Roughly Half of Obese Patients Who Have Bariatric Surgery Are Off Type 2 Diabetes Meds at 6 Years

Patients undergoing bariatric surgery for the treatment of obesity are more likely to stop medications for type 2 diabetes, as well as less likely to start antidiabetes medication, than are obese patients not treated surgically, according to the results of a large French study.

Even when medical therapy wasn’t stopped entirely, “it was often simplified,” write Jérémie Thereaux, MD, PhD (Caisse Nationale d’Assurance Maladie des Travailleurs Salariés, Paris, France), and colleagues in their paper published online February 14, 2018, ahead of print in JAMA Surgery. For example, 40% of patients using insulin at baseline had switched to another therapy at 6 years, and 57% of those taking two antidiabetic medications had switched to monotherapy.

Still, investigators warn that morbid obesity “remains a chronic disease even after bariatric surgery because 50.1% of patients with preexisting antidiabetes treatment remained on treatment 6 years after surgery.” The present study highlights the need for “careful lifelong follow-up to monitor obesity complications.”

Ildiko Lingvay, MD (UT Southwestern Medical Center, Dallas, TX), who was not involved in the study, said that stopping antidiabetes medication after bariatric surgery ultimately depends on the type on patient.

“When you’re thinking of an individual patient, it is highly variable,” she told TCTMD. “If you have a patient that maybe just developed diabetes in the last year or so, they are very likely to resolve their diabetes and have very good long-term outcomes in that their diabetes won’t come back. If you have somebody who’s had diabetes for 20 years, is on three drugs including insulin, and their glycemic control is really bad, I can guarantee they will get better [with surgery] but chances of them completely reversing their diabetes and becoming normoglycemic is very low.”

One in 10 Obese Patients Taking Type 2 Diabetes Medication

The observational, population-based cohort study looked at patients who underwent bariatric surgery in France between 2008 and 2009. Using data from the French national health insurance database, 15,650 surgical patients were matched by age, sex, body mass index (BMI), and antidiabetes treatment to control patients hospitalized for obesity in 2009 but who did not undergo bariatric surgery. Adjustable gastric banding was the most common surgical procedure, followed by gastric bypass and sleeve gastrectomy. 

Slightly more than 10% of patients in the surgical and control arms were taking antidiabetes medications. For those taking the drugs, 91.7% were taking metformin and one in five patients were taking insulin.

At 6 years, the rate of antidiabetic medication use dropped by 49.9% in patients treated with bariatric surgery, compared with a reduction of just 9.0% in patients treated without surgery (P < 0.001), report investigators. In addition to the higher rate of antidiabetes drug discontinuation, the rate of insulin use declined 40% in the surgery group but increased 119.8% among those not undergoing surgery. In multivariate analysis, all types of bariatric surgery were associated with drug discontinuation at 6 years, although the association was strongest for gastric bypass procedures (OR 16.7; 95% CI 13.0-21.4).

To TCTMD, Lingvay said that at academic medical centers, physicians are more likely to treat complex obese patients, many of whom have several obesity-related complications such as type 2 diabetes. At their center, she estimated roughly 30% of patients undergoing bariatric surgery have the disease.

Overall, when discussing the risks and benefits of bariatric surgery with their patients, Lingvay tells them that approximately two-thirds will be in diabetes remission following the procedure but over the next 5 to 10 years, approximately half of those patients will redevelop diabetes.

However, she stressed that even among those who redevelop the metabolic condition over the long term, “there is a good period of time without diabetes or normoglycemia,” which provides enormous benefit to the patient. She likened bariatric surgery to “turning back the clock” by 5 or 10 years. “It’s still a benefit,” she said. “So I think we need to get away from thinking in these black-and-white terms: diabetes or no diabetes. It’s actually a very grey continuum.”  

Less Likely to Start Medication With Surgery

In the French analysis, 1.4% in the bariatric-surgery group who were not taking antidiabetes medication at baseline had started at 6 years, compared with 12.0% of the control patients (P < 0.001). Again, all types of surgery were protective against starting antidiabetes drug therapy. In the multivariate analysis, individuals with a higher BMI at baseline, male sex, concomitant antihypertensive therapy, low income, and older age were all predictors of the need to start medication for type 2 diabetes.   

Lingvay said that even though bariatric surgery is indicated and approved for obesity, the surgery’s effects on obesity-related complications, such as type 2 diabetes, high cholesterol, hypertension, osteoarthritis, and sleep apnea, among others, are considered when making decisions about the risks and benefits of the procedure.

“The surgery is not just to lose weight. There’s also an additional benefit in improving these abnormalities some patients have already developed,” she said, noting that sleeve gastrectomy is the most common procedure performed today, mainly because it’s a simpler operation with fewer complications. While the results are good, sleeve gastrectomy wasn’t quite as strong a predictor of freedom from antidiabetes medication (OR 7.3; 95% CI 5.5-9.5) as gastric bypass surgery, she noted.

For this reason, Lingvay said the choice of procedure can be a tough one for patients. Both surgeries “get the job done, but gastric bypass gets you a little more.” If a patient isn’t that far advanced in terms of cardiometabolic disease, she recommends sleeve gastrectomy. For those further advanced in their disease course, gastric bypass is a better option. “It’s not about how much weight they need to lose,” she said. “It’s where they are on the metabolic continuum.”

In an editorial accompanying the study, Michel Gagner, MD (Florida International University, Miami), noted that while half of patients in the study were free from diabetes medication at 6 years, this represents just 800 patients. In France, nearly 3 million people have diabetes. “Is this the beginning of a battle of giants, a Titanesque clash between a pharmaceutical industry of billions of dollars that protects its interests versus a much smaller surgical devices group?” he wonders.

He notes that $38.8 billion is spent on antidiabetic drugs in the United States, an amount that would treat 1.3 million people surgically. In the past, surgeons responded to the “challenge of coronary artery disease by providing operations to millions of patients,” he writes. “Why can’t we do the same for type 2 diabetes?”