Bariatric surgeries have been previously shown to improve glycemic control and may even lead to remission among patients with diabetes.¹ While gastric bypass (GBP) used to be the most preferred surgical method, sleeve gastrectomy (SG) has been gaining popularity in recent years.¹ As such, researchers from the Vestfold Hospital Trust, Tønsberg, Norway, sought to compare the clinical efficacy of these two bariatric procedures in inducing remission of type 2 diabetes (T2D) after surgery.¹

The Oseberg trial was a single-center, two-armed randomized controlled trial that enrolled 109 adult T2D patients with a body mass index (BMI) of ≥35kg/m².¹ The study population was randomized to receive either SG (n=55) or GBP (n=54).¹ Patients who had severe gastroesophageal reflux, drug or alcohol addiction, or previous major abdominal surgery were excluded from the study.¹ After the surgical procedure, patients were followed up at week 5, 16, and 34, then yearly until study completion at 5 years.¹ The primary outcome of the study was remission of T2D 1 year after surgery, defined as having HbA1c level of  ≤6.0% without the use of diabetes medication.¹ Secondary outcomes were assessed 5 years after surgery, which encompassed diabetes remission rates, weight loss and body composition, cardiovascular risk factors, patient-reported outcome measures, and adverse events (AEs).¹

The follow-up period of the Oseberg trial was concluded in December 2022, with roughly 85% of patients in both groups completing the 5-year follow-up.¹ During the follow-up period, 3 patients from the SG group converted to GBP due to insufficient weight loss.¹ The 1-year T2D remission rates of the GBP were significantly higher than that of the SG group (RR=1.57; 95% CI: 1.14-2.16; p=0.0054), which was sustained 5 years after surgery, resulting in a 24% difference in 5-year remission rate between the two groups (p=0.032).¹ Furthermore, the GBP group also exhibited significantly higher remission rates under the new consensus definition of diabetes remission (HbA1c <6.5%) (p=0.018).¹ The statistical significance of the 5-year remission rates was retained after the exclusion of the 3 patients who switched their treatment (p=0.007 for HbA1c ≤6.0%, p=0.003 for HbA1c <6.5%).¹ While both groups exhibited similar reductions in HbA1c levels from baseline (GBP group= -1.7%; SG group= -1.6%), the GBP group had a significantly higher proportion of patients requiring no antidiabetic medication after 5 years (60% vs. 40%, p=0.001).¹  Additionally, significant improvements in weight loss (p<0.001), low-density lipoprotein (LDL) levels (p=0.008), and diastolic blood pressure (BP) (p=0.047) were also observed in the GBP group.¹

In terms of health-related quality of life (HRQoL), both treatment groups exhibited numerical improvements in their scores from the 36-item short-form survey (SF-36),  whereas the scoring from the Impact of Weight on Quality of Life-Lite (IWQOL-Lite) form indicated significant improvements in obesity-specific QoL for the GBP group (p=0.049), mainly driven by the increase in the “self-esteem” category (p=0.014).¹

In terms of safety, the two surgical procedures had comparable safety profiles.¹ The proportion of patients who experienced ≥1 complication event during the 5 years of follow-up was slightly higher in the GBP group (74%) compared to the SG  group (67%), with the most common AEs being infectious, gastroenterological, and musculoskeletal complications.¹ However, 15 patients in the GBP group experienced ≥1 postprandial hypoglycemia event, while only 2 patients in the sleeve gastrectomy group experienced such events (p=0.005).¹

In summary, the Oseberg trial demonstrated GBP’s exceptional efficacy in facilitating T2D remission, enhancing weight loss, reducing cardiovascular risks, and improving obesity-specific QoL of patients.¹ The safety profile of GBP was also similar to that of SG, with an elevated risk of postprandial hypoglycemia.¹ Thus, it was recommended that these findings should serve as clinical evidence in favor of GBP in international diabetes guidelines.¹