A guide to diabetes and your heart

How exactly does diabetes affect the heart? And what can you do to reduce your risk of heart failure and stroke if you have diabetes? We asked internationally renowned cardiologist Professor Kausik Ray, specialist in cardiovascular disease prevention and diabetic heart disease.

How does diabetes actually affect the heart?

Diabetes can affect the heart in a number of different ways. The most common process is the narrowing of the blood vessels over time, where fat lines the blood vessels increasingly with duration of diabetes. That in turn increases the risk of heart disease and strokes.

In addition to that, the effect of diabetes on the heart can affect the heart muscle directly whereby the heart muscle becomes stiff, and it doesn't relax as well, leading to heart failure.

So the potential complications of diabetes are heart attacks, strokes and heart failure.

How are heart problems diagnosed in diabetes patients?

Well, one of the challenges in people with diabetes is that the pain threshold is a lot different in people with diabetes.

Often typically when somebody's having a heart attack, they express chest pain, sweating, discomfort, and if you've had diabetes for a long time, patients actually don't get the same feelings of pain. So often, heart disease is more silent. Therefore, you need to have a high threshold for diagnosis.

If people with diabetes have slightly atypical symptoms – perhaps they start to get breathless on walking – that could be a sign that there's a problem with the blood supply to the heart, or that the heart muscle is not pumping adequately. Heart failure is undiagnosed in about 25% of people with diabetes.

We have a few ways to diagnose heart problems in diabetic patients. We can take scans of the heart or do some blood tests to check if the heart is being overworked and is stressed. In people with slightly atypical symptoms, we can do a stress test on a treadmill or a bicycle, where by increasing the heart rate, you can take images of the heart muscle to see if it's pumping properly in response to exercise.

Do heart problems in diabetic patients have to be treated differently?

No - heart problems in patients with diabetes are treated with the same medications as in people without diabetes.

So that basically means people with diabetes need cholesterol-lowering medications. We know that for one unit lowering in so-called bad cholesterol or LDL, the patient with diabetes get about a 22% reduction in risk.

But often even when you've lowered blood pressure, you've lowered cholesterol, you might often use things like aspirin. This is obviously on top of things like lifestyle changes.

That being said, having diabetes gives you a so-called “high residual risk”. This means often you have to treat those much, much more aggressively in people with diabetes. Part of this involves addressing kidney problems. Once kidney problems start, that often increases the likelihood of heart failure, so kidney disease needs to be treated much earlier, particularly when detected early.

How can I avoid heart disease if I have diabetes?

The issue with diabetes is the on average if you have diabetes you double the risk of heart disease throughout your life. And the earlier somebody develops diabetes the more life years you lose.

So on average, a 40-year-old with diabetes loses about 6 years of life. Half of those are going to be from heart disease or strokes. If you’re age 16 you've already got diabetes and have had heart disease, on average the number of life years lost is about 12.

In order to claw back those years, you have to modify your lifestyle and think about medications that traditionally reduce the risk of diabetes progression or complications. So that means lowering your cholesterol, it means controlling blood sugars, it means controlling blood pressure and doing that early before complications develop.

The main take-home message for people with diabetes is that prevention needs to start early, it needs to be long-term, and it needs to involve an aggressive control of risk factors, maintaining that through life.