More Evidence Bariatric Surgery Benefits Type 2 Diabetics’ Heart Health

“This study demonstrates that persons with obesity and type 2 diabetes who undergo bariatric surgery have lower rates of myocardial infarction (heart attack), ischemic stroke, and mortality,” says Fatima Cody Stanford, MD, MPH, an instructor of medicine and pediatrics at Harvard Medical School in Boston, who specializes in obesity medicine. Dr. Stanford was not involved in this study.

These findings further strengthen existing literature, including a study published in October 2018 in JAMA, which found that bariatric surgery was associated with a 40 percent reduced risk of heart attack and stroke in people with type 2 diabetes. According to the Centers for Disease Control and Prevention, adults with type 2 diabetes are 2 times as likely to die of heart disease compared with those without type 2 diabetes.

“What we found tells us that the excess heart disease risk with diabetes and obesity is potentially reversible if you can lose the weight,” says Steven Nissen, MD, chief academic officer of the Heart and Vascular Institute at Cleveland Clinic and the study’s senior author. That’s the reason that these findings are generating a lot of attention, he adds. “We didn’t know when we started this study whether or not the effects of obesity would be long-lasting, essentially permanent. These results suggest that they’re not permanent — they’re reversible with weight loss,” says Dr. Nissen.

‘Stunning’ Reduction in Heart Disease-Related and All-Cause Deaths

To conduct this observational study, researchers analyzed 13,722 people, consisting of 2,287 who underwent bariatric surgery and 11,435 who did not (considered the control group) — a 1:5 match of surgical to nonsurgical patients. Bariatric surgery helps people lose weight by altering the digestive system, sometimes by making the stomach smaller or changing the small intestine.

Scientists tried to balance the groups, though there were slight disparities in the surgical versus nonsurgical groups:

Sex 65.5 percent female (surgical group) versus 64.2 percent (nonsurgical group)
Race 19 percent black versus 25 percent
Age Average of 52.5 years old versus 54.8
Body Mass Index (BMI) Average of 45.1 versus 42.6
Blood Sugar Levels Average A1C of 7.1 percent for both groups (A1C is a two- to three-month average of blood sugar levels, according the the American Diabetes Association.)
Current Smokers 7 percent versus 14 percent

The primary outcome for the study was the incidence of major adverse cardiac events (MACE), which was defined as the first occurrence of coronary artery events, cerebrovascular events (like a stroke), nephropathy (kidney disease), and atrial fibrillation in addition to all-cause death.

Over a period of eight years, about 31 percent of the patients who had undergone bariatric surgery died or had one of the five conditions compared with about 48 percent of the patients who didn’t have surgery and followed normal standards of care — a 40 percent reduction.

The people who had surgery were also 41 percent less likely to die of any cause; 112 patients (10 percent) in the surgery group died compared with 1,111 (17.8 percent) patients in the nonsurgical group.

Those reductions are significant, especially when compared with efficacy of many of the drugs used in cardiovascular medicine, such as statins to lower cholesterol and blood pressure medicines, says Nissen. “We might get a 15 to 20 percent reduction in major cardiovascular events or mortality with those drugs,” says Nissen. “The effects that we saw with bariatric surgery were really large … that’s really huge. It’s stunning to see that kind of effect,” he says.

People in the surgery group had other improvements as well, researchers found. Compared with the nonsurgery group, they lost an average of 15 percent more weight, and their A1Cs fell by an average of 1.1 percent, reaching 6 percent. They also needed fewer drugs to control their blood sugar, blood pressure, and cholesterol than the group that didn’t have surgery.

Would these results be likely for people who use diet and exercise to lose a substantial amount of weight without surgery? Maybe, but maybe not, Nissen says. When a person is overweight or has obesity, the cells in the body grow less sensitive to the insulin that the pancreas releases. Weight loss can help the body use insulin more easily, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

Nissen believes a large part of the reductions in morbidity and mortality seen with the surgery are due to the weight loss, but it’s more than just the weight loss that’s causing the benefits. In bariatric surgery the intestines are rerouted in such a way that it changes a lot of the gut hormones and many other metabolic factors, Nissen says. “Some experts believe that the effects we see are due to more than just the weight loss, and that it might also be changes in the gut anatomy that make a difference,” he says.

Further Research Needed to Prove Benefits of Bariatric Surgery

Nissen says the next step is the more scientifically robust method of a randomized controlled trial in order to confirm these results. “In an observational study, there are unmeasured confounders that may make the people in the treatment group and people who are in the control group different. We did our best to balance those characteristics, but it’s never a perfect process,” says Nissen.

These results should encourage more conversations between physicians and patients with metabolic disease and obesity, says Stanford. “Only 1 percent of patients who meet criteria for bariatric surgery receive this intervention in the United States. We could help more people with these two disease processes if we were more likely to consider bariatric surgery for this patient population,” she says.

Nissen agrees. “Given what we now know about the therapy and the benefits, we need to consider it in more patients. We can save lives if we do that,” he says.

Who’s Eligible for Bariatric Surgery? A Glance at the Criteria

At the Cleveland Clinic, a person can potentially be a candidate for weight loss surgery if they meet any of the below criteria:

More than 100 pounds over ideal body weight
A BMI of over 40
A BMI of over 35 with severe negative health effects, such as high blood pressure or diabetes that is related to being severely overweight
Unable to achieve a healthy body weight for a sustained period of time, even through dieting with medical supervision

According to the American Society for Metabolic and Bariatric Surgery, metabolic and bariatric surgery can cost anywhere from $11,500 to $26,000. Yet the surgery can ultimately reduce overall health costs and improve patients’ own earning potential due to their improved health, the society notes.

Immediate risks of bariatric surgery include bleeding, blood cloths, lung problems, infection, gastrointestinal system leaks, and more rarely death, according to the Mayo Clinic.

If you’re considering bariatric surgery to lose weight and manage type 2 diabetes, consult your doctor on the pros and cons. “Doctors need to explain to patients what we know, what we don’t know, what we think can be done for them,” Nissen says, “and then help them make an educated decision about what’s right for them.”