Weight Loss Surgery Treats Diabetes

Obese type 2 diabetes patients benefit from bariatric surgery

March 29, 2012 / Author:  / Reviewed by: Joseph V. Madia, MD

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Being overweight puts you at risk for a variety of health problems, including type 2 diabetes. It can also lead to high blood pressure, heart disease, and stroke. Fortunately, losing weight can protect you from these serious health problems.

Obesity is the leading cause of type 2 diabetes worldwide. If you already have type 2 diabetes, being overweight or obese can increase your risk of complications.

For most people, a healthy diet and exercise is all it takes to lose weight and prevent the risks associated with diabetes. For some people, though, diet and exercise is not enough. That is where weight loss surgery comes into the picture.

Weight loss surgery, or bariatric surgery, is not for everyone. However, if other weight-loss methods failed you, your doctor may recommend bariatric surgery. It may be your last option for shedding those pounds.

Obesity and Diabetes

How obesity leads to type 2 diabetes

In recent decades, the number of obese Americans has risen dramatically. At the same time, type 2 diabetes has grown to epidemic proportions.

It is no coincidence that these two conditions have grown at similar rates. Obesity is directly linked to type 2 diabetes.

In healthy people, the body breaks down food into sugar that cells throughout the body can use for energy. In order to get the sugar into the cells so they can use it, these cells use a hormone called insulin.

In people with type 2 diabetes, the body's cells do not use insulin properly. Body fat may play a role in these cells' response to insulin.

Scientists believe that fat tissue makes people less sensitive to insulin. That is, as a person gains more fat tissue, he or she will progressively become less sensitive to insulin.

Fat cells release a certain protein that leads to type 2 diabetes. This protein is likely responsible for the reduced sensitivity to insulin. As the body become less sensitive to insulin, the pancreas, which is responsible for insulin production, can become overworked. Eventually, the pancreas may stop making insulin, leading to the development of type 2 diabetes.

Abdominal fat (fat around the waist area) in particular has been linked to type 2 diabetes.

Losing weight

Losing weight, even just a few pounds, can help prevent type 2 diabetes. If you already have diabetes, weight loss is a key part of managing your disease.

Shedding pounds can not only improve your blood sugar levels, it can also reduce your risk of other diabetes-related complications such as heart disease and kidney disease.

In most cases, diabetes patients are told to eat a healthy diet and to get exercise. When this fails, a doctor may recommend surgery.

What is Bariatric Surgery?

Bariatric surgery is a kind of worst-case-scenario treatment for obesity and type 2 diabetes. It is only for obese patients who cannot lose weight through conventional methods.

There are several main types of bariatric surgery. These include:

  • Roux-en-Y gastric bypass
  • Biliopancreatic diversion with duodenal switch
  • Laparoscopic gastric banding
  • Sleeve gastrectomy

Roux-en-Y gastric bypass is a very common weight loss surgery in which the patient's stomach size is reduced. The surgeon makes a new stomach pouch out of a small portion of the original stomach. The new, smaller stomach is attached directly to the small intestine. Not only is the new stomach too small to hold large amounts of food, but the new digestive pathway makes it harder for the body to absorb large amounts of fat.

Biliopancreatic diversion with duodenal switch is similar to the Roux-en-Y surgery, except much of the stomach function is left intact. Instead, the digestive process skips over much of the intestine.

Laparoscopic gastric banding involves placing an inflatable band around the upper section of the stomach. The band limits the amount of food that can enter the stomach. The band can be adjusted in order to meet each patient's needs at any point in time. The band can also be removed.

Sleeve gastrectomy is a surgery in which the left side of the side is removed. This limits the amount of food that can fit in the stomach.

While these surgeries differ in many aspects, the end result is similar: patients can no longer eat or digest as much food as they could before surgery.

Bariatric Surgery as Treatment for Type 2 Diabetes: Recent Research

Although the link between obesity and type 2 diabetes is fairly clear, researchers are still studying weight-loss surgery as a treatment for obese patients with diabetes.

