Diabetes, an epidemic that is sweeping the world, has been linked to increased risk of heart failure in a global study of 12 million people.
The risk is particularly high for women, and is greater for type 1 diabetes than type 2.
Toshiaki Ohkuma, from the George Institute for Global Health in Australia, says it was known that women with diabetes have higher risk of heart disease and stroke than men, but whether diabetes confers the same high risk for heart failure (an inability to pump enough blood to meet the body’s needs) was unclear.
To find out, he and colleagues from Australia, Japan and the UK pooled data from 47 population-based studies over 50 years from 10 countries, including the US, Canada, Australia, and European and Asian nations.
They only included research with men and women, omitting single-sex studies that may have provided unreliable results in the past.
The results, published in the journal Diabetologia, show that women with type 1 diabetes have a more than five-times greater risk of heart failure than those without. In men the risk is 3.5 times higher.
Type 2 diabetes conferred a lower risk overall, but in women was still nearly double that of those without diabetes (95% higher), while men had a 74% greater risk.
Globally, the number of people with diabetes has almost quadrupled since 1980, now affecting around 422 million people. This is estimated to reach 642 million by 2040.
The most common form – type 2 – is related to lifestyle factors such as unhealthy diet, low physical activity, excess weight and smoking.
Type 1, on the other hand, is one of more than 80 different autoimmune diseases in which the immune system attacks its own organs. The cause and treatment of these diseases is currently unknown, although they have been associated with “leaky gut” and stress.
Diabetes already affects women disproportionately. Why they are also at greater risk of developing heart failure is unclear.
Co-author Sanne Peters, from the George Institute for Global Health in the UK, suggests several possible reasons.
“Women were reported to have two years’ longer duration of prediabetes than men and this increased duration may be associated with greater excess risk of heart failure in women,” she says.
“Some major concerns are that women are also being undertreated for diabetes, are not taking the same levels of medications as men and are less likely to receive intensive care.”
The International Diabetes Foundation flags socioeconomic inequalities that lead to poor diet, low physical activity and limited access to health services, especially in developing countries.
Ohkuma says the study “highlights the importance of intensive prevention and treatment of diabetes in women”.
“Further research is required to understand the mechanisms underpinning the excess risk of heart failure conferred by diabetes (particularly type 1) in women,” he adds, “and to reduce the burden associated with diabetes in both sexes.”