It’s common knowledge that people with diabetes are at an increased risk of heart complications such as heart disease, stroke, and hypertension. But did you know about the link between type 2 diabetes and heart failure?
According to a report published in June 2019 in the journal Circulation, people with type 2 diabetes are two to four times more likely to develop heart failure than those without diabetes. The report also states that having diabetes or heart failure independently increases the risk of getting the other condition, and both conditions often occur together.
“There’s a misperception that if you prevent a heart attack, you prevent heart failure, so all you need to do is prevent coronary artery disease,” says Javed Bulter, MBBS, MPH, a cardiologist and a professor and chairman in the department of medicine at the University of Mississippi in Jackson. “While that is true, that’s only part of the story.”
Heart attack is a risk factor for heart failure, a condition in which the heart fails to efficiently pump oxygen-rich blood through the body. But experts are learning that people with type 2 diabetes develop heart failure through many other mechanisms.
“Prevention of heart failure is something we never focused on,” says Dr. Butler. “There’s been a gap in our thinking that we’re now trying to bridge.”
The connection between diabetes and heart disease starts with high blood sugar levels. Over time, high blood sugar in the bloodstream can damage the arteries, causing them to become stiff and hard, making it harder for the heart to pump blood efficiently.
“Research suggests that people with diabetes develop damage and dysfunction in the heart muscle,” says E. Dale Abel, MD, PhD, the chair of the department of internal medicine at the University of Iowa in Iowa City and the director of the Fraternal Order of Eagles Diabetes Research Center. “The question is whether this is driven exclusively by high blood sugar — it could also be caused by high levels of fatty acids in the blood, increased inflammation, or cellular dysfunction.”
The reason for this dysfunction remains unclear, but it's likely caused by a number of factors, he notes.
In a study published in January 2020 in the journal Mayo Clinic Proceedings, researchers followed people with and without diabetes with no known structural heart disease over a 10-year period, and found that participants with diabetes were still at increased risk of developing heart failure. Researchers believe this may be the result of inherent problems in people with diabetes, such as insulin resistance, BMI, and elevated glucose levels.
The results support the hypothesis that having diabetes is itself a risk factor for heart failure, Dr. Abel notes.
While the link between heart failure and diabetes has been known for decades by the medical community, the topic has gained recent interest because of SGLT2 inhibitors, a class of medication used to treat type 2 diabetes. SGLT2 inhibitors work by preventing glucose from being absorbed in the kidneys, which helps keep sugar levels in the blood low.
Several studies, including one published in November 2019 in the New England Journal of Medicine, found that dapagliflozin, an SGLT2 inhibitor, lowered the risk of heart failure among participants who received it, compared with those who received a placebo, whether or not those participants had diabetes.
“They are the only class of antidiabetic medications that have been shown in clinical trials to reduce the risk of heart failure,” says Abel.
Though current guidelines recommend using SGLT2 inhibitors for people with diabetes and heart failure, or those at high risk for a heart attack, whether it helps prevent heart failure in all people with diabetes has yet to be determined. SGLT2 inhibitors aren't yet recommended for everyone with diabetes, because studies have not yet been done in low-risk patients, particularly those who were recently diagnosed or whose diabetes is mild.
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While it may take years for someone with diabetes to develop heart failure, the danger shouldn’t be ignored. “It’s a slow process,” says Abel. “Some of the damage could be happening in the prediabetes stage.”
Prediabetes is when a person has blood sugar levels higher than normal, but not high enough to be diagnosed with type 2 diabetes. By keeping blood sugar levels in a healthy range, you can lower your risk of developing diabetes. “One of the biggest risk factors is being overweight or obese,” Abel says. “Following a healthy diet and exercising can reduce the risk of developing type 2 diabetes by 70 percent.”
Another way to prevent or lower the risk of heart failure is to pay attention to symptoms that are consistent with heart failure, like:
These can often be missed because people are too focused on cholesterol and blood sugar, says Abel, adding, “there needs to be an increased awareness in both physicians and patients.”