Bariatric Surgery for People with Type 2 Diabetes and Prediabetes

Q&A with Ozanan Meireles, MD

Q: What is type 2 diabetes? What is prediabetes?

Type 2 diabetes is a chronic, degenerative disease that develops when the body cannot make enough, or properly use, insulin – a hormone that helps regulate sugar (glucose) in the body. Prediabetes is a precursor to type 2 diabetes, defined by above-average glucose levels.

Q: Do bariatric surgeries (Roux-en-Y gastric bypass, adjustable gastric banding and vertical sleeve gastrectomy) cure type 2 diabetes?

A: Patients are often told weight loss surgeries will cure diabetes. That’s simply not true. However, individuals with type 2 diabetes or prediabetes and obesity may benefit from the modest weight loss achieved through surgery.

After a gastric bypass or a sleeve gastrectomy, patients experience weight loss and changes in their gastrointestinal tract. Weight loss surgery causes profound changes in the incretins — hormones in the gastrointestinal tract that cause insulin to be released. These changes lead to significant improvement in type 2 diabetes and can cause long-term changes in the pancreas that causes diabetes to go away.

These changes may help individuals:

  • Achieve remission for type 2 diabetes
  • Decrease the amount of medications they need on a daily basis
  • Postpone the onset of diabetes (for individuals with prediabetes)

Q: How can weight loss surgery affect diabetes treatment?

A: Modest weight loss can postpone the onset of diabetes for people with prediabetes. If diabetes is in the early stages, the individual might be able to stop taking diabetes medications (such as metfromin or insulin) for many years. For people with longstanding diabetes, taking oral medications, the effects of surgery may allow sugar levels to be controlled with food restrictions only. If the diabetes has been present for more than 10 years and progressed enough that the individual needs insulin injections, weight loss procedures may allow him/her to switch to oral medications.

Q: Is one procedure better than another to reverse or slow the onset of diabetes?

A: The New England Journal of Medicine recently published articles (see below) that showed an improvement in patients with type 2 diabetes after either the vertical sleeve gastrectomy or the gastric bypass.

There is much more literature on diabetes improvement, control and resolution with the gastric bypass than the sleeve gastrectomy. Some new studies that address the benefits of sleeve gastrectomy are being published, but to date a long-term study comparing the two procedures has not been done.  

The adjustable gastric band can have an effect on type 2 diabetes by promoting weight loss, but it does not offer the same incretin effect as the other two weight loss procedures.

Q: Are these procedures worth doing to minimize the effects of type 2 diabetes?

A: All severely obese patients can benefit from bariatric surgery, either by achieving remission, by decreasing the amount of medications they take on a daily basis or by postponing the onset of diabetes in their lifetime.

Q: How long will the positive effects of surgery last?

A: We don’t know for sure how long the body will increase insulin production after weight loss surgery. But even the ability to go a 10-year period with increased glycemic (blood sugar) control is a major advantage to long-term health.

Q: How do doctors at Massachusetts General Hospital determine if bariatric surgery is the right choice for patients?

Patients of the Massachusetts General Hospital Weight Center receive a multidisciplinary evaluation by a physician specializing in obesity medicine, a dietitian and a psychologist specializing in obesity. The patient’s care team will then develop a personalized care plan that may include involvement in the Medical Management Program and/or Bariatric and Metabolic Surgery Program at Mass General.

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