01:15 - Source: CNN
Diabetes is on the rise
CNN —  

Doctors have long known about a link between diabetes and an increased risk of heart failure, but a new paper suggests the link is significantly stronger in women than in men.

Type 1 diabetes was associated with a 47% increased risk of heart failure in women compared with men, and type 2 diabetes was associated with a 9% increased risk, according to the paper, published in the journal Diabetologia on Thursday. The reason for the difference in risk between type 1 and type 2 remains unclear.

In general, “once women have diabetes, they have a much higher risk of heart failure than women without diabetes,” said Sanne Peters, a research fellow at the George Institute for Global Health at the University of Oxford in the United Kingdom, who was an author of the paper.

The paper sheds light on how it remains important to prevent the development of type 2 diabetes, in particular, since it can be a risk factor for heart failure and other health problems.

More than 30 million people in the United States, or about one in 10, have diabetes and up to 95% of them have type 2 diabetes, according to the US Centers for Disease Control and Prevention. Globally, the number of people with diabetes has risen from 108 million in 1980 to 422 million in 2014, according to the World Health Organization.

“The bottom line really comes down to that people should have a healthy lifestyle, so eat healthfully and exercise a lot,” Peters said. “It’s important to maintain a healthy weight.”

The new paper reviewed 14 previously published studies that focused on the association between diabetes and heart failure risk. Those studies were published between January 1966 and November 2018.

After reviewing and analyzing the data in those studies – which included 12 million people and 253,260 cases of heart failure – the researchers noticed that both type 1 and type 2 diabetes were stronger risk factors for heart failure in women than in men.

“We don’t know exactly why but there’s a couple of possible mechanisms that we are currently investigating further,” Peters said.

For instance, diabetes is also a stronger risk factor for coronary heart disease in women than men – a cause of heart failure – which possibly could drive the difference found in the paper.

Historically, women have been undertreated for diabetic heart disease compared to men, which subsequently could lead to a stronger association of diabetes with heart failure in women than in men.

The researchers also noted in the paper that women have a low absolute risk for heart failure compared to men, which mathematically could be driving the difference.

Overall, more research is needed to explain the reason for the difference found between men and women.

The paper also had some other limitations, including that the data was limited to what was found in those previously published studies and did not include information on the duration of each person’s diabetes.

“We do know that people with diabetes have an increased risk of heart failure. That is well known, but it’s under-appreciated in the general medical community, and obviously as well as in the lay community,” said Dr. Fernando Ovalle, director of the University of Alabama at Birmingham’s Division of Endocrinology Diabetes and Metabolism, who was not involved in the report.

“What this points out is that it’s not just there, and it’s large, but most importantly two things: It seems to be stronger in type 1 than in type 2, and stronger in women than in men,” he said about the paper.

It serves as an important reminder for all people with diabetes – especially women – to pay close attention to their health, he added.

“It makes us reflect,” Ovalle said.

Diabetes patients should try to do everything they can to lower their heart failure risk, including not smoking, controlling cholesterol, taking a statin, controlling blood pressure, and also controlling blood glucose, he said. “If you’re a woman and you have diabetes, please don’t smoke because that combination is just deadly.”

The paper’s findings support what physicians treating diabetes patients have long believed, said Dr. E. Dale Abel, chairman of the Department of Internal Medicine and director of the Fraternal Order of Eagles Diabetes Research Center at the University of Iowa in Iowa City, who was not involved in the report.

Get CNN Health's weekly newsletter

Sign up here to get The Results Are In with Dr. Sanjay Gupta every Tuesday from the CNN Health team.

“The bigger question is, why does this occur?” Abel said.

“Their study doesn’t answer that question as to why women are at greater risk of heart failure in diabetes, but I do think that the implication of this – certainly for women and also for people who take care of diabetic women – is that they should really have a low index of suspicion for at least asking patients about symptoms that could be consistent with heart failure,” he said. “Both practitioners as well as women with diabetes should certainly be on the lookout for heart failure-type symptoms.”