Diabetes and heart disease

Diabetes increases your risk of heart disease and stroke. Learn what diabetes is, how it affects your heart, and what you can do to lower your risk.

What is diabetes?

Diabetes is a condition where there is too much glucose (a type of sugar) in your blood. It happens when your body has trouble making or using a hormone called insulin.

Insulin helps move glucose from your blood into your cells so it can be used for energy. When glucose stays in your blood instead of moving into your cells, it can build up and damage your blood vessels. This increases your risk of heart attack and stroke.

In New Zealand, it’s estimated about 320,000 people are living with diabetes.

Types of diabetes

There are three types of diabetes – type 1, type 2 and gestational diabetes – and a related condition called pre-diabetes.

Type 1 diabetes

Type 1 diabetes is an autoimmune condition where the immune system attacks the cells in your pancreas, the organ that makes insulin. This stops your body from making insulin.

Type 1 diabetes usually develops in children or young adults but can occur at any age. It can’t be prevented, symptoms can appear suddenly, and the exact cause isn’t fully understood, though it can run in families.

Type 2 diabetes

Type 2 diabetes is the most common type. It usually develops because your cells don’t respond well to insulin (insulin resistance). The pancreas makes more insulin to help, but over time, it can’t keep up. This causes blood sugar levels to rise.

Type 2 diabetes mainly affects adults, but the number of children with it is increasing. For many people, it can be prevented by being active, eating well and maintaining a healthy weight.

Gestational diabetes

Gestational diabetes develops during pregnancy. Hormones from the placenta make it harder for insulin to work, so your body needs two to three times more insulin than usual. If your pancreas can’t make enough to meet this demand, your blood sugar level rises.

Gestational diabetes usually goes away after the baby is born but increases the risk of both mother and baby developing heart disease or type 2 diabetes later in life.

Pre-diabetes

Pre-diabetes is when your blood sugar levels are higher than normal, but not high enough to be called type 2 diabetes. It shows that your body isn’t using insulin as well as it should.

Pre-diabetes increases your risk of type 2 diabetes and heart disease. For many people, it can be prevented by being active, eating well and maintaining a healthy weight.

More about diabetes

Maintaining a healthy weight

Diabetes and heart disease risk

If your diabetes isn’t well managed, it can damage your heart and blood vessels. As a result, people with diabetes are more likely to develop heart conditions, including increased risk of:

• coronary artery disease (also called ischaemic heart disease)
• heart attack and strokes
• heart failure
• atrial fibrillation.

People with diabetes also more likely to develop heart disease at a younger age.

Diabetes, coronary artery disease and heart attack risk

Over time, high blood sugar causes inflammation or damage to your arteries and the nerves that help control your heart and blood flow. It also changes how fats and other substances move in your blood, making it easier for plaque (fatty deposits) to build up in your arteries.

This makes your arteries narrower and stiffer and can reduce blood flow to the heart (coronary artery disease), which in turn makes you more likely to have a heart attack.

The risk of heart attack or stroke is two to four times higher in with people with diabetes, compared to those who don’t have it.

People with diabetes are more likely to have other risk factors, such as high blood pressure, high cholesterol and obesity, which further increases their risk of heart disease.

Diabetes and high blood pressure

Diabetes and high blood pressure are closely linked. Diabetes can damage your blood vessels and kidneys, both of which help control your blood pressure.

High blood pressure, in turn, can make insulin resistance worse and increase blood vessel damage. Having both conditions is common and doubles your risk of heart attack and stroke.

Diabetes and heart failure

Heart failure is a common complication of diabetes. A recent study suggested that approximately one in five people with diabetes will develop heart failure.

If you have diabetes, the best way to reduce your risk of getting heart failure is to keep your diabetes well managed.

Diabetes and atrial fibrillation

Diabetes increases your risk of developing the common heart rhythm condition atrial fibrillation (AF). Compared to those without diabetes, people with AF and diabetes are more likely to:

• experience more AF symptoms
• have more diabetes complications
• have a lower quality of life
• be hospitalised.

