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Baseline HbA1c, weight loss after bariatric surgery predict type 2 diabetes relapse
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Among adults with obesity and type 2 diabetes who underwent bariatric surgery and experienced diabetes remission at their first follow-up appointment, baseline HbA1c and excess body weight loss 1 year after surgery were independent predictors of diabetes relapse over 5 years, according to findings published in the International Journal of Obesity.
The definition of type 2 diabetes recurrence after bariatric surgery varies across studies, and disease relapse rates are underreported, Davide Carvalho, MD, PhD, associate professor at the University of Porto in Portugal, and colleagues wrote in the study background.
“While predictors of [type 2 diabetes] remission are relatively well-defined, those that can predict relapse are still under investigation as their identification requires longer follow-ups,” the researchers wrote. “These pitfalls can lead to patients’ reluctance in accepting a treatment with such an uncertain result and to physicians’ difficulties in choosing the appropriate bariatric procedure and in managing [type 2 diabetes] after it.”
In a retrospective, observational study, Carvalho and colleagues analyzed data from 110 patients with obesity (BMI 35 kg/m²) and type 2 diabetes who underwent bariatric surgery and were followed for 5 years by the Multidisciplinary Group for Surgical Management of Obesity at Centro Hospitalar Sao Joao in Porto, Portugal (mean age at enrollment, 50 years; mean BMI, 43.9 kg/m²; mean preoperative HbA1c, 6.88%). Follow-up included at least one yearly visit in which patients provided blood samples and were evaluated by an endocrinologist. Within the cohort, 56.4% underwent Roux-en-Y gastric bypass, 32.7% underwent laparoscopic adjustable band gastroplasty and 10.9% underwent sleeve gastrectomy. Researchers assessed glycemic and lipid profiles, excess body weight loss (difference between initial BMI and a target BMI of 25 kg/m²) and weight regain at follow-up visits. Complete type 2 diabetes remission was defined as an HbA1c of less than 6% and no antidiabetes medication use; partial remission was defined as an HbA1c less than 6.5% and no antidiabetes medication use. Patients who attained diabetes remission were accounted for cumulate remission, whereas prevalent remission was considered only for patients in remission during evaluation, the researchers wrote. Diabetes recurrence was defined as an HbA1c of at least 6.5% or the need for antidiabetes medication.
At the first postoperative visit, 47.3% of patients achieved type 2 diabetes remission, with the rate remaining relatively stable after year 1, according to researchers. Partial remission rates fluctuated between 50.9% and 51.8%. At year 5, complete and partial diabetes remission rates were 57.3% and 63.8%, respectively.
The researchers observed type 2 diabetes recurrence in 10 of 63 patients (15.9%) who attained complete remission, recurring an average 20.4 months after achieving remission. At the end of follow-up, mean HbA1c was still lower than the preoperative level (mean difference, 1.02%; P < .05).
In binary logistic regression models, preoperative HbA1c (beta = 1.06; 95% CI, 1.01-1.11) and excess body weight loss in the first year after surgery (beta = 0.49; 95% CI, 0.26-0.95) were independent predictors of type 2 diabetes recurrence. There were no between-group differences regarding age, sex, preoperative BMI or use of insulin or oral antidiabetes drugs.
In an analysis of patients who attained an HbA1c of less than 6% at year 1, researchers observed no differences in the chance of avoiding type 2 diabetes relapse at year 2 when comparing patients who were kept on metformin vs. those who were not (P = .08).
“The low but still significant relapse rates we have described reinforce the need of a multidisciplinary follow-up of obesity-related comorbidities even after attaining their apparent resolution,” the researchers wrote, adding that maintaining metformin in patients who achieved an HbA1c lower than 6% did not seem to influence relapse rates during follow-up.
“However, metformin pleiotropic benefits go well beyond glycemic control and future studies should continue to address this subject,” they wrote. – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.
Perspective
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This study, which was observational, confirms what we have observed in our randomized controlled trial (Schauer PR, et al. N Engl J Med. 2017;doi:10.1056/NEJMoa1600869). In our study, we had patients who underwent sleeve gastrectomy, gastric bypass and medical therapy, and we looked at diabetes relapse rates following diabetes remission after surgery. We found that relapse rates are higher as you go further out from surgery. At 5 years, relapse rates were 80% for sleeve gastrectomy and 50% for gastric bypass. When you look at baseline characteristics, the severity of diabetes, typically reflected in the baseline HbA1c, does influence the risk for diabetes relapse. We found that diabetes duration — which can be a moving target and is hard to correctly document — was the most important factor to predict remission. When we looked at weight loss, we found that weight loss within the first year is highly predictive of a good glycemic response. Additionally, weight regain was not predictive of glycemic response.
We can certainly work to reduce the relapse rate. We have to select the appropriate candidates to have bariatric surgery. I tell patients when their diabetes duration is early — within the first 5 years of diagnosis — they are more likely to have a favorable response. To keep diabetes away, we want them to lose as much weight as possible right after surgery and keep it off long term, which can pose a challenge. We also try to optimize diabetes treatment prior to surgery. Having a well-controlled HbA1c is very important before surgery, so beta cells can respond positively.
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