Single-centre, triple-blinded, randomised, 1-year, parallel-group, superiority study to compare the effects of Roux-en-Y gastric bypass and sleeve gastrectomy on remission of type 2 diabetes and β-cell function in subjects with morbid obesity: a protocol for the Obesity surgery in Tønsberg (Oseberg) study

INTRODUCTION: Bariatric surgery is increasingly recognised as an effective treatment option for subjects with type 2 diabetes and obesity; however, there is no conclusive evidence on the superiority of Roux-en-Y gastric bypass or sleeve gastrectomy. The Oseberg study was designed to compare the effects of gastric bypass and sleeve gastrectomy on remission of type 2 diabetes and β-cell function. METHODS AND ANALYSIS: Single-centre, randomised, triple-blinded, two-armed superiority trial carried out at the Morbid Obesity Centre at Vestfold Hospital Trust in Norway. Eligible patients with type 2 diabetes and obesity were randomly allocated in a 1:1 ratio to either gastric bypass or sleeve gastrectomy. The primary outcome measures are (1) the proportion of participants with complete remission of type 2 diabetes (HbA1c≤6.0% in the absence of blood glucose-lowering pharmacologic therapy) and (2) β-cell function expressed by the disposition index (calculated using the frequently sampled intravenous glucose tolerance test with minimal model analysis) 1 year after surgery. ETHICS AND DISSEMINATION: The protocol of the current study was reviewed and approved by the regional ethics committee on 12 September 2012 (ref: 2012/1427/REK sør-øst B). The results will be disseminated to academic and health professional audiences and the public via publications in international peer-reviewed journals and conferences. Participants will receive a summary of the main findings. TRIAL REGISTRATION NUMBER: NCT01778738;Pre-results.