Effect of gastric bypass versus sleeve gastrectomy on the remission of type 2 diabetes, weight loss, and cardiovascular risk factors at 5 years (Oseberg): secondary outcomes of a single-centre, triple-blind, randomised controlled trial

Abstract

Background: For individuals with obesity and type 2 diabetes, weight loss improves insulin sensitivity and β-cell function and can induce remission of diabetes. However, the long-term comparative effectiveness of standard gastric bypass and sleeve gastrectomy on remission of type 2 diabetes remains unclear. We aimed to compare the effects of gastric bypass and sleeve gastrectomy on type 2 diabetes remission, weight loss, and cardiovascular risk factors 5 years after surgery.

Methods: We present a secondary analysis of a two-armed, single-centre, triple-blind, randomised controlled trial conducted at a public tertiary obesity centre in Norway. Adults (ie, age ≥18 years) with type 2 diabetes and obesity were randomly assigned (1:1) by a computerised random number generator to laparoscopic gastric bypass or sleeve gastrectomy, with balanced block sizes of ten. Study personnel, participants, and the primary-outcome assessor were all masked to the allocation until 1 year after surgery, after which further follow-up was open label. Changes in key secondary outcomes, including type 2 diabetes remission, weight loss, and cardiovascular risk factors, were assessed 5 years after surgery. The trial procedure estimand assessed treatment effects in all randomised participants, with data collected after conversional surgery removed from analyses. The trial was registered with ClinicalTrials.gov (NCT01778738) and was completed in December, 2022.

Findings: Between Oct 15, 2012, and Sept 1, 2017, 319 patients were assessed for eligibility, resulting in 109 participants who were randomly assigned to gastric bypass (n=54) or sleeve gastrectomy (n=55). The baseline mean age was 47·7 years (SD 9·6), mean BMI 42·3 kg/m² (SD 5·3), 72 (66%) were women, and 37 (34%) were men. 93 (85%) participants completed 5-year follow-up (47 [85%] in the sleeve gastrectomy group and 46 [85%] in the gastric bypass group). The proportions with remission of type 2 diabetes were higher after gastric bypass than after sleeve gastrectomy (HbA_1c ≤6·0% 23 [50%] of 46 vs nine [20%] of 44, risk difference 29·5% [95% CI 10·8 to 48·3]; HbA_1c <6·5% 29 [63%] vs 13 [30%], risk difference 33·5% [14·1 to 52·9]). Gastric bypass provided greater loss in bodyweight (mean 22·2% [95% CI 20·3 to 24·1] vs 17·2% [15·3 to 19·1], treatment difference 5·0% [2·4 to 7·7]) and lower LDL-cholesterol (treatment difference -0·5 mmol/L [-0·8 to -0·1]). The prevalence of erosive oesophagitis and Barrett's oesophagus was similar between groups, whereas pathological acid reflux occurred more frequently after sleeve gastrectomy (risk difference 51·1% [28·0 to 74·2]). More participants had symptomatic postprandial hypoglycaemia after gastric bypass than after sleeve gastrectomy (15 [28%] vs one [2%]).

Interpretation: Gastric bypass was superior to sleeve gastrectomy regarding long-term remission of type 2 diabetes, weight loss, and LDL cholesterol concentrations, at the expense of a higher frequency of symptomatic postprandial hypoglycaemia. These findings could inform clinical practice and future guidelines regarding the preferred surgical procedure in patients with type 2 diabetes.

Funding: Vestfold Hospital Trust.

Translation: For the Norwegian translation of the abstract see Supplementary Materials section.