Gastric Bypass Boasts Greater Benefit for Diabetics Than Sleeve Gastrectomy

Kathleen McTigue, MD, MPH

A new study is shedding light on the differences in long-term diabetes outcomes among patients undergoing the 2 most popular types of weight loss surgeries, including rates of diabetic remission and improvements in glycemic control.

Results of the study, which examined nearly 10,000 patients who underwent a sleeve gastrectomy (SG) and gastric bypass as part of the PCORnet Bariatric Study, indicated patients who underwent Roux-en-Y gastric bypass (RYGB) had greater weight loss, higher type 2 diabetes (T2D) remission rate, fewer relapse events, and improved long-term glycemic control compared to their counterparts who underwent SG.

With multiple studies demonstrating the beneficial effects of bariatric surgery in T2D patients, investigators from the University of Pittsburgh—led by Kathleen Mctigue, MD—conducted a cohort study of patients from 34 PCORnet-affiliated health systems from January 2005 through September 2015. A total of 9710 patients were identified for inclusion, all of which had an HbA1c level of 6.5% or more or a prescription for a diabetes medication in the year prior to surgery—patients were excluded if they were over the age of 80 or lacked relevant outcomes data.

Using Cox proportional hazards models, investigators sought to determine how outcomes—specifically, T2D remission rates, T2DM relapse, percentage of total weight lost, and change in HbA1c—differed between patients undergoing the 2 procedures. Remission was defined as the first occurrence of HbA1c level under 6.5% following 6 months without a T2D prescription order and relapse was the occurrence of levels of 6.5% or more and/or a prescription for T2D medication after remission.

The study cohort had a mean follow-up time of 2.7 (2.9) years, mean age of 49.8 years, and a mean BMI of 49.0—investigators also noted 7051 of the 9710 (72.6%) were female and 6040 (72.2%) were white. Of note, 6233 patients underwent RYGB and 3477 underwent SG.

Results of the analyses revealed patients who underwent RYGB experienced significantly greater weight loss at 1 year (mean difference, 6.3 [95% CI, 5.8-6.7] percentage points) and 5 years (mean difference, 8.1 [95% CI, 6.6-9.6] percentage points) when compared to patients who underwent SG. Analysis of HbA1c indicated greater benefit from RYGB versus SG with RYGB patients experiencing a reduction of 0.45 (95% CI, 0.27-0.63) percentage points more than those who underwent SG.

A total of 6141 patients experienced T2D remission during the follow-up. Remission rates were approximately 10% higher in RYGB patients (HR 1.10, 95% CI, 1.04-1.16) and adjusted cumulative remission rates for RYGB patients was 59.2% (95% CI, 57.7%-60.7%) compared to 55.9% in the SG cohort at 1 year. This effect was still present at 5 years with remission rates of 86.1% (95% CI, 84.7%-87.3%) among RYGB patients and 83.5% (95% CI, 81.6%-85.1%) among the SG cohort.

When examining relapse rates, results indicated a lower rate among those who had RYGB than those who underwent SG (HR 0.75, 95% CI, 0.67-0.84). Furthermore, estimated relapse rates for RYGB and SG were 8.4% (95% CI, 7.4%-9.3%) and 11.0% (95% CI, 9.6%-12.4%) at 1 year and 33.1% (95% CI, 29.6%-36.5%) and 41.6% (95% CI, 36.8%-46.1%) at 5 years after surgery, respectively.

In an invited commentary, Natalie Liu, MD, general surgery resident, and Luke Funk, MD, MPH, associate professor, both of the University of Wisconsin, commended investigators for the aim and results of their study but pointed out many barriers still exist in real-world application—particularly, those inhibiting patients from receiving such procedures.

“This analysis is an important contribution. It included long-term electronic health record data from a large cohort of US patients who had bariatric surgery in a real-world setting,” the authors wrote. “Although both RYGB and SG were associated with high rates of T2DM remission, a considerable number of patients relapsed, particularly following SG. Given that the drivers of diabetes relapse after bariatric surgery are unclear, further investigation into this phenomenon is needed.”

This study, “Comparing the 5-Year Diabetes Outcomes of Sleeve Gastrectomy and Gastric Bypass,” is published in JAMA Surgery.