High A1C Levels? Why You May Need an EKG or Echocardiogram

You need a certain amount of sugar (glucose) in the blood to fuel all the cells of the body. But  blood glucose can start to cause problems when it gets too high. To get an idea of your average blood glucose level over the past 2 to 3 months, your provider will check your hemoglobin A1C (HbA1C or A1C).

This test measures the amount of glucose that gets stuck to a protein in your blood cells (hemoglobin). A high A1C level means you have an abnormally high level of glucose in your blood. If the A1C is too high for a long period of time, it can cause glucose to get stuck to other cells in your body and eventually cause serious problems.

What happens if your A1C is too high?

If your A1C is above 5.7, you may be diagnosed with prediabetes. If it gets above 6.5, you’re getting into the range of diabetes. At these levels, glucose is not just sticking to your hemoglobin, it’s starting to stick to other cell types, too. 

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An A1C level above 5.7 can lead to damage to your nerves, eyes, and even your heart. Some of the complications of an A1C level that’s high over the long term are the same as those in diabetes. These complications include:

• Retinopathy: The small blood vessels in the eyes can become damaged and lead to blindness.

• Neuropathy: High glucose over a long period of time can damage the nerves. You may feel this as numbness, tingling, or pain — especially in the feet.

• Chronic kidney disease: If high levels of glucose damage the blood vessels in the kidney, they can no longer work properly. This can lead to kidney failure and the need for dialysis.

• Stroke: The brain depends on a healthy blood supply for oxygen and nutrients. If the vessels to the brain are damaged, the blood supply can be cut off. This can lead to a stroke.

• Heart attack: The heart also relies on tiny blood vessels to function properly. If the arteries to the heart are blocked, you can have a heart attack.

Why monitor your heart health if you have a high A1C?

Heart disease is the leading cause of death in the U.S. In many cases, you can prevent a heart attack if you catch heart disease early enough. 

A high A1C level results in higher rates of heart disease. But there are treatment and lifestyle options to help reduce your A1C. The sooner you’re aware of it, the better.

What are the heart screening tests for people with a high A1C?

The heart screening tests for people with a high A1C are the same ones healthcare providers use for routine heart screening. If your A1C is high, you may need to do these tests at an earlier age or more often than other people. If any of these tests show that your heart isn’t working the way it should, your provider will likely refer you to a cardiologist.

Healthcare providers use many tests to check heart function. Here are four of the most common tests.

1. Electrocardiogram (ECG/EKG)

An electrocardiogram (EKG or ECG) test is a safe and painless test that measures the electrical signals of your heart beat. An EKG shows if your heart is beating at a normal rate, rhythm, and strength. 

An EKG can also show:

• Heart enlargement

• Signs of heart inflammation

• Prior heart damage

• Signs of a heart attack  

2. Coronary angiogram

During an angiogram or a cardiac catheterization, a healthcare provider places a small catheter into a blood vessel in your arm or groin. They’ll pass a tiny tube through the arteries of your heart and take X-rays. This allows the specialist to see any narrowing or blockage within the arteries of your heart.

3. Echocardiogram

An echocardiogram (echo) is a safe and painless test that uses sound waves to create moving pictures of your heart. The pictures show the size and shape of your heart and how well your heart is pumping blood. 

A Doppler ultrasound is a type of echo that shows how well blood flows through the heart’s chambers and valves. You may have the echocardiography in your provider’s office or at a hospital. You won’t need to do anything in advance to prepare for most types of echo.

4. Stress test

A stress test (treadmill or exercise) shows how well your heart is able to handle the stress of its workload. During this test you walk on a treadmill while you have monitors on your chest. As the treadmill speeds up, your body has to work harder. This means your heart has to pump more blood and beat faster. The monitors can detect if there’s enough blood flow through the arteries to your heart muscle.

Sometimes, instead of actually exercising, your provider will inject a medication that mimics the effects of exercise. This is a pharmacologic stress test. Providers often recommend this if you can’t tolerate walking on a treadmill or if you have known heart abnormalities.

Your cardiologist might inject a small amount of radioactive dye and take X-rays during