Gastric banding for diabetes   (January 24, 2008)

The Journal of the AMA has recently published the results of a study titled "Adjustable Gastric Banding and Conventional Therapy for Type 2 Diabetes: A Randomized Controlled Trial" (JAMA, 2008;299(3):316-323).

In this study, 60 obese people with recent-onset T2DM were randomized to receive either surgery called laparoscopic adjustable gastric banding (LAGB), or conventional medical therapy for their diabetes. Requirements included age between 20 and 60 years, body mass index of 30 to 40, diagnosis of diabetes within the previous 2 years, no evidence of diabetic kidney or eye disease, and able to understand and comply with the study process. The primary end points of the study related to glycemic control at 2 years after randomization.

Although the publication talks modestly about "conventional therapy," I should point out that the care given to the group that didn't get surgery was indeed excellent. According to the report, the Conventional-Therapy Program "delivered best available medical practice for the treatment, education, and follow-up of patients with type 2 diabetes. Patients had open access to a general physician, dietitian, nurse, and diabetes educator and had visits with at least 1 team member every 6 weeks throughout the 2 years. Medical therapies, including pharmaceutical agents, were determined by an experienced diabetologist on an individual basis. Lifestyle modification programs were individually structured to reduce energy intake, to reduce intake of fat ... and to encourage intake of low glycemic index and high-fiber foods. [Extensive ] physical activity advice [was given]. Lifestyle was the primary approach to weight loss, but very low-calorie diets and medications were discussed with all patients and used after consultation with the dietitian or general physician if the patient expressed a desire to use additional measures."

Several of the randomized patients dropped out during the study. One patient randomized to surgery withdrew from the study on the evening prior to scheduled operation and did not agree to be further followed up. Of the 30 people who were randomized to conventional therapy, four withdrew: three withdrew within the first month after randomization, and one withdrew 4 months after randomization.

Adverse events in the surgical group that were described included:

* One patient had the band removed on day 15 due to band intolerance.

* One patient developed a superficial wound infection over the access port site two weeks after it was placed, which resolved with intravenous antibiotics.

* Two patients developed gastric pouch enlargement, both at 10 months after placement, and were treated with nonurgent laparoscopic revisional surgery to remove and replace their bands.

* Other adverse events reported included postoperative febrile episodes in one patient. No cause was found, and the fever resolved. A minor hypoglycemic episode occurred in one patient and gastrointestinal tract intolerance to metformin in another.

Adverse events in the medical group included:

*Two patients had minor gastrointestinal tract adverse effects, and one had persistent diarrhea with metformin.

* One patient developed vasculitic rash, possibly related to rosiglitazone.

* One patient had multiple hypoglycemic episodes.

* One patient was admitted to hospital with angina and a transient cerebral ischemic episode.

* Two patients were intolerant of very low-calorie meal replacement.

Granted all this, how well did the surgery work? The authors state that "Remission of type 2 diabetes was achieved by 26 study participants (43%) at 2 years (22/30 [73%] randomized to the surgical program and 4/30 [13%] to the conventional therapy program) (P less than .001). This represented 76% and 15% remission rates among completers in the surgery and conventional-therapy groups, respectively." Or, more simply, the levels of HbA1c and fasting plasma glucose were significantly lower in the surgical group at two years. And the surgical group lost a lot more weight: The surgical group achieved a mean 20.0% body weight loss at two years, compared with 1.4% among the conventional-therapy group.

The authors conclude: "This randomized trial demonstrates that weight loss associated with adjustable gastric banding results in diabetes remission in the majority of obese participants recently diagnosed as having diabetes and was associated with greater improvements in features of the metabolic syndrome and use of related medications. While caution is required in interpreting the longer-term benefits of surgery and weight loss, this study presents strong evidence to support the early consideration of surgically induced loss of weight in the treatment of obese patients with type 2 diabetes."

These are striking results, and the authors should be congratulated for their efforts.

But should you run out and find a surgeon to band your stomach?

Probably not. If further follow-up shows continued improvement in diabetes control over longer periods of time, and if the results can also be shown in people with more severe diabetes, it may be worthwhile to consider such surgery. However, this study has several built-in biases: the first being that it wasn't double-blinded: everyone knew who got which therapy. Double-blinding such trials is indeed possible, by having all participants get an operation, in which half are banded, and half merely have their belly opened, and no banding - what's called a "sham operation". This concept wasn't mentioned in the publication, and it should be considered for future trials of LAGB for treating T2DM.

Second, the surgeons had extensive experience with the LAGB procedure, and it is well known that there's a correlation between the experience of the LAGB surgical team and incidence of early and late complications. Third, only small numbers of mild cases of T2DM were involved.

The one circumstance where I would be quite comfortable with this idea is if you have the opportunity to participate in a randomized clinical trial, where you would be participating in further study of whether or not the concept works. And of course, in such a case, there'd be a 50-50 chance whether you'd actually get surgery, or perhaps be randomized to receive excellent medical therapy. And if there's sham surgery as part of the trial, you'd definitely get yourself a new scar or two.

I'll be very interested to see the results of future trials.