Gastric bypass versus sleeve gastrectomy in patients with type 2 diabetes (Oseberg): a single-centre, triple-blind, randomised controlled trial

Background: The comparative effectiveness of various bariatric procedures on remission of type 2 diabetes remains debated. We aimed to compare the two most commonly used procedures, hypothesising higher remission rates of diabetes after gastric bypass than after sleeve gastrectomy. Methods: The Oseberg study is an ongoing triple-blind, randomised, single-centre trial taking place at Vestfold Hospital Trust, Norway. Adult patients with type 2 diabetes and obesity were randomly assigned (1:1) to receive either gastric bypass or sleeve gastrectomy. Randomisation was performed with a computerised random number generator using block sizes of 10. Treatment allocation was concealed using sealed opaque envelopes, and was masked from participants, study personnel and outcome assessors. Primary outcomes were, first, the proportion of participants with complete remission of diabetes; glycated haemoglobin 6·0% (42 mmol/mol) or less with no diabetes medication, and, second, beta-cell function modelled from an intravenous glucose tolerance test at one year. Analyses were performed according to intention-to-treat and per-protocol principles. The trial is registered at ClinicalTrials.gov with identifier: NCT01778738. Findings: Between January 28, 2013 and February 4, 2018, 109 patients were randomly assigned to gastric bypass (n=54) or sleeve gastrectomy (n=55), with a total of 107 (98%) patients completing 1-year follow-up. Remission of diabetes occurred in 40/53 patients (75%) in the gastric bypass-group and 26/54 patients (48%) in the sleeve gastrectomy-group; risk ratio 1·57, 95% CI 1·14–2·15; p=0·0036. Beta-cell function increased 6- to 7-fold from baseline, with no differences between groups. The number of early and late complications after gastric bypass and sleeve gastrectomy were 10 versus 8 and 17 versus 22, respectively. Interpretation: Gastric bypass being found to be superior to sleeve gastrectomy for remission of type 2 diabetes might have important individual and societal implications, including the potential to improve diabetes care and reduce related societal costs