The idiosyncratic female diabetic heart

Diabetic women are more likely to die from heart problems than diabetic men are. This is a deeply personal issue for me, as my mother has lived with diabetes for over 20 years, following her last pregnancy. It means a lot to me to be able to contribute to the growing body of research on sex-specific health issues.

Diabetes is a chronic metabolic disorder characterised by high blood glucose levels because of inadequate insulin production or insulin resistance. Insulin is a hormone produced by the pancreas that helps regulate blood glucose levels. If left uncontrolled, diabetes can lead to several serious health complications, including cardiovascular disease, which is the most common comorbidity of diabetes.

Type 2 diabetes remains the fastest-growing long-term disease condition in New Zealand, with a prevalence of 5.5 percent. The number of New Zealanders diagnosed with diabetes has doubled over the past 10 years and is projected to double again over the next 20 years. In New Zealand, cardiovascular disease is the leading cause of death, accounting for 40 percent of all deaths annually. Compared with healthy subjects, diabetic patients are three times more likely to develop heart failure and have twice the rates of cardiovascular mortality and sudden cardiac death.

These risks of diabetes on the heart are sex‑dependent. There are several factors that contribute to the increased risk. Compared with men with diabetes, women with diabetes have a two‑fold higher risk of developing coronary heart disease. Not only are women more likely to have heart attacks earlier than men, but also, they are more likely than men to die as a result.

Possible explanations have included poorer clinical care for women, which is one instance of inequity in healthcare between Māori and non-Māori. The reduction of such inequities is one of the main intentions of the New Zealand Health Strategy.

Yet much of the research on the diabetic heart has been focused on the male heart. My own research, funded by the Heart Foundation postgraduate scholarship, is focused on the diabetic female heart because it is relatively more vulnerable. We need to understand why.

A better life for diabetic women can be achieved by answering two interlinking research questions. Why does diabetes confer enhanced risks on the female heart? And what cellular mechanisms could explain dysfunctions in mechanics and energetics?

Using a combination of approaches, including energetic experiments, imaging analysis and mathematical modelling, I will investigate why Type 2 diabetes confers sex‑dependent effects on how well the heart muscles perform, how this affects the energy flow through the heart.

Energy will be quantified as the heat liberated during muscle contraction using the world’s only work‑loop calorimeter. This is a device developed by the Auckland Bioengineering Institute (ABI) for measuring the properties of realistically contracting heart muscles. .

My overall hypothesis is that the diabetic female heart has much-reduced energy efficiency, arising from disturbed energy associated with sub-cellular (within the cell) processes. Essentially, we are trying to understand how diabetes impacts the heart's ability to function properly, and why women with diabetes are more likely to experience heart problems.

The higher risk for heart problems in diabetic women may be due to biological differences. Research has shown that diabetic women can experience more diastolic (the relaxation phase of the heartbeat) dysfunction and have a worse cardiometabolic profile (cardiac health assessment) compared to diabetic men.

However, recent studies have also shown there may be sex-specific differences in how diabetes affects the heart's energy metabolism. Women with diabetes may have trouble with the proteins involved in making the heartbeat, which can make them less efficient at producing energy. But we still need more research to fully understand how diabetes affects men and women differently.

My research is just one small part of a larger effort to address the gender disparities that still exist in healthcare. But it is a mission that is deeply personal to me. As the daughter of a diabetic mother, I believe we can build a world where all women like my mother, regardless of their health status, have a better chance to live healthy, fulfilling lives.