Sept. 15, 2008 -- Gastric bypass
surgery may be less successful for patients with
diabetes and patients with a larger stomach pouch size, say researchers
from the University of California, San Francisco.
The researchers examined data from 310 patients who underwent
gastric bypass surgery at the University of California, San Francisco,
Medical Center between 2003 and 2006.
Gastric bypass surgery is a common surgical treatment in North America to
obesity. During the procedure, a surgeon reduces the size of a person's
stomach to create a smaller pouch. This allows a person to feel full sooner.
The pouch is then connected to a lower section of the small intestine,
bypassing part of the small intestine, to limit the calories and nutrients the
body can absorb.
"When performed in high-volume centers and with a low rate of complications,
gastric bypass provides sustained and meaningful
weight loss, significant improvement in quality of life, improvement or
resolution of obesity-associated comorbidities and extended life span," the
Even so, 5% to 15 % of patients do not lose a successful amount of
To understand why, the researchers observed the study's participants for 12
months following their surgery. They examined variables that could affect a
patient's ability to lose a successful amount of weight, including older age,
gender, greater initial weight and BMI, race, marital status, insurance status,
the presence of
type 2 diabetes, and larger pouch size.
Poor weight loss was defined as losing 40% or less of the excess body weight
12 months after the surgery and good weight loss as losing more than 40% of the
Before the surgery, their average
body mass index (BMI) was 52. One year later, it was 33.9 on average.
Thirty-eight of these patients (12.3%) had poor weight loss with a final
average BMI of 43.8. The 87.7% of participants who had successful weight loss
had an average BMI of 32.5.
After taking into account many variables, the researchers found that having
diabetes, or a larger stomach pouch were linked to higher odds for poor weight
loss after gastric bypass surgery. When they looked specifically at patients
with diabetes, they found that poor weight loss was more strongly linked to
those who were taking insulin compared to patients without diabetes.
The reasoning is that people with diabetes may be taking insulin or some
other type 2 diabetes drug that affects weight loss after surgery. For example,
these patients may also increase their
caloric intake to offset episodes of
low blood sugar.
Also, one of the most important aspects of gastric bypass surgery is making
the stomach pouch smaller, because it limits a person's ability to overeat.
Yet, many surgeons estimate pouch size rather than using a sizing balloon, a
tool used to precisely measure the gastric pouch, the researchers say.
"We conclude that gastric bypass provides good or excellent weight loss for
most patients," they continued. "However, diabetes and larger pouch size are
independently associated with poor weight loss after gastric bypass. Changes in
the use of diabetes medications may reduce
the risk of poor weight loss among diabetics undergoing gastric bypass.
Detailed attention to the creation of a small gastric pouch is essential for
achieving the best results."