{mosimage}Obese patients with type 2 diabetes who had gastric banding surgery lost more weight and had a higher likelihood of diabetes remission than did patients who used conventional methods for weight loss and diabetes control, according to a preliminary, unblended, randomized controlled trial reported in the January 23 issue of the Journal of the American Medical Society.
"Significant sustained weight loss achieved using bariatric surgery has never been formally investigated as a treatment for type 2 diabetes in obese participants," write John B. Dixon, MBBS, PhD, from Monash University in Melbourne, Australia, and colleagues. "Several observational studies suggest substantial benefit, but these have generally been restricted to severely obese participants; to our knowledge, there have been no published randomized controlled trials."
The aim of this study was to evaluate whether surgically induced weight loss was associated with better glycemic control and with less need for diabetes medications than were traditional approaches to weight loss and diabetes control.
From December 2002 through December 2006, 60 obese patients (body mass index >30 and <40 kg/m2) with type 2 diabetes diagnosed in the past 2 years were recruited from the general community to established treatment programs at the University Obesity Research Center in Australia. Participants were randomly assigned to conventional diabetes therapy emphasizing weight loss by lifestyle change or to conventional diabetes care with laparoscopic adjustable gastric banding surgery.
The primary endpoints included remission of type 2 diabetes, defined as fasting glucose level less than 126 mg/dL (7.0 mmol/L) and glycated hemoglobin (HbA1c) value lower than 6.2% in the absence of glycemic therapy. Secondary endpoints were weight and components of the metabolic syndrome, and analysis was by intent-to-treat.
Two-year follow-up was completed by 55 (92%) of the 60 patients enrolled. In the surgical group, 22 of the patients (73%) had remission of type 2 diabetes, as did 4 patients (13%) in the conventional-therapy group, yielding a relative risk of remission for the surgical group of 5.5 (95% confidence interval, 2.2 – 14.0).
At 2 years, mean weight loss was 20.7% ± 8.6% in the surgical group and 1.7% ± 5.2% in the conventional-therapy group (P < .001). Remission of type 2 diabetes was associated with weight loss (R2 = 0.46; P < .001), as well as with lower HbA1c levels at baseline (combined R2 = 0.52; P < .001). Neither group developed any serious complications.
"Participants randomized to surgical therapy were more likely to achieve remission of type 2 diabetes through greater weight loss," the authors write. "These results need to be confirmed in a larger, more diverse population and have long-term efficacy assessed…. 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."
Study limitations include participation restricted to those with a recent diagnosis of type 2 diabetes; extensive experience of the bariatric surgical team with the gastric banding procedure, limiting generalizability to other institutions; insufficient power for safety or to detect differences in hard endpoints, such as mortality or cardiovascular events; duration of follow-up limited to 2 years; and missing follow-up data in 5 patients.
"An important finding of this study is that degree of weight loss, not the method, appears to be the major driver of glycemic improvement and diabetes remission in obese participants," the authors conclude. "This has important implications, as it suggests that intensive weight-loss therapy may be a more effective first step in the management of diabetes than simple lifestyle change. This study shows that few participants achieved remission with a body weight loss of less than [10%], a level expected to produce important health benefits."
This study was funded by Monash University, which received an unrestricted grant from Allergan Health. The manufacturers provided the laparoscopic adjustable gastric bands (Allergan Health) and the laparoscopic ports (Applied Medical) without charge. Some of the authors report various financial arrangements with the National Health and Medical Research Council, Allergan Health, Novartis, Eli Lilly, Novo Nordisc, Sanofi Aventis, Alphapharm, and/or Abbott Australia.
In an accompanying editorial, David E. Cummings, MD, and David R. Flum, MD, MPH, from the University of Washington, Seattle, call these findings "clear and striking."
"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, in the face of an expanding pandemic," they write. "Addressing these issues requires time and resources, but in this era of advanced diabetes research, the insights already beginning to be gained by studying surgical interventions for diabetes may be the most profound since the discovery of insulin. As a result, the future looks brighter for patients."
Dr. Cummings and Dr. Flum report various financial arrangements with the National Institutes of Health, Tyco, Johnson & Johnson, Autosuture, Allergan, Roche, Storz, GI Dynamics, Amylin, and/or Power Medical Interventions.
JAMA. 2008;299(3):316–323, 341–343.