In two recent studies, researchers found that weight loss surgery work better than traditional treatments for obese patients with type 2 diabetes.

High blood sugar levels are a defining characteristic of type 2 diabetes.

In one study, Cleveland Clinic researchers found that some overweight patients who underwent weight loss surgery were able to reach normal blood sugar levels without using any diabetes drugs. Other patients no longer needed insulin to control blood sugar levels after they went through weight loss surgery.

According to lead researcher Philip Schauer, M.D., Director of the Cleveland Clinic Bariatric and Metabolic Institute, "After one year, patients who underwent gastric bypass or sleeve gastrectomy lost more weight and were significantly more successful at controlling their diabetes, compared to those who simply took medications."

For their study, Dr. Schauer and colleagues divided 150 obese diabetes patients into three treatment groups. The first group received only drug treatment for their diabetes. The second group received drug treatment and underwent gastric bypass surgery. The third group received drug treatment and underwent sleeve gastrectomy.

The American Diabetes Association recommends an HbA1c level (a measure of blood sugar over three months) of less than seven percent. For the purpose of this study, the researchers were trying to get patients down to an HbA1c level of six percent or less.

After 12 months, 42.6 percent of the gastric bypass patients and 36.7 of the sleeve gastrectomy patients achieved HbA1c levels of less than six percent. In comparison, only 12.2 percent of the drug treatment group achieved these blood sugar levels.

Dr. Schauer and colleagues believe their findings show that weight loss surgery could be a valuable method for controlling diabetes in those patients who do not respond to drug treatment.

"This trial demonstrates that bariatric surgery can eliminate the need for diabetes medications in many obese patients whose diabetes is poorly controlled," says Dr. Schauer.

"Furthermore, the surgical patients showed major improvements in other measures of heart health, including reduced need for high blood pressure and cholesterol medications, while significantly boosting HDL - the so-called 'good' - cholesterol," he adds.

The results of this Cleveland Clinic study are published in the New England Journal of Medicine and were presented at the Annual Scientific Sessions of the American College of Cardiology in Chicago.

Another study - which is published in an advanced online edition of the New England Journal of Medicine - found similar results to those of the Cleveland Clinic researchers.

In this study, the majority of patients who underwent weight loss surgery were able to stop taking their diabetes medications. They were able to keep their diabetes in remission for at least as long as the two-year study period.

In contrast, none of the patients who received standard drug treatment were able to put the disease in remission.

According to the study's senior author Dr. Francesco Rubino, Chief of Gastrointestinal Metabolic Surgery at New York Presbyterian Hospital and associate professor of surgery at Weill Cornell Medical College, "Although bariatric surgery was initially conceived as a treatment for weight loss, it is now clear that surgery is an excellent approach for the treatment of diabetes and metabolic diseases."

The study by Dr. Rubino and colleagues involved 60 severely obese patients with type 2 diabetes. These patients were assigned to one of three treatment groups: Roux-en-Y gastric bypass surgery, biliopancreatic diversion, or conventional drug treatment.

None of the patients in the drug treatment group reached remission.

In comparison, 95 percent of patients who underwent biliopancreatic diversion and 75 percent of those who underwent Roux-en-Y gastric bypass achieved remission.

In addition to finding that weight loss surgery improves blood sugar levels, the researchers found that surgery can also reduce levels of 'bad' cholesterol while improving levels of 'good' cholesterol.

"The unique ability of surgery to improve blood sugar levels and cholesterol levels as well as reduce weight makes it an ideal approach for obese patients with type 2 diabetes," says Dr. Geltrude Mingrone, professor of Medicine at Catholic University in Rome and lead author of the study.

"These findings confirm that the effects of bariatric surgery on type 2 diabetes may be attributed to the mechanisms of surgery rather than the consequences of weight loss," Dr. Mingrone explains. In other words, type 2 diabetes patients may be benefiting from the surgery itself rather than the weight loss.

While Dr. Mingrone is talking about her own team's findings, her comments can apply to both of these recent studies. More research is needed to understand how weight loss surgery is leading to such immediate effects on type 2 diabetes.