More than one third of severely obese adults who achieved complete remission of type 2 diabetes mellitus (T2DM) within 5 years after bariatric surgery relapsed within 5 years of that initial remission, according to the largest community-based study to date of long-term outcomes after bariatric surgery, published online November 18 in Obesity Surgery.
David E. Arterburn, MD, MPH, general internist and associate investigator at the Group Health Research Institute in Seattle, Washington, and colleagues conducted a retrospective cohort study of 4434 adults with T2DM who underwent gastric bypass surgery at 3 integrated healthcare centers between 1995 and 2008. The centers were Health Partners in Minnesota, Kaiser Permanente Northern California, and Kaiser Permanente Southern California.
More than half (55.5%) of the patients underwent open Roux-en-Y gastric bypass (RYGB), and 44.5% underwent laparoscopic RYGB. However, remission rates between the 2 methods were not significantly different. The number of surgeries per year ranged from 9 (0.2% of the total number of procedures) during 1995-1996 to 1227 during 2007-2008 (27.7% of the total number of procedures).
Overall, 76.9% (95% confidence interval [CI], 75.3% - 78.6%) of the patients achieved partial T2DM remission within 5 years of surgery, and 68.2% (95% CI, 66.4% - 70.0%) achieved complete remission within 5 years. Of the patients with complete T2DM remissions, 35.1% (95% CI, 32.0% - 38.4%) had a relapse within 5 years of initial complete remission.
The study population was 77.1% women, and 70.1% of patients were taking oral medications at the time of surgery. Risk factors for relapse included older age (adjusted hazard ratio
for 5-year increase in age, 1.07; 95% CI, 1.01 - 1.14), increased levels of HbA1c (≥6.5%), and longer duration of diabetes (HR for each additional year of diabetes, 1.13; 95% CI, 1.09 - 1.17), all at the time of surgery. The rate of relapse was higher (40.1%) using the partial remission threshold. The adjusted HRs for relapse were particularly high for those using insulin (HR, 1.91; 95% CI, 1.48 - 2.45) and those whose HbA1c levels were 10% or higher (HR, 2.07; 95% CI, 1.42 - 3.02) at the time of surgery. Adjustments were made for age at surgery, sex, year of surgery, type of surgery, HbA1c level at the time of surgery, diabetes medication use at time of surgery, and diabetes duration.
"The results presented here shed new light on the importance of preoperative patient selection and counseling when one of the goals of surgical intervention is durable diabetes remission," the researchers write. "We consistently found that those treated with insulin were less likely to remit and more likely to relapse than those not on insulin prior to surgery."
Limitations of the study include the fact that first-year remission rates were significantly lower than rates previously published and that insufficient data were available to analyze whether race/ethnicity or changes in body weight made a difference. In a subpopulation analysis of patients with body weight data in their records, however, the researchers found that body weight at the time of surgery did not statistically affect whether patients remitted or relapsed.
"Despite these limitations, we believe that our results have a number of significant clinical and research implications for diabetes care," the authors write. "Patients should be counseled that bariatric surgery alone does not reliably 'cure' diabetes. However, the remission rates achieved by RYGB appear to be far better than what could be achieved by any other behavioral or drug treatment.... [O]ur data suggest that the effect of bariatric surgery on durable diabetes remission is likely to be strongest among those who are earlier in the course of their diabetes, although this finding should be confirmed in future prospective, randomized controlled studies," they conclude.
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