Gastric bypass may be an effective treatment for type 2 diabetes in patients who are only mildly obese (body mass index 30-35 kg/m2).
Note that 88% of patients had remission of their diabetes, with an additional 11% having glycemic improvement, and that most changes occurred in the first 6 months, with the mean HbA1c falling from 9.7% to 5.9%.
Gastric bypass may be an effective treatment for type 2 diabetes in patients who are only mildly obese, researchers said here.
The vast majority of patients (88%) had remission of their diabetes, bringing their glycated hemoglobin (HbA1c) to 6.5%, even after coming off their anti-diabetic drugs, David Cummings, MD, of the University of Washington in Seattle, and colleagues reported online in Diabetes Care and during a session at the American Diabetes Association meeting here.
An additional 11% achieved an HbA1c below 7% while decreasing their use of oral diabetic drugs and withdrawal of insulin, they found.
Gastric bypass "is a safe, effective procedure to ameliorate type 2 diabetes and associated comorbidities," they wrote, adding that their findings justify further trials to clarify whether bypass "should be broadened and might be viewed primarily as a 'metabolic' rather than 'bariatric' surgery."
Severely obese patients are often rid of their type 2 diabetes when they have gastric bypass surgery. An NIH consensus statement, however, limits the use of bariatric surgery to patients with a body mass index (BMI) of at least 35 kg/m2 in addition to comorbidities, the researchers said.
But patients with a BMI between 30 and 35 kg/m2 constitute the majority of obese patients, and many have diabetes. Thus, researchers have asked whether roux-en-Y gastric bypass should be offered to this population to treat type 2 diabetes.
They assessed 66 patients with a BMI of 30 to 35 kg/m2, all of whom had severe, long-standing diabetes, with a mean disease duration of 12.5 years and an HbA1c of 9.7% despite insulin or oral diabetes drugs.
All patients had roux-en-Y gastric bypass surgery and were followed for a median of 5 years.
The main outcomes included safety and the percentage of patients who had remission of their diabetes as measured by reaching an HbA1c of less than 6.5% without the use of medications.
Cummings and colleagues found that 88% of patients had remission of their diabetes, with an additional 11% having glycemic improvement, reaching an HbA1c below 7% with decreased use of oral diabetes drugs and withdrawal of insulin.
Overall, most changes occurred in the first 6 months, with the mean HbA1c falling from 9.7% to 5.9% (P<0.001) even though the majority of patients stopped using diabetes medications, they reported.
Mean fasting plasma glucose also fell from 156 mg/dL to 97 mg/dL (P<0.001).
Patients also generally had major reductions in waist circumference and total body weight (P<0.001), they found.
However, weight loss didn't always correlate with glycemic improvements, which is "consistent with weight-independent antidiabetes mechanisms" of gastric bypass, they wrote.
Cummings said there was "no hint of correlation at any time point" between changes in body weight and changes in glycemia.
"Diabetes goes away really fast before weight loss," Cummings said. "There must be additional weight-loss-independent mechanisms that contribute to this."
Patients also had significant improvements in cardiovascular risk markers, with resolution of hypertension, hypercholesterolemia, and hypertriglyceridemia in 58%, 64%, and 58% of patients, respectively.
The predicted 10-year risk of cardiovascular disease also fell significantly, with patients having the following:
71% lower risk of coronary heart disease (P=0.001)
84% lower risk of fatal coronary heart disease (P=0.001)
50% lower risk of stroke (P=0.01)
57% lower risk of fatal stroke (P=0.009)
There was no mortality, major surgical morbidity, or excessive weight loss in the trial, they reported.
Only one patient had no clear change in diabetes status, but it was not certain why this was the case. There were no clear differences as to why the patient didn't improve, and he didn't appear to have been misdiagnosed with type 1 diabetes.
"We looked hard at this guy to see if there was anything different about him," Cummings said. "It wasn't type 1, and the duration of diabetes and weight loss was about same [as the rest of the cohort]. We couldn't figure out why he didn't respond."
Cummings and colleagues said the diabetes remission rate in this trial is comparable to that seen in trials of bariatric surgery in conventional patients with a BMI of 35 kg/m2 or higher.
"Although lowering the BMI threshold for roux-en-Y gastric bypass in patients with type 2 diabetes from 35 to 30 kg/m2 would be a modest numerical change, it would affect a very large population because the BMI distribution peak among diabetic patients lies within this range," they wrote, adding that it "would have far-reaching implications for diabetes care."
"It's not a big numerical change, but it catches a lot of patients with diabetes," Cummings added.
They noted, however, that additional data are needed from randomized controlled trials before gastric bypass can be routinely recommend to treat diabetes in this population.
Still, Cummings said that "a lot of us in this field think that [the NIH guidelines on bariatric surgery] need to be revised."
The study was supported by the Municipal Health Authority of Marcia Maria Braido Hospital in Sao Paolo.
The researchers reported relationships with Johnson & Johnson, Covidien, and Ethicon Endo-Surgery.
Cohen RV, et al "Effects of gastric bypass surgery in patients with type 2 diabetes and only mild obesity" Diabetes Care 2012; online
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