How Effective Is Gastric Bypass Surgery In Curing Type-2 Diabetes?

An emerging trend in the past fifteen years has been the increasing use of gastric bypass surgery as a treatment for morbid obesity. Recent scientific studies have found that not only does gastric bypass surgery lead to a dramatic amount of weight loss, it also results in the remission of diabetes in as many as 90% of cases, often within just a few weeks of the surgery.

Gastric bypass surgery belongs to a class of operations known as bariatric surgeries which are designed to help morbidly obese individuals lose weight. The gastric bypass procedure is carried out by closing off a small stomach pouch from the rest of the stomach. The intestines are then detached from the stomach and connected directly to the pouch so that the remainder of the stomach is “bypassed”. The treatment reduces the volume of food the stomach can hold leading to a reduction in hunger cravings and a feeling of fullness after only a small amount of food is consumed.

The procedure not only leads to weight loss, but also leads to the remission of type-2 diabetes in the overwhelming majority of patients. One study, published in the New England Journal of Medicine in December, 2004, compared the health outcomes of 2,000 obese individuals who underwent gastric bypass surgery with 2,000 control subjects who did not undergo surgery.

The researchers found that the incidence of type-2 diabetes was over seven times lower in the surgery group compared to the control group two years after the surgery and four times lower in the surgery group ten years after the surgery. Furthermore, 72% of diabetic patients who underwent the surgery no longer had diabetes two years after the surgery however this figure dropped to 36% ten years after the surgery.

Another study, published by the Journal of the American Medical Association in 2004 reviewed the results of 136 previous studies and found that gastric bypass surgery led to complete remission of type-2 diabetes 83.7% of the time and improved or resolved type-2 diabetes in 93.2% of cases.

Finally a report published in the Annals of Surgery found that just 30 out of 288 diabetic patients did not achieve remission following gastric bypass surgery.

It was initially believed that the beneficial effects of gastric bypass surgery on diabetes were due solely to the loss of excess weight however recent evidence has suggested that this is not the case. First, in diabetics who lose weight without surgery, modest improvements in glycemic control are observed but complete remission of type-2 diabetes is quite rare. Second, diabetes remission often occurs just days after surgery, long before significant weight loss has occurred.

Scientists have proposed several possible mechanisms that might further explain the ability of gastric bypass surgery to achieve remission of diabetes.

One explanation is that the dramatic reductions in caloric intake lead to a reduction in glucose levels, an improvement in insulin response, and a remission of type-2 diabetes in many cases. One study, published in the Archives of Internal Medicine looked at the effects of a very low calorie diet of 420 calories a day on six obese, diabetic women. The diet led to a reduction in fasting blood glucose levels from an average of 293mg/dL to 126mg/dL. A second study found that a 300 calorie a day liquid diet reduced fasting blood glucose levels from an average of 291mg/dL to 95mg/dL. An individual is considered to be diabetic if they have a fasting blood glucose level above 125mg/dL.

Although both these studies involved extremely low calorie intakes (average daily calorie intake is around 1600 calories after gastric bypass surgery), it is clear that calorie restriction can lead to a significant reduction in blood sugar levels.

A second possible mechanism is that gastric bypass surgery might interfere with the secretion of some unknown chemical from the upper intestine that is responsible for insulin resistance however to date, no such chemical has been isolated.

Those who undergo gastric bypass surgery need to be aware of the risks of the surgery. The surgery carries a mortality rate of between 0.2 and 1.0% depending on the age and weight of the patient, and the experience of the surgeon. Around 10% of patients have post-operative complications such as hemorrhaging, infection, leakages from the pouch into the stomach, or the development of a hernia.

It is also possible for type-2 diabetes to redevelop in those who had previously achieved remission, however this is rare in those who exercise regularly and follow a healthy eating plan. Remission of diabetes following surgery is less common in the elderly, and those with either severe diabetes or who have had the disease for a long period of time.

Current recommendations for gastric bypass surgery require the patient to have a BMI over 40, or a BMI of over 35 and at least one obesity related medical condition such as type-2 diabetes, hypertension, or sleep apnea.