In June of 2022, a report from the American Diabetes Association highlighted heart failure as “an underappreciated complication of diabetes.” According to that report, up to 22% of people with diabetes will develop heart failure, and the incidence of heart failure within the diabetes community is increasing.
“Heart failure is the most prevalent cardiovascular complication in people with diabetes,” says Dr. Rodica Pop-Busui, a professor of diabetes at the University of Michigan and president of medicine and science at the American Diabetes Association. “In the U.S. alone there are 37 million people diagnosed with diabetes, and heart failure in this population is a very serious health care problem that needs to be addressed before it reaches more advanced and more costly stages.”
For a time, it was thought that heart failure might mainly affect people with Type 2 diabetes. But the latest research suggests that people with Type 1 diabetes are also at risk. “When you look at all people with diabetes, either Type 1 or Type 2, the incidence of heart failure is four times higher than it is in the general population,” says Dr. Amgad Makaryus, a professor of cardiology at the Donald and Barbara Zucker School of Medicine at Hofstra/Northwell in New York.
The term “heart failure” refers to problems with the heart muscle’s ability to pump blood. These problems can deprive other parts of the body of sufficient oxygen and blood. They can also cause fluid buildup in the lungs, abdomen, and limbs. Heart failure can produce a wide range of symptoms, and it can also lead to organ damage or sudden death. Heart failure is not only more common in people with diabetes than in the general population, but it may be more deadly. A study of more than 36,000 people in the European Journal of Heart Failure found that median survival was reduced by more than a year among those who had both heart failure and Type 2 diabetes compared to those with heart failure alone.
Here, experts explain the connection between the two medical conditions. They detail the heart failure signs and symptoms to watch out for if you have diabetes, and the best available courses of treatment. They also offer advice for people with diabetes who want to lower their risks for heart failure.
The connection between heart failure and diabetes
Among people with diabetes, glucose (also known as blood sugar) does not move out of the blood and into the cells the way it should. This leads to elevations of both blood glucose and insulin, which is a hormone that helps clear the blood of glucose. These elevations may contribute to the development of heart failure in some people with diabetes. “Elevations in glucose levels and elevations in insulin levels can cause damage at a molecular level to cells of the heart,” Makaryus says.
But that’s far from the only connection between the two conditions. “Mechanistically, there are several processes that affect people with diabetes that raise their risk for heart failure,” says Dr. James Januzzi, a professor of medicine at Harvard Medical School and a clinical cardiologist at Massachusetts General Hospital. Januzzi says that, besides increasing risk for coronary artery disease, diabetes can cause direct injury to the heart muscle, resulting in stiffening and weakening that can culminate in heart failure. Research has linked diabetes to mitochondrial dysfunction, oxidative stress, inflammation, and an increase in the formation of harmful compounds called advanced glycation end products, or AGEs—all of which can contribute to the development of heart failure. “Diabetes is associated with a shift from glucose-related metabolism in the heart to the production of the sugar alcohol sorbitol, which may lead to cell death with scarring of the heart muscle,” Januzzi explains. “We also know that individuals with diabetes are at higher risk for chronic kidney disease, which is an independent risk factor for heart failure.” For all of these reasons, he says that the mere presence of diabetes is now considered a primary risk factor for heart failure.
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Signs and symptoms of heart failure
The symptoms of heart failure tend to be the same whether or not a person has diabetes. Fatigue lands at or near the top of the list, although at first this symptom may be subtle. “Someone may just feel like they don’t have the same energy they used to,” Januzzi says. Shortness of breath is another cardinal symptom of heart failure, but this may be difficult to spot if a person’s fatigue has caused them to cut down on physical activity. “Frequently I’ll ask a patient if they get shortness of breath and they’ll say no, but it’s because they’ve reduced their activity,” he says. As heart failure progresses, these symptoms tend to become much more noticeable. For example, shortness of breath can show up even after very mild physical activity, such as walking up a few stairs.
“Another classic sign is not just shortness of breath when you exercise, but shortness of breath when you’re lying down, or that wakes you from sleep,” says Makaryus. “This has to do with fluid overload in the lungs as a result of the heart not pumping the way it should.” Fluid overload can also lead to swelling (or edema) in the legs or abdomen of people with heart failure, he says.
While those are the most common symptoms, others include wheezing, weakness, a rapid or irregular heartbeat, nausea, weight gain, problems thinking or concentrating, and a persistent unexplained cough (that may or may not bring up white or pink mucous). As heart failure becomes more advanced, all these symptoms tend to be less subtle. “The fatigue may become so great that someone can’t complete their daily activities,” Makaryus says.
It’s important to note that many cases of heart failure pass through an early stage when there are no noticeable symptoms. However, at this stage the condition may already be detectable using certain blood tests. “We now have sensitive and specific biomarkers that can identify the earliest molecular changes in the heart that precede more overt structural change,” Pop-Busui says. There are drug therapies available that are proven to reduce the progression of heart failure, and catching the condition at this early, asymptomatic stage can help doctors improve outcomes for their patients. On the other hand, some diabetes medications can contribute to the development of heart failure. If the condition is caught early, someone with diabetes can get off these drugs before the condition progresses. “Early diagnosis can help make sure that people with diabetes have access to the best treatments at the right time,” Pop-Busui says.
Treatment options
The standard, first-line treatments for heart failure are medications, and experts say the drugs they choose are based on the severity of the condition. “We look at something called the ejection fraction, or the squeezing strength of the heart, to determine the appropriate treatment plan,” Januzzi says.
If a patient’s ejection fraction is reduced—meaning their heart is not pumping as strongly as it should—treatment usually includes several classes of drug that are designed to widen blood vessels and improve blood flow. “There are four main classes of therapy we recommend,” he says. These include beta blockers, aldosterone blockers, a medication called sacubitril/valsartan that widens blood vessels, and what’s known as an SGLT-2 inhibitor, which not only lowers blood pressure but also helps reduce blood glucose levels. (SGLT-2 inhibitors are often used to treat diabetes even absent heart failure.)
“For people with preserved ejection fraction, meaning anormal squeezing strength, therapeutic options are more limited,” Januzzi says. “However, recent clinical trials of SGLT-2 inhibitors showed benefit in these individuals, so these should be now considered in anyone with heart failure, but especially in people with diabetes.”
“In my opinion, these are very important drugs,” Makaryus says of SGLT-2 inhibitors. “Initially these were marketed as diabetes medications because they have blood sugar lowering effects, but clinical trials have found they improve outcomes and all-cause mortality from major cardiovascular events, including heart failure.” He says that another newer class of drug called GLP-1 agonists has also demonstrated benefit in people with both diabetes and heart failure, and is likely to be used more frequently to treat these co-occurring conditions.
The drugs used to treat heart failure in people with diabetes are often the same drugs prescribed for those without diabetes, but there’s evidence that they work even better in people with both conditions. “I tell my patients with diabetes they can expect even larger reductions in risk than someone without diabetes,” Januzzi says.
Apart from drugs, lifestyle and behavioral changes can make a meaningful difference for people with heart failure. “This includes increasing exercise whenever possible,” Januzzi says. “This also includes paying attention to one’s mood.” Depression and anxiety are both associated with poorer outcomes in people with heart failure, he says, so it’s necessary to address these mental health challenges (with therapy, for example) if they appear.
“Diet and weight loss are also critically important,” Januzzi says. “At our institution, we often recommend a Mediterranean-style diet that includes more complex carbohydrates and a judicious amount of protein.” While there’s a lot of strong research supporting the health benefits of Mediterranean-style diets, he notes that people with diabetes and heart failure should ideally work with a medical dietitian or nutritionist to create a custom eating plan. “Each individual patient has their own set of medical issues that might need to be considered,” he says. There’s no optimal, one-size-fits-all diet for people with diabetes and heart failure.
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Preventing heart failure
While everyone should prioritize heart health, taking steps to lower your risks for heart failure is especially important if you’ve been diagnosed with diabetes. “Even for those individuals with relatively new-onset diabetes, the condition may have been present for a while, and so the clock has already been ticking,” Januzzi says. “There’s no better time than now to focus on wellness.”
Controlling your risk factors for heart failure is step one, and that means not smoking, first and foremost, and also managing your cholesterol, blood pressure, and blood glucose through a combination of diet, exercise, weight loss, and medication therapy. “I also encourage my patients with diabetes to educate themselves so they understand their condition and the early warning signs of heart failure,” Januzzi says. Keeping yourself informed on the latest regarding your disease, your risk factors, your medication options, and your screening options is still a good idea. “I always advise my patients to be their own advocates,” he adds.
Heart failure is a common complication for people with diabetes. But with the right plan, you and your care team can take steps to effectively prevent or treat the condition.