Long-Term Outcomes of Bariatric Surgery

Bariatric surgery has been proven to be an effective treatment of type 2 diabetes for people with obesity, but long-term outcomes have yet to be determined. 

Surgery to reduce weight has increased in popularity over the past two decades. Previous studies have shown bariatric surgery to be successful in weight loss and remission of diabetes. Treatment of type 2 diabetes can consist of oral and injectable medicines, which vary in side effects and overall efficacy. These conventional treatments only partially achieve adequate glycemic control and a reduction in cardiovascular risk. For people with obesity, managing diabetes can be challenging, and the fact that some drugs can cause weight gain does not help. Diet and exercise are mainstays in the treatment of diabetes. Bariatric surgery, which consists of (Roux-en-Y gastric bypass [RYGB] or laparoscopic adjustable gastric banding [LAGB]), was initially intended only for weight loss but showed significant improvements in type 2 diabetes and reductions in cardiovascular disease and mortality. Questions remain about the long-term side effects and outcomes of bariatric surgery. This study aimed to compare the remission of T2DM following surgical or non-surgical treatments at five years follow up.  

This randomized control trial took place at the University of Pittsburgh from October 2009 to March 2012.  In total, 61 participants with obesity and T2DM were initially randomized to either bariatric surgical treatments or an intensive lifestyle weight loss intervention program for one year. Lower level lifestyle weight-loss interventions were then delivered for four years. Of the 61 participants, 82% were women, and 21% were African American. The inclusion criteria were adults 25 to 55 years old with a BMI of 30 to 40 kg/m2 and a diagnosis of T2DM confirmed by fasting plasma glucose (FPG) level of greater than 125mg/dl and treatment with at least one glucose-lowering medication. Treatment groups were split in a 1:1:1 ratio and assigned to Roux-en-Y gastric bypass, gastric banding, or an intensive lifestyle weight loss intervention program for one year, followed by four years of lower-level lifestyle weight-loss interventions. The primary outcome was diabetes remission at five years. Secondary outcomes included glycemic control and medications, weight change, lipid profile changes, blood pressure, and adverse events.   

This study compared the 5-year remission of diabetes following surgical versus non-surgical treatments and found that surgical therapies were more effective than lifestyle intervention alone. At five years, six (30%) gastric bypass participants achieved at least partial type 2 diabetes remission compared to four (19%) gastric banding participants and none in the intensive lifestyle weight loss intervention group. Declines in remission over time occurred for both surgical groups; from 60% at one year to 40% at three years and 30% at five years for gastric bypass and 29% at 1 and 3 years to 19% at five years for laparoscopic adjustable gastric banding. No one in the intensive lifestyle weight loss intervention group achieved remission at any time.   

At five years, both surgical procedures were superior to lifestyle intervention alone in achieving glycemic control defined by hemoglobin A1c and fasting plasma glucose levels. The gastric bypass group had the largest share of participants (56%) who no longer required any medications compared to those in the gastric banding group (45%) and intensive lifestyle weight loss intervention (0%) groups (p=0.0065). Reductions in body weight, BMI, and waist circumference were most significant in patients treated with gastric bypass, followed by gastric banding and, finally, intensive lifestyle weight loss intervention (p<0.0005). The gastric bypass group demonstrated the most significant improvements in triglyceride levels (p=0.0003) and high-density lipoprotein levels (p=0.0042) compared to the gastric banding group. There were no deaths in any group. Stent placement did occur in the gastric bypass group; two blood pressure–related events occurred in the gastric banding group.   

Gastric bypass showed the highest efficacy for type 2 diabetes remission and other variables for glycemic control. Remission rates did decline over the five years, so more research has to focus on maintaining remission. Surgically treated participants used fewer medications, and nearly half used no medicines. Other studies have found similar results, so the findings of this study can guide decisions on how to treat people who have obesity and diabetes and who are not adequately responding to max doses of standard treatment.   

Practice Pearls:   

• Bariatric surgery is safe and more effective than lifestyle interventions alone for long term diabetes remission and glycemic control.  
• Bariatric surgery should be on the treatment guidelines for people with T2DM and all obesity classes.  
• Future studies should focus on strategies to maintain remission.   

Reference for “Long-Term Outcomes of Bariatric Surgery ”:
Courcoulas, Anita P., et al. “Bariatric Surgery vs. Lifestyle Intervention for Diabetes Treatment: Five Year Outcomes From a Randomized Trial.“ The Journal of Clinical Endocrinology & Metabolism, The Endocrine Society, Jan. 2020, doi:10.1210/clinem/dgaa006.  

Mingrone, Geltrude, et al. “Bariatric Surgery versus Conventional Medical Therapy for Type 2 Diabetes.“ New England Journal of Medicine, vol. 366, no. 17, Massachusetts Medical Society, Apr. 2012, pp. 1577–85, doi:10.1056/NEJMoa1200111.  

Antonio Bess, Pharm D Candidate, Florida A&M University 

See more about the outcomes of bariatric surgery and other surgical treatments for diabetes in our therapy center.