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Gastric Bypass and Diabetes: Is it a cure?

Gastric Bypass and Diabetes: Is it a cure?

Beyond helping with weight loss, gastric bypass surgery can have a dramatic effect in treating type 2 diabetes. Research suggests that the vast majority of people who undergo a gastric bypass procedure achieve complete remission of their type 2 diabetes.

What is gastric bypass surgery?

Gastric bypass, also known as a Roux-en-Y, is a procedure that permanently alters how your body digests food. The stomach is reduced to a small pouch and is connected to a lower part of the small intestine. Gastric bypass surgery helps with weight loss in two main ways:

  1. Restricting food intake. With the stomach about the size of a walnut, you feel full with very little food.
  2. Malabsorption. Because food passes through the small intestine much quicker, less of it is absorbed.

Those who undergo gastric bypass surgery can expect to lose 60-80% of their excess weight.

How does gastric bypass surgery relate to diabetes?

At its core, diabetes is a problem with how your body manages blood sugar. Normally, when food is broken down into sugar, the hormone insulin is used to carry this sugar out of the blood and into body cells where it is used for energy. In diabetes, this system breaks down and insulin can no longer properly do its job. This leads to elevated blood sugar, which over time, can lead to damage to body organs.

Diabetes is classified into two main types:

Type 1 diabetes is when the body cannot make any insulin, and thus lifelong insulin medication is required for survival. Type 1 typically affects younger people and is rarer.

Type 2 diabetes is the more common type of diabetes. Although the body still makes insulin, the body is not able to use it well.

Type 2 diabetes is a common complication of carrying excess weight

Extra weight can cause insulin resistance, which is when insulin is produced but no longer recognized by the body. In an insulin-resistant state, sugar is not able to be moved out of the blood as efficiently. To compensate, the body makes more and more insulin until it burns out and cannot produce enough.

Over time, these two issues can cause blood sugar to rise to dangerous levels. When blood sugar remains uncontrolled, it can damage the eyes, kidneys, blood vessels, nerves, and the heart.

Reduced blood flow is a complication of diabetes that can lead to slowed wound healing.

Traditionally, type 2 diabetes is treated through a combination of lifestyle changes and medication. Losing weight, eating right, and exercising can improve blood sugars, although usually to a modest degree. Medications such as oral pills and insulin are usually needed on top of lifestyle changes to maintain diabetes control.

Because type 2 diabetes is difficult to control and is a lifelong condition, many people seek treatments that can lead to lasting improvements in blood sugar, such as gastric bypass surgery.

How does gastric bypass surgery affect diabetes?

Gastric bypass surgery can result in rapid improvements to blood sugar and lead to complete diabetes remission, but why does this happen?

Weight loss is a clear component, but blood sugar can improve quickly after surgery, even before much weight is lost. Scientists are still working to figure this out, but there are a number of suspected causes:

  • Improved sensitivity to insulin.
  • Reduced carbohydrate intake.
  • Changes in blood sugar hormones.
  • Changes in hunger and fullness hormones.
  • Changes in gut bacteria.
Losing weight is not the only reason diabetes improves after gastric bypass surgery.

Essentially, it is thought that after surgery there is a sharp drop in food consumed. Food that is consumed hits the small intestine quicker, and body hormones are able to respond better to balance blood sugar. As more weight is lost, the body is no longer resistant to insulin which further helps blood sugars stay controlled.

Does gastric bypass surgery cure diabetes?

Gastric bypass surgery is often thought to be a cure for type 2 diabetes. It’s true that this surgery can cause blood sugars to return completely to normal, and stay there without the use of medications. For all intents and purposes, this can feel like a cure; however, most experts refer to this as “diabetes remission.”

The term diabetes remission is more accurate because, although unlikely, it is possible for diabetes to return. If weight regain occurs, insulin resistance can occur with it, and lead to a recurrence of diabetes. In addition, a small percentage of people can experience a recurrence of diabetes for unknown reasons. Finally, although most do achieve complete diabetes remission, some who undergo the surgery achieve only an improvement in their diabetes.

What about type 1 diabetes?

Type 1 diabetes is classified as an auto-immune condition, where the body attacks its own organs, leading to complete destruction of insulin production. Type 1 diabetes is not related to weight and most with this type of diabetes are of normal weight.

Thus, it is uncommon for those with type 1 diabetes to pursue gastric bypass surgery. Still, people with type 1 diabetes who are severely overweight can experience benefit to their diabetes if they get surgery. This area is not studied well, but some studies suggest that the amount of insulin required drops drastically after surgery. Even though this can improve blood sugars and quality of life, type 1 diabetes cannot be cured through gastric bypass surgery.

Avoiding low blood sugars

Most diabetes medications will need to be reduced or stopped after surgery.

Since blood sugar can return to normal quickly after surgery, it is important to work with your medical provider to safely reduce diabetes medications.

Diabetes medications may no longer be necessary and can cause a dangerous drop in blood sugar known as hypoglycemia. Certain diabetes medications, including a class of pills known as sulfonylureas as well as insulin injections are most likely to cause hypoglycemia. These medications work by increasing available insulin in the body to bring down blood sugar; however, if blood sugar is already low, then sugar will continue to drop to below normal levels. Additional testing of blood sugar during the initial period after surgery is important to avoid these issues.

Testing blood sugar is important to avoid hypoglycemia.

To summarize, gastric bypass surgery can create diabetes remission

Type 2 diabetes is a complication of obesity and is often a reason to pursue gastric bypass surgery. Gastric bypass surgery leads to complete and sustained diabetes remission in a majority of cases. It accomplishes this through a variety of complex means that involve helping the body to use its own insulin.

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Michael Fornaris, RD, CDE


Michael is a registered dietitian & diabetes educator currently working in outpatient nutrition counseling. He specializes in weight management, diabetes control, prediabetes, and metabolic syndrome.

Gintas Antanavicius, MD, FACS, FASMBS

Medical Reviewer

Dr. G is a co-founder of BariBuilder. A US-based expert surgeon with over 10 years of bariatric experience, he regularly publishes research in medical journals like SOARD, Obesity Surgery, etc.