Treating Type 2 Diabetes with Gastric Bypass

Is Gastric Bypass Surgery a Silver Bullet in Treating Type 2 Diabetes?

July 15, 2020

Treating Type 2 Diabetes

Obesity is a worldwide problem, affecting over 500 million individuals. More than 1/3 of the United States population suffers from obesity. Along with diet and exercise, weight loss (bariatric) surgery has proven to be the best and most durable method to drop excess pounds.

Average numbers indicate an expected weight loss of 25-30% which is maintained several years after surgery¹. This type of significant weight loss results in an improvement in medical conditions which are typically associated with obesity, as well as improved survival.

This article will summarize the research we have collected throughout the years on the effect of bariatric surgery on one such medical condition, namely, type 2 diabetes mellitus.


The Surgical Treatment and Medications Potentially Eradicate Diabetes Efficiently (STAMPEDE) trial was published by the New England Journal of Medicine in 2017. It demonstrated that in 1 and 3 years of follow-up, patients that underwent bariatric surgery (roux-en-y gastric bypass or sleeve gastrectomy) had superior health outcomes compared to those that underwent intensive medical therapy alone for the treatment of obesity.

Results were seen with relation to improved glycemic control (as measured by a hemoglobin a1c <6%), reduced cardiovascular risk, improved quality of life, and decreased use of diabetic medication. A supplemental study demonstrated results at 5 years of follow-up and showed similar results.

Diabetes remission was also greater in the surgical group compared to the intensive medical therapy group. Similarly, hemoglobin a1c, BMI, and use of glucose-lowering medications were more favorable in the surgical group compared to the medical therapy group².

These studies are excellent examples of short- and intermediate-term follow-up assessing the durability of bariatric surgery and its effect on diabetes mellitus.

What long-term data is available? Another study which was published in 2017 from the New England Journal of Medicine, attempted to answer this question. This article summarized the long-term health benefits of bariatric surgery, focusing on its impact on diabetes.

This was a large-scale observational study that followed patients over the course of 12 years. More than 1,100 morbidly obese patients were divided into one of three groups.

  • Group 1 underwent roux-en-y gastric bypass surgery,
  • Group 2 sought surgery but did not have surgery due to health insurance limitations, and,
  • Group 3 did not seek surgery. Follow-up clinical evaluation was performed at 2 years, 6 years, and 12 years after the study began.

Diabetes was defined as one of the following: elevated fasting blood sugar, hemoglobin a1c>6.5%, or current use of anti-diabetic medication. Remission of the disease was made when none of these criteria were present at the time of follow-up.

The study ran from 2000 to 2016. Data from 90% of patients were available for analysis. Follow-up clinical information was obtained from a combination of patient examination, electronic medical records, telephone interviews and data from primary care providers.

Several informative results were obtained. First, significant differences in weight loss were observed between the three groups. In the surgical group (Group 1), the average loss of body weight was 45 kg at 2 years, 36 kg at 6 years, and 35 kg at 12 years. At 12 years of follow-up, 40% of all surgical patients maintained at least a 30% weight loss from baseline.

Non-surgical patients (Groups 2 and 3) had no significant changes when comparing baseline results to those at year 12 in either weight, body mass index or waist circumference.

Surgical and Non-Surgical Type 2 Diabetes Results

Second, diabetes was cured more frequently in the surgical group compared to the non-surgical groups. At 12 years follow-up, the incidence of diabetes was 3% in the surgical group compared to 26% in each of the non-surgical groups. Of the patients with a diagnosis of diabetes at the beginning of the study, 51% had diabetes remission 12 years after surgery.

The odds of having diabetes was significantly higher in the non-surgical groups compared to the surgical group.

They also found that successful remission of diabetes at 12 years was strongly predicted by baseline medication status. This means that those who were diagnosed with diabetes but were not yet on medication for diabetes at the start of the study, were more likely to have remission of diabetes than those who were on oral medication for diabetes at the same time.

More so, those on oral medication were more likely to have diabetes remission compared to those who were on insulin therapy for diabetes at the study start. For those patients who had diabetes both at baseline and at the 12 year follow-up, improvement was still evident, as the average number of anti-diabetic medications was reduced. This is in comparison to the non-surgical groups who had a significantly higher average number of antidiabetic medications at 12 years.

This study provided some long-term data on medical conditions other than diabetes as well. In concordance with diabetes data, the incidences of both high blood pressure and high cholesterol were significantly lower in the surgical group compared to the non surgical groups. Remission rate of high blood pressure was higher in the surgical group compared to group 1. Also, the remission rate of high cholesterol was significantly higher in the surgical group compared to both non-surgical groups.

Bariatric Surgery Can Cure Type 2 Diabetes For Some Patients

Previous evidence supported bariatric surgery over other methods of weight loss in improving overall health and, specifically, diabetes.  Now we have long-term data showing that roux-en-y gastric bypass offers long-term durability of weight loss and is associated with fewer medical conditions than those who do not undergo weight loss surgery. Specifically, its effect on diabetes is outstanding. We demonstrate a lower incidence of diabetes in those that undergo bariatric surgery. Furthermore, bariatric surgery can cure diabetes in a large percentage of patients. These health changes are long-lasting and translate to improved survival in this patient population.


  1. Weight and Metabolic Outcomes 12 years After Gastric Bypass. Adams TD, Davidson LE, Litwin SE, Kim J, et al. N Engl J Med. 2017 Sept 21; 377(12):1143-1155.
  2. Bariatric Surgery versus Intensive Medical Therapy for Diabetes—5-Year Outcomes. Schauer PR, Bhatt DL, Kirwan JP, Wolski K, et al. N Eng J Med. 2017; 376:641-651.


Dena Arumugam, MD, is a board-certified general surgeon who specializes in minimally invasive surgery, general surgery and bariatric surgery. She earned her medical degree at the Albert Einstein College of Medicine and completed a general surgery residency at Rutgers Robert Wood Johnson Medical School. She refined her laparoscopic surgery skills at New York University Winthrop Hospital with fellowship training in advanced gastrointestinal and bariatric surgery, before returning to New Jersey to practice at Jersey Shore Advanced Surgical Associates.