Gastric bypass has been shown to improve the long-term prognosis of patients with obese type 2 diabetes, outperforming dietary control and lifestyle interventions. A randomized clinical trial in the United States found that after 1 year of follow-up, 17 percent of Roux-en-Y anastomosis patients and 23 percent of gastric banding patients had completely normalized their blood glucose, and none of these patients participated in an organized weight loss program. Another similar study also showed partial remission of diabetes in 58% of Roux-en-Y anastomosis patients, compared with 16% of patients with intensive lifestyle interventions.
A prospective cohort study by Professor Sj?str?m at Sahlgrenska University Hospital in Gothenburg, Sweden, found that after 15 years of follow-up, 30% of patients undergoing bariatric surgery remained in remission, compared with 7% of matched patients undergoing non-surgical conventional treatment. Moreover, microvascular and macrovascular complications were also greatly reduced in the surgical group in that study. The long-term observations support the potential of bariatric surgery to cure diabetes.
The STAMPEDE randomized clinical trial, which included 150 patients with obese diabetes, found that at 3 years, diabetes remission rates were 38% for Roux-en-Y gastric bypass patients, 25% for sleeve gastrectomy patients, and 5% for patients treated with intensive drug therapy.
Overall, these findings support the conclusions of several studies such as the STAMPEDE clinical trial, noted Dr. Roslin, a bariatric surgeon at Lenox Hill Hospital in the United States. For obese patients, type 2 diabetes is a surgical disease until medications and behavioral therapies can provide fairly reliable data. However, given insurance barriers and clinician bias, bariatric surgery is still only available for a subset of diabetes candidates.
Dr. Courcoulas et al. at the University of Pittsburgh Medical Center noted that several key questions remain unanswered regarding the therapeutic role of bariatric surgery in type 2 diabetes, including the relative safety and efficacy of treatment options (surgical versus non-surgical treatment), the altered risk of future microvascular and macrovascular complications, the economic impact of these treatments, the short-term diabetic impact versus the degree of weight loss, the surgical type and other factors, etc.
The study by Dr. Courcoulas et al. included 69 single-center diabetic patients aged 25-55 years with a body mass index (BMI) of 30-40 kg/m2, and patients were randomized to treatment (10% of them were screened). Results showed the greatest weight loss at 1 year with Roux-en-Y gastric bypass, 27% relative to baseline, 17% in the gastric banding group, and 10% in the intensive lifestyle intervention (treatment as in the Look AHEAD clinical trial).
Partial remission of diabetes in this study was defined as a hemoglobin A1C <6.5% and a fasting glucose level of 100-125 mg/dL after drug discontinuation, which is consistent with the American Diabetes Association criteria. The study again showed comparable remission rates between the surgical groups. 50% in the Roux-en-Y anastomosis group, 27% in the gastric banding group and none in the lifestyle intervention group. These findings are fully consistent with previous clinical trials, depending on the threshold set for remission, the researchers said.
Although remission rates were comparable between the surgery groups, the findings need to be validated given the small study sample, the single-center clinical study, and the fact that no definitive conclusions can be drawn.
Nevertheless, there was no remission of type 2 diabetes in the lifestyle weight reduction intervention group. Therefore, these results suggest that laparoscopic gastric ligation (low risk and potentially reversible) may have an opportunity as a treatment option for patients with low BMI and type 2 diabetes mellitus.
The serious side effects in the Roux-en-Y anastomosis group were peptic ulcers requiring medication, and 2 patients in the gastric banding group were readmitted for dehydration, but no deaths occurred.
Another feasibility study, conducted by Dr. Goldfine et al. at the Joslin Diabetes Center in Boston, included 43 patients aged 21-65 years with uncontrolled diabetes on medication and a BMI of 30-42 kg/m2 who were randomly assigned to receive either Roux-en-Y anastomosis or lifestyle-based weight loss (treatment as in the Why WAIT intervention program).
The study showed that weight loss was greater in the surgical group, with all patients in this group losing at least 10% of their body weight within 3 months, while only 37% of patients in the lifestyle intervention group achieved this level. The proportion of patients with HbA1c <6.5% and fasting glucose levels below 126 mg/dL after discontinuation of medication increased 6.9-fold in the surgery group. The rate of complete remission of diabetes was not reported.
In addition, at 1 year, surgical treatment also improved systolic and diastolic blood pressure, HDL, and triglycerides, whereas lifestyle interventions had no such effect. This was despite cutting back on more anti-hypertensive and lipid-lowering medications after surgery.
Not surprisingly, the risk scores for heart disease and stroke UKPDS were reduced more in gastric bypass patients than in lifestyle intervention patients. Overall quality of life improvements were similar between groups, although weight-specific quality-of-life indicators improved more in the surgery group, which was associated with greater weight loss.
The Goldfine study team concluded that “until large randomized clinical trials begin, these differences may help inform diabetes treatment decisions and weight loss strategies for obese patients with type 2 diabetes.”
The Swedish Obese People Study aims to fill the same gap. The study is a prospective matched cohort study with subjects from 25 surgical units and 480 primary health care centers in Sweden.
Researchers screened 260 patients from thousands who chose surgery and 343 patients with type 2 diabetes who were receiving medication (usually recommended for lifestyle changes). The majority of the surgical group underwent vertical banding gastroplasty (87%), with the remainder receiving adjustable and nonadjustable gastric banding and gastric bypass. Diabetes remission in this study was defined as a blood glucose level <110 mg/dL without treatment with diabetes medication. this was slightly different from other studies.
The results of the study showed a significant difference between the groups after 2 years, with 72% diabetes remission in the surgery group and 16% in the control group.
Although disease remission rates decreased in both groups over a median follow-up time of 18 years, the cumulative incidence of microvascular complications remained below 56% in the surgically treated group, with rates of 20.6 and 41.8 per 1000 person-years in the surgical and control groups, respectively.
Similarly, the cumulative incidence of macrovascular complications was less than 32% in the surgical group, with rates of 31.7 and 44.2 per 1000 person-years in the surgical and control groups, respectively.
There were no differences between the different types of bariatric surgery groups for comparison. After correcting for multiple factors, the results remained unchanged.
The researchers noted, “In our study, weight loss was similar between gastric banding and gastric bypass after 10 years of follow-up, and there was no significant difference in diabetes remission rates between the two methods of treatment; inconsistencies between studies may be due to inadequate sample size or different definitions of diabetes remission, such as fasting glucose, hemoglobin A1C, or both. “