Other complications of diabetes

If diabetes isn’t well managed, over time it can damage your heart, blood vessels, nerves, kidneys, eyes, feet, skin and gums. This increases your risk of:

• heart disease and heart conditions (outlined above)
• kidney disease
• vision loss
• nerve damage and pain in your hands and feet
• amputation (removal of part of the foot or lower leg).

Your risk is higher if you also have high blood pressure, high cholesterol, are obese, or smoke.

Keeping your blood sugar and blood pressure levels within the healthy range and treating sores or infections early, can help reduce the likelihood of developing problems caused by diabetes.

Type 2 diabetes symptoms

Some people with type 2 diabetes don’t have any symptoms and may not know they have it. For others, symptoms can develop slowly over time, such as:

• feeling very thirsty
• needing to urinate (pee) a lot more than usual
• feeling very tired
• blurry vision
• sores or cuts that take a long time to heal
• skin or bladder (urinary tract) infections
• itching around the genitals or thrush (yeast infection).

How is diabetes diagnosed?

A blood test is used to diagnose diabetes. The most common test is an HbA1C. This test shows your average blood glucose level over two to three months.

Other blood tests include:

• a fasting blood glucose test (where you don’t eat for eight or more hours before you have the test)
• a random blood glucose test (taken at any time of day).

You may also be tested for your kidney function. While this doesn’t diagnose diabetes, it is monitored closely because kidney failure often happens because of diabetes. An initial test when you’re diagnosed gives your doctor a baseline record for the future.

During pregnancy, gestational diabetes can also be diagnosed with an oral glucose tolerance test. This involves blood tests before and after drinking a glucose drink to see how your body handles sugar.

Heart check for people with diabetes

A heart risk check (cardiovascular disease risk assessment) estimates your risk of heart attack or stroke in the next five years. To do this, your doctor or nurse will check your blood pressure, cholesterol, blood sugar and kidney health. They’ll also ask about your lifestyle, medicines and family history.

This check helps you and your healthcare team understand your heart health and what can be done to protect it.

For people with diabetes, it’s recommended this check be done every year to see if your risk has changed.

You can also try My Heart Check online, which estimates your heart attack risk and ‘heart age’. It includes tips to help improve your heart health and lower your risk.

How can I manage my diabetes and reduce my risk of heart disease?

Most people need a combination of medication and lifestyle changes to manage their diabetes.

Heart and diabetes medicines

It’s likely you’ll need medicines to treat your diabetes, and the other health conditions that are common with diabetes. These may include high blood pressure, heart conditions like atrial fibrillation and heart failure, and kidney problems.

The doctor will give you the medicines that are best for your conditions and are designed to provide the best health outcomes for you.

It is important to take these as prescribed to keep your blood sugar at a healthy level and to protect your heart.

Read more about diabetes medicines

Learn more about heart medicines

Here are some ways to manage your diabetes and reduce your risk of heart attack or stroke:

• Aim to eat healthy foods to help control your blood sugar levels.
• Plan ways to be physically active each day.
• Get good sleep each night, as poor sleep can affect your blood sugar, blood pressure and heart health.
• Keep your blood glucose and blood pressure within your target range.
• Take your medicines as prescribed.
• See your doctor or nurse at least once a year, or more often if needed.
• Make sure to have regular eye checks.
• Find a support group (see Diabetes New Zealand for groups near you).
• Ask whānau and friends to support you in managing your diabetes.
• Reach out to your healthcare team if you need help.

What else can I do to lower my risk of heart attack or stroke?

Making healthy changes to your lifestyle will help you lower your risk of heart attack or stroke and help control your diabetes. The more changes you make, the better the results.

• If you smoke, quit smoking.
• Be active most days.
• Eat and drink for a healthy heart.
• Reach a healthy weight.
• Find ways to manage stress.
• Take any heart medicines as prescribed.
• Manage other conditions like high blood pressure and high cholesterol.

Other heart disease risk factors