Treating Diabetes With Bariatric Surgery

Weight-loss surgery can be an effective option for type 2 diabetes

Heavyset African-American woman with type 2 diabetes rests on track after workout.

Weight-loss surgery can be an effective option for type 2 diabetes

If you are severely overweight and have type 2 diabetes, bariatric surgery is a potential option to treat both conditions.


Bariatric surgery, also known as weight-loss surgery, is considered to be an effective treatment for obese people who are unable to lose weight through diet, exercise, lifestyle changes and weight-loss medications.


“Weight-loss surgery is an effective intervention for people with type 2 diabetes when other therapies for morbid obesity fail,” says William Fuller, MD, a bariatric surgeon at Scripps Clinic. “It's considered when the patient has done everything to lose weight, but cannot achieve significant, sustained weight loss.”

Type 2 diabetes and obesity

Almost 90 percent of people living with type 2 diabetes are overweight or have obesity, according to the Centers for Disease Control and Prevention (CDC). Type 2 diabetes requires treatment to prevent long-term health problems, including cardiovascular disease, stroke, blindness, kidney failure and amputations.


Studies show that people with type 2 diabetes experience rapid improvement in their blood sugar levels after bariatric surgery.

Who's a candidate for bariatric surgery?

Weight-loss surgery is a serious decision and careful patient selection is critical for a successful outcome. Body mass index (BMI), a measure used to evaluate body weight relative to your height, is used to find out if you are underweight, normal weight, overweight or obese.


According to the National Institutes of Health, bariatric surgery may be an option for adults who have:

  • A BMI of 40 or more 
  • A BMI between 35 and 39.9 and a serious obesity-related health problem, such as type 2 diabetes, heart disease or severe sleep apnea

Can bariatric surgery cure type 2 diabetes?

Bariatric surgery causes weight loss by reducing the size of the stomach and limiting the amount of food it can hold. The procedure can also cause hormonal changes that help reduce hunger and increase the feeling of fullness. Blood glucose levels can also change.


“Blood glucose levels start to improve after surgery, even before large amounts of weight loss,” Dr. Fuller says. “As a result, many patients are able to scale back on diabetic medications and go into remission.”


Dr. Fuller speaks from experience. He has performed more than 2,000 bariatric surgeries, with an emphasis on minimally invasive procedures. About 30 to 40 percent of his patients have diabetes, he says.

Types of bariatric surgery

The most common weight-loss procedures are gastric bypass and sleeve gastrectomy (also known as gastric sleeve). Gastric sleeve and gastric bypass are considered safe and highly effective for treating type 2 diabetes.

Gastric bypass surgery (Roux-en-Y gastric bypass)

In gastric bypass, the surgeon reduces the size of the stomach by creating a small pouch on top of the stomach. While the average human stomach can hold up to two quarts, this new stomach pouch has a capacity of roughly two ounces. This means you feel full after eating just a small amount of food.


Studies show the surgery causes remission of type 2 diabetes in 80 percent of patients. This improvement is partly explained by changes in hormones produced by the gut after the surgery.


“This weight-loss surgery appears to set in motion certain chemical changes in the patient’s body that help set up better control of blood sugar levels,” Dr. Fuller says. “After the procedure, gut hormones involved in appetite and weight reduction are altered.”

Gastric sleeve

In this procedure, the surgeon removes 80 percent of the stomach. The remaining portion, which is shaped like a sleeve, holds less food. Gastric sleeve also causes some changes in gut hormones. Diabetes remission rates are also very high, more than 60 percent, according to studies.

Is bariatric surgery safe?

While bariatric surgery is safe, there are still risks. Surgery for patients with type 2 diabetes must include ongoing multidisciplinary care, patient education and follow-up, as well as safe and effective surgical procedures. “It’s still surgery and all risks and expectations should be discussed,” Dr. Fuller says.


“It's worth repeating that this kind of surgery is considered only when other efforts have failed and the patient is at risk for other serious conditions. In those cases, the risks posed by the surgery are greatly outweighed by the risks of being obese,” he says.


Minimally invasive surgical techniques are typically used in weight-loss surgery, meaning only a few small incisions are made during the procedure. As such, wound healing does not become a difficult challenge for bariatric patients with diabetes. “Perhaps the biggest concern is adjusting medication requirements after the procedure to account for the body’s changing needs,” Dr. Fuller says.

Life after surgery

Lifestyle changes after surgery are extremely important, Dr. Fuller says. “Patients must be willing to make considerable changes to achieve long-term success.”


This includes maintaining a healthy body weight and reducing other risk factors by eating more whole foods, avoiding refined and processed foods and increasing physical activity, he says.

The importance of patient choice

Athena Philis-Tsimikas, MD, an endocrinologist and corporate vice president of the Scripps Whittier Diabetes Institute, says any method that significantly reduces caloric intake can yield positive results. She stresses the importance of non-surgical options before surgery is considered.


“It’s important that patients understand how limiting calories is essential to diabetes treatment, and that there is a full spectrum of options to achieve this,” she says.