Bariatric surgery can significantly reduce the need for insulin and can even induce complete remission of type 2 diabetes mellitus, but some forms of the procedure pose too much risk and should be shunned, said a diabetes specialist at the annual advanced postgraduate course held by the American Diabetes Association.
Depending on the type of procedure, weight loss in the first year following bariatric surgery can range from about 30 kg to more than 50 kg, and the surgery can reduce the risk of mortality for formerly obese patients by about 25%, said Dr. John Bantle, professor of medicine and director of the division of endocrinology and diabetes at the University of Minnesota in Minneapolis.
Dr. John Bantle
Bariatric surgery should be considered in type 2 diabetic patients with a body mass index greater than 35 kg/m2, and may also benefit patients with a BMI of 30-35, although there is not enough evidence to support the latter assertion, Dr. Bantle said.
"I would choose laparoscopic gastric bypass as the procedure to recommend. I think laparoscopic gastric banding doesn’t have enough efficacy, and duodenal switch has too many complications," he said.
Looking back at Look AHEAD
The most recent follow-up data from the Action for Health in Diabetes (Look AHEAD) study compared cardiovascular event rates among patients randomized to either an intensive lifestyle intervention or a diabetes support and education program. Analysis showed that the lifestyle intervention was associated with significantly more weight loss (–4.7% vs. –1.1% at 4 years, P less than .001), and with a more favorable change in fitness levels, hemoglobin A1c, systolic blood pressure, high-density lipoprotein cholesterol levels, and triglyceride levels (P less than .001 for all comparisons) (Arch. Intern. Med. 2010;170:1566-75).
However, in September 2012, the National Institutes of Health, acting on the advice of the trial’s data and safety monitoring team, halted the lifestyle intervention because the primary endpoint of reduction in cardiovascular events had not been reached and would be unlikely to do so in the 2 years remaining in the study.
Although the trial failed to meet the cardiovascular endpoint, there was no evidence of harm, and patients who were randomized to the intervention had reduced need for diabetes medications, less sleep apnea, and increases in both physical mobility and quality of life.
"In data that are still under analysis and not yet published, I think we are going to see that there was some benefit on microvascular complications," Dr. Bantle said.
Choose procedures wisely
If lifestyle interventions are not sufficient, bariatric surgery may be helpful, Dr. Bantle said. Procedures commonly used in the United States include laparoscopic gastric banding, Roux-en-Y gastric bypass, and increasingly, sleeve gastrectomy and biliopancreatic diversion with duodenal switch.
The latter procedure is similar to a jejunoileal bypass, an early type of bariatric surgery that is no longer performed due to the high complication rate. Biliopancreatic diversion with duodenal switch involves division of the stomach and creation of a small gastric pouch that is drained with a loop of intestine attached downward to the ileum toward its head, so that biliary and pancreatic drainage occurs through the small intestine before the digestive juices meet up with food for digestion and absorption toward the end of the intestinal tract.
"I think this procedure is a really bad idea; it’s too much like a jejunoileal bypass with anastomosis, and I advise all my patients who are considering bariatric surgery to decline the option to pursue this procedure," he said.
Evidence favors surgery
Reviewing the evidence, Dr. Bantle pointed to a 2005 meta-analysis of 147 studies of bariatric surgery for obesity, which showed a mean 30.2-kg weight loss at 12 months and 34.8-kg loss after 36 months in patients who had a gastric banding procedure, compared with 43.5 kg and 41.5 kg, respectively, for gastric bypass, and 51.9 kg and 53.1 kg for those who had surgery with a duodenal switch procedure (Ann. Intern. Med. 2005;142:547-59).
The study also showed, however, that the rate of adverse events, including reflux, vomiting, dysphagia, and dumping syndrome, was markedly higher for patients who underwent a duodenal switch, at 37.7%, compared with 7.0% for gastric banding and 16.9% for gastric bypass.
A 2007 Swedish study also saw a reduction in mortality at a mean of 10.9 years of follow-up among 2,010 obese patients who underwent bariatric surgery compared with 2,037 patients who received standard medical management. The hazard ratio for death in the surgical patients was 0.76 (P = .04). The most common causes of death were myocardial infarction, which occurred in 13 surgical patients and 25 controls, and cancer, which occurred in 29 surgical patients and 47 controls (N. Engl. J. Med. 2007;357:741-52).