October 2, 2023

Many individuals with type 2 diabetes who have gastric bypass see results even before leaving the hospital.

Traditionally, type 2 diabetes has been treated with medications, nutritional changes and encouragement to lose weight through diet and exercise. But a growing body of research with real-life results has shown that bariatric surgery, also called weight loss surgery, can put type 2 diabetes into remission, help patients get off their medications and improve quality of life. Some of these benefits even occur before significant weight loss is achieved.

“In the past, we’ve thought about weight loss surgery as just that — a surgery for helping people fight the disease of obesity,” said Dr. Matthew Spann, a bariatric surgeon and medical director of the Vanderbilt Surgical Weight Loss Center. “What we know now is that there are a lot of other factors besides just weight that are impacted by bariatric surgery. One such factor is an almost immediate and weight-independent improvement of type 2 diabetes.”

We asked Spann to explain how weight loss surgery can be life-changing for patients with type 2 diabetes.

What are the research basics?

A study published in the New England Journal of Medicine analyzed the five-year outcomes of 150 patients undergoing type 2 diabetes treatment. In a randomized trial, patients either underwent weight loss surgery and medical treatment or just medical treatment for the disease.

“Out of this randomized trial, we saw that the impact bariatric surgery had on diabetes was far greater than what we could achieve with just medication alone,” Spann explained.

At the five-year follow-up point, about 89 percent of the patients in the surgical groups were not taking insulin, and they maintained an average glycated hemoglobin level (HbA1c) under 7 percent. The blood HbA1c level is a measurement of how well diabetes is controlled, with the normal range considered to be less than 6 percent. Of the patients who only received medical treatment for their diabetes, only 61 percent were not taking insulin at the five-year mark, and they had an average HbA1c level of 8.5 percent.

Can weight loss surgery really help patients get off or reduce medications?

Spann has seen incredible and immediate results with his own patients. “After leaving the hospital, they will stop oral medications, and we have a good deal of success with that being the case for five years and beyond after surgery,” he said.

The physical health benefits of patients achieving type 2 diabetes remission are significant, but Spann sees another important gain that’s hard to quantify in a study. “If you can have someone not have to check their blood sugars four times a day and not have to give themselves insulin injections multiple times a day, the benefit from a quality of life standpoint is immeasurable.”

How do weight loss surgeries affect type 2 diabetes?

When it comes to weight loss surgery for diabetes reversal, there are two main options: a sleeve gastrectomy or a Roux-en-Y gastric bypass. With a sleeve gastrectomy, about 85 percent of the stomach is removed. In a Roux-en-Y gastric bypass, the size of the stomach that gets exposed to food is reduced, and then the first portion of the small intestine is bypassed. Both procedures help patients feel full faster than before surgery. In addition, gastric bypass inhibits some calorie absorption. Both surgeries also deliver food to the large intestine at a faster rate, resulting in a beneficial hormonal impact, Spann said.

Researchers theorize that the physiological changes associated with weight loss surgery help patients with type 2 diabetes improve glucose homeostasis, according to an article published in the Journal of Clinical Endocrinology & Metabolism.

Who should consider weight loss surgery?

Spann recommends bariatric surgery for patients with type 2 diabetes who also battle obesity. “Certainly, the safest way for weight loss is with the least invasive means necessary,” he explained. “However, a lot of patients whom we see have already tried diet and exercise multiple times.”

Plus, time may be a critical factor for some. “We are running the risk that diabetes has on our body systems,” Spann said. “That’s called end-organ damage.” Opting for weight loss surgery can help prevent diabetes-related injury to the kidneys, heart and nerves, for example.

Typically, individuals with a body mass index (BMI) of 35 or higher are considered possible candidates for weight loss surgery. (This is the recommendation from the American Society for Metabolic and Bariatric Surgery. In 2022, that group changed its recommendation about BMI, lowering it from 40.) However, patients who are struggling with both obesity and type 2 diabetes who have a BMI lower than 35 may also be candidates.

“What we’ve learned from multiple randomized controlled trials involving weight loss surgery in patients with diabetes is that patients would likely benefit from surgery starting at a BMI of just 30,” Spann said.

Whether a procedure is right for you will depend on additional individual health factors. Risks associated with bariatric surgery are similar to other abdominal surgeries performed in a minimally invasive fashion, Spann said. Talk to your health care provider for a complete list of considerations.

weight loss plateau

Advanced care for weight loss

The Vanderbilt Surgical Weight Loss program offers advanced care to help you lose weight and improve your overall health. If you’ve been unable to reach a healthy weight with nutritional and lifestyle improvements alone, surgery might be a better and safer option for achieving your weight loss goals. This team will work with you to develop a personalized care plan combining surgery, nutrition, exercise and psychological support.


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