Diabetes Remission In Obese Patients More Likely With Weight Loss Surgery

Gastric banding surgery appeared to be more effective than conventional weight loss and diabetes control at helping obese patients with type 2 diabetes lose weight and achieve remission of diabetes, revealed the results of a preliminary study by researchers in Australia.

The study is published in the January 23rd issue of the Journal of the American Medical Association (JAMA) and is the work of Dr John B Dixon, of Monash University, Melbourne, Australia, and colleagues.

Recent studies have shown that weight loss plays a strong factor in improvement in glucose control in type 2 diabetes, which with obesity will be the greatest public health challenge of the next ten or twenty years, wrote the authors. Increasing rates of obesity are strongly linked to increasing prevalence of diabetes.

Conventional methods of weight loss that rely on drugs and lifestyle changes tend to achieve only modest weight loss, a problem made even more difficult for type 2 diabetics because they have greater difficulty losing weight than people without diabetes.

Some observational studies have suggested that surgically induced ways of losing weight, such as gastric banding, achieve sustained weight loss and may be an effective way to treat type 2 diabetes. Dixon and colleagues decided to investigate this using a randomized controlled trial.

The trial, which took place at the Monash University Obesity Research Center in Australia and involved 60 obese patients, started in December 2002 and finished in December 2006. The patients had been recently diagnosed with type 2 diabetes (within the previous two years). Obesity was defined as having a body mass index (BMI) above 30 and below 40. A person's BMI is their weight in kilos divided by the square of their height in metres.

The patients were randomized to two treatment groups: a surgical group and a conventional therapy group. In the surgical group patients received laparoscopic adjustable gastric banding with conventional diabetes care. In the conventional group patients had conventional diabetes therapy, with a focus on weight loss through changes in lifestyle.

The researchers used glycated hemoglobin (HbA1c) levels to measure blood glucose, monitored the patients' weight loss and measures of metabolic syndrome.

Remission was defined as having a fasting glucose level below 126 mg/dL and value of less than 5.2 per cent, while not receiving glycemic therapy.

The results showed that:

* 55 of the 60 patients completed the two year follow up.

* There were no serious complications among the patients in either group.

* 22 (72 per cent) of the surgical group patients and 4 (13 per cent) of the conventional therapy group achieved remission of type 2 diabetes.

* This represented a remission rate of 76 per cent for the surgery group and 15 per cent for the conventional therapy group.

* The surgical group lost 21 per cent of their weight on average, compared with under 2 per cent in the conventional therapy group after 2 years.

* This translates to an over 60 per cent excess weight loss in the surgical group (based on BMI of 25 as ideal) compared with just over 4 per cent in the conventional therapy group.

* After 2 years follow up, the surgical group displayed a 5 times higher remission rate and 4 times greater reduction in blood glucose (glycated hemoglobin) than the convention therapy group.

* Greater weight loss after 2 years and a lower level of blood glucose at the start of the study were independently linked with remission, but weight loss accounted for most of the variance.

The authors concluded that:

"Participants randomized to surgical therapy were more likely to achieve remission of type 2 diabetes through greater weight loss."

However, they said a larger study in a more diverse population, that takes into account longer term outcomes, is needed to confirm these preliminary results.

The researchers also wrote that these results pointed to the degree of weight loss, and not necessarily the way it was achieved, as the major driver of glycemic improvement and diabetes remission among the obese patients.

The implication of this is that it may be more important to aim for intensive weight loss than simple lifestyle change when treating type 2 diabetes, they wrote.

"This study shows that few participants achieved remission with a body weight loss of less than 10 percent, a level expected to produce important health benefits," added the researchers.

Commenting in an accompanying editorial, Drs David E Cummings and David R Flum, of the University of Washington, Seattle, wrote " ... there is much to learn about surgical treatments for diabetes."

"Researchers are striving to elucidate surgical mechanisms of diabetes improvement, hoping ultimately to harness the effects of 'surgery in a pill'; i.e. a formulation providing the desired effects without operative risks," they added.

They suggested the future looks "brighter" for patients and that the results coming out of studies of surgical ways of treating diabetes may be "the most profound since the discovery of insulin".

In the face of an expanding epidemic, "policy and health care leaders are grappling with the costs and risks of surgical interventions, which must be balanced against the costs and risks of not taking advantage of surgically induced diabetes remission", they wrote.

"Adjustable Gastric Banding and Conventional Therapy for Type 2 Diabetes: A Randomized Controlled Trial."
John B. Dixon; Paul E. O'Brien; Julie Playfair; Leon Chapman; Linda M. Schachter; Stewart Skinner; Joseph Proietto; Michael Bailey; Margaret Anderson.
JAMA. 2008;299(3):316-323.
Vol. 299 No. 3, January 23, 2008.

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