Bariatric Surgery For Moderate Obesity With Diabetes: More Evidence Needed
Lead author Melinda Maggard-Gibbons, a surgeon at the David Geffen School of Medicine at University of California, Los Angeles (UCLA), and colleagues, came to this conclusion after reviewing more than 30 studies that compared moderately obese diabetic patients who underwent bariatric surgery with counterparts treated non-surgically with drugs and dieting.
Although they found that bariatric surgery was linked with better short-term control of abnormal blood sugar and more weight loss, they say the results come from a small number of studies and trial centers and more evidence is needed of how patients fare in the longer term before the approach can be more widely recommended.
Maggard-Gibbons says in a statement:
"Bariatric surgery for diabetic people who are not severely obese has shown promising results in controlling glucose."
"However, we need more information about the long-term benefits and risks before recommending bariatric surgery over non-surgical weight-loss treatment for these individuals," she adds.
The researchers say there is not enough evidence of how patients are faring two or more years after their surgery. There is not enough information on longer term complication rates and side effects, for instance.
Bariatric surgery procedures such as gastric bypass (where the top of the stomach is made into a small pouch and connected to the small intestine) and gastric banding (where an adjustable band constricts the top part of the stomach) are now commonly used to help severely obese people lose weight and manage related illnesses.
Severely obese means having a body mass index (BMI) of 40 or more. BMI is a ratio of weight to height (weight in kilos divided by square of height in metres). A person with a height of 1.78 metres (5 ft 10 in) and weight of 127 kg (280 lb) has a BMI of 40 and is classed as severely obese.
Bariatric surgery is generally only considered an option for people with a BMI of 40 or more, or for people with a BMI of 35, if they also have diabetes.
Bariatric surgery is also being proposed as a treatment for diabetes in less obese patients, but there is no general agreement among medical bodies about this.
For example, in 2006, while the federal Centers for Medicare & Medicaid Services in the US would not give coverage for less obese patients, the US Food and Drug Administration approved gastric banding for patients with BMI of 30 to 35 with an obesity-related illness, such as diabetes.
So for the study, Maggard-Gibbons and collegues, looked at the published evidence on use of bariatric surgery in people with a BMI of 30 to 35 who also had diabetes.
They searched well-known databases for articles published between 1985 and 2012. From an initial pass they found 1,291 articles, from which: "32 surgical studies, 11 systematic reviews on nonsurgical treatments, and 11 large nonsurgical studies published after those reviews" met their criteria for a pooled analysis.
The results showed that compared to non-surgical interventions, bariatric surgery was linked with better control of blood sugar and more short-term weight loss in diabetic patients with a BMI in the range 30 to 35.
Plus, gastric bypass seemed to achieve more dramatic improvements than gastric banding.
But a lot of the studies only included a small number of patients whose procedures were carried out by one surgeon at one academic center.
The authors say this does not mean the same results would be achieved in general clinical practice.
So they conclude that before recommending bariatric surgery for less obese patients, they would like to see more larger studies showing the benefits to this group.
The federal Agency for Healthcare Research and Quality also helped to support the study.
The study follows one published in JAMA Surgery recently that analyzed a large sample of insurance claims data and concluded bariatric surgery is not associated with reducing long term health care costs.
Written by Catharine Paddock PhD