With commentary by lead researcher Flemming Dela, MD, of the Center for Healthy Aging and Department of Biomedical Science at the University of Copenhagen.
Weight loss surgery can send type 2 diabetes into remission for years, meaning no more blood-sugar drugs. But for some, diabetes returns. Now, a recent Danish study suggests a way to predict long-term success before surgery: By testing the health of insulin-producing beta cells.
In a small but well-designed study published in The Journal of Physiology, scientists measured insulin output before and after Roux-en-Y gastric bypass surgery in 18 people with type 2 diabetes and in 15 people without diabetes. Four months later, 57% of the type 2’s with the healthiest beta cells no longer had diabetes compared to none of those with poor-performing cells. After 18 months, diabetes was in remission for 71% of those with the best-functioning beta cells but just 38% with the poorest-producing cells.
"Our study shows that the patients’ ability to produce insulin is decisive for whether or not the procedure eliminates diabetes,” says lead researcher Flemming Dela, MD, of the Center for Healthy Aging and Department of Biomedical Science at the University of Copenhagen. “Measuring the insulin cells’ performance before surgery can thus provide us with a much better basis from which to predict who will actually benefit from the surgery.”
Remission in this study meant an A1C below 6%, fasting blood sugar levels below 102.6 mg/dL and no need for diabetes medications anymore. Remission rates in the months after weight loss surgeries like gastric bypass and sleeve gastrectomy are often high. In a 2009 University of Minnesota review of studies involving more than 7,000 type 2s, 80% saw diabetes resolve in the first two years after surgery. But long-term success rates are usually lower. In a University of Pittsburgh study that tracked 61 surgery patients, 40% were enjoying a complete or partial remission three years later. And many who don’t get remission still get better diabetes control and need fewer drugs at lower doses.
That’s an important point—and a reason to consider weight loss surgery even if diabetes may return, says DiabeticLifestyle Medical Advisory Board member Scott Cunneen, MD, Director of Bariatric Surgery at Cedars-Sinai Medical Center in Los Angeles, CA. “People with type 2 diabetes want to know whether bariatric surgery will make their diabetes go away. But more and more people also understand that even if blood sugar levels rise again, there are major health benefits to losing a significant amount of weight. Diabetes is usually easier to control, with fewer highs and lows. Remission and better control can postpone complications for up to 10 years. And you may need lower doses of medications or fewer drugs. As you lose weight, you may also get help with high cholesterol and high blood pressure. Surgery can be seen as a very effective treatment for diabetes.”
Researchers are still sorting out exactly how weight loss surgery improves diabetes, and why it doesn’t work for everyone. Weight loss improves the body’s ability to obey insulin’s commands to absorb blood sugar. Cutting calories, eating a healthier diet and getting more exercise after surgery also help. Surgery may also alter levels of gut hormones or even change the balance of digestive-system bacteria in beneficial ways. But those factors haven’t fully explained why remission happens for some people who lose weight after surgery but not for others.
Dr. Dela says this new study shows that it takes more than better insulin sensitivity. You also need healthy beta cells that can pump out enough insulin to push blood sugar into receptive cells. And over time, people with type 2 diabetes may lose beta cells and the cells they still have may not produce as much insulin.
While there’s no doctor’s office test yet that directly measures beta-cell function in a reliable way, weight loss surgery researcher Sangeeta Kashyap, MD, an endocrinologist and associate professor of medicine at the Cleveland Clinic Lerner College of Medicine says other clues can help you and your doctor assess how well your beta cells are doing. “Long duration of diabetes indicates impaired ability of the pancreas to produce insulin and therefore could make a person less responsive to the weight loss and hormonal benefits of bariatric surgery,” she says. People with type 2 diabetes who use insulin may also have reduced beta-cell function. In a recent study, she and other Cleveland Clinic researchers found that people who’d had type 2 for less than eight years and didn’t use insulin were most likely to achieve remission. But even those who didn’t hit that target found their blood sugar easier to control.