diabetes could improve diabetes care and reduce related societal costs.
Funding: Morbid Obesity Centre, Vestfold Hospital Trust.
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