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Gastric bypass surgery may cure type 2 diabetes
Nonobese patients with diabetes may also benefit from the surgery.
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Some researchers are suggesting that gastric bypass surgery may represent a cure for type 2 diabetes and that doctors should consider more patients eligible for the procedure. Patients with type 2 diabetes benefit from gastric bypass surgery even if they are not obese, the researchers say.
At the 65th Scientific Sessions of the American Diabetes Association, Francesco Rubino, MD, assistant professor at the Catholic University of Rome and clinician at the European Institute of Telesurgery in Strasbourg, France, spoke about the effects of gastric bypass surgery on diabetes.
One explanation for the effect on diabetes is the reduction in patients’ caloric intake. “After gastric bypass surgery, these patients are getting very few calories,” he said. “In the subset of obese patients, this might explain the rapid decrease of plasma glucose. The surgical weight loss that occurs subsequently will guarantee the long-term maintenance of this effect.”
Rubino noted that this theory is only one possible explanation for the effects of gastric bypass surgery and that more clinical trials are needed to better understand this issue.
Effect of surgery
Rubino was recently involved in a study to examine the relationship between diabetes control and gastric bypass surgery.
“We wanted to know if diabetes resolution is a secondary outcome of obesity treatment or [if] is it a direct effect of gastric bypass surgery,” Rubino said. “If control of diabetes is a direct outcome of surgery, then the same effect should also occur in nonobese diabetic patients independent of caloric intake and weight gain.”
Rubino and his colleagues performed modified gastric bypass surgeries in a group of nonobese lab rats with diabetes.
“As part of this surgery, we did not reduce the size of the stomach at all,” Rubino said. “Although the stomach remained completely intact, we made a construction in the bypass that is proportional in intestinal length to what is done in humans.”
Courtesy of F Rubino |
The rats were followed for nine months after the surgery and compared to similar rats that did not have the surgery. A third group of rats that were given a reduced caloric diet was also studied.
Rats that had the surgery demonstrated no differences in food intake behavior. There were, however, significant differences in fasting glycemia.
“One week after surgery, fasting glycemia was lower in the bypass group and stayed lower for nine months of postoperative follow-up,” Rubino said.
The most striking effect was in glucose tolerance. “As early as one week after surgery, these rats had a 42% reduction in the area under the glucose curve and had no peak values higher than before the operation,” Rubino said.
The improvements in the surgery group were better than those seen in the diet group and were independent of caloric intake or weight loss.
Rubino and his colleagues conducted a second study comparing the effects of rosiglitazone (Avandia, GlaxoSmithKline) with the effects of gastric bypass surgery. In this study, half of the rats were given rosiglitazone and half underwent gastric bypass surgery.
“Both rosiglitazone and gastric bypass surgery were associated with improvements in glucose tolerance,” Rubino said. “These improvements were much better in the bypass group than in the rosiglitazone group. This is a remarkable point because an operation appears to be more insulin-sensitizing than an insulin-sensitizing drug.”
These findings suggest there is a direct antidiabetes effect of gastric bypass surgery. “The problem now is to find out why this is happening,” Rubino said. “What is the mechanism of action of gastric bypass surgery?”
These results also indicate that patients who were previously not considered appropriate candidates for gastric bypass surgery may benefit from the procedure. The surgery may help to control diabetes in nonobese patients.
“There is no reason to believe the cutoff we have today – a BMI of at least 35 – is the limit at which the operation would work,” Rubino said. “It is possible that other patients may also benefit from surgery. Clinical trials should determine the true risk/benefit ratio to find out which patients may make good candidates for surgery. I don’t know if BMI of 35 is a good criteria anymore.” – by Jay Lewis
For more information:
- Rubino F. Gastric bypass: A quick cure for diabetes? Presented at the 65th Annual Scientific Sessions of the American Diabetes Association. June 10-14, 2005. San Diego.
- Rubino F, Marescaux J. Effect of duodenal-jejunal exclusion in a non-obese animal model of type 2 diabetes: a nwe perspective for an old disease. Ann Surg. 2004;239(1):1-11.