Major Finding: Type 2 diabetes resolved in 93% of patients who underwent gastric bypass surgery, compared with 47% of patients who underwent sleeve gastrectomy.
Data Source: A double-blind, randomized trial comparing gastric bypass surgery, which excludes the duodenum, against sleeve gastrectomy, which does not bypass the duodenum, in 60 patients with poorly controlled type 2 diabetes and a BMI of 25–35 kg/m
Disclosures: No financial conflicts of interest were reported.
For non–morbidly obese patients with poorly controlled type 2 diabetes, gastric bypass surgery with exclusion of the duodenum was much more likely to resolve diabetes than was a simpler, purely restrictive procedure that does not exclude the duodenum, according to a double-blind, randomized trial.
However, the relative safety of the purely restrictive procedure may make it a better first choice than gastric bypass surgery for many patients, the study's authors said.
Diabetes resolved in 28 of 30 (93%) patients who underwent gastric bypass, which prevents contact between ingested food and the duodenum, compared with 14 of 30 (47%) who underwent sleeve gastrectomy, which does not prevent such contact. The study is the first randomized trial to examine surgical treatment's effect on non–morbidly obese patients with a body mass index (BMI) of less than 35 kg/m
Both groups of patients showed significant weight loss and improvement in such metabolic measures as waist circumference, hemoglobin A1c levels, and insulin levels. But those improvements were more frequent and more extensive in the patients who underwent full gastric bypass.
The findings strongly support the hypothesis that the duodenum plays a large role in the resolution of diabetes following bariatric surgery. “The mechanism seems to relate to postprandial glucose metabolism rather than to an increase in insulin secretion, and is independent of weight reduction,” said Dr. Wei-Jei Lee of Min-Sheng General Hospital, National Taiwan (China) University, and associates (Arch. Surg. 2011; 146:143-8).
In the double-blind study, 60 patients aged 34–58 years were randomly assigned to undergo one of the two operations using standard laparoscopic techniques. The mean BMI was 30.3, and the average age was 45 years. All patients had been seeing an endocrinologist for type 2 diabetes for at least 6 months but continued to have poorly controlled disease, with a mean HbA1c level of 10% (range, 7.5%–15%).
The primary end point – glycemic control at 12 months without the use of oral hypoglycemic agents or insulin – was achieved by significantly more patients in the gastric bypass group (93%) than in the sleeve gastrectomy group (47%).
“These results corroborate previous reports that gastric bypass may achieve an 80% diabetes mellitus remission and pure restrictive-type procedures may achieve a rate of approximately 50%,” the researchers wrote.
Although weight loss was similar between the two groups, patients who underwent full gastric bypass also showed a smaller waist circumference, lower fasting plasma glucose levels, lower HbA1c levels, and lower blood lipid levels – in short, a higher rate of remission of the metabolic syndrome (93% vs. 40%). Their blood pressure, insulin levels, and C-peptide levels also were lower than were those in the sleeve gastrectomy group.
There were no deaths or major complications, and minor complications developed in three patients in each group.
However, it is important to note that restrictive procedures such as sleeve gastrectomy or gastric banding are 10-fold safer than the more-complex gastric bypass procedures, the investigators cautioned. In addition, those two restrictive procedures avoid the long-term sequela of micronutrient deficiency that sometimes follows duodenum exclusion. Thus should be considered the first choice for many patients, Dr. Lee and colleagues said.
In contrast, gastric bypass might be a better choice for patients with metabolic syndrome or hyperlipidemia, they noted.
The mechanism by which exclusion of the duodenum and upper jejunum reverses diabetes (the so-called foregut theory) has not been fully explained, and “without data regarding the change in gut hormones, such as glucagon, gastric inhibitory peptide, and glucagon-like peptide 1, we cannot elucidate the underlying mechanisms,” the researchers added.
Given the 1-year follow-up of the study, the study's authors said they also could not confirm the durability of diabetes remission in such patients, or the influence of future changes in weight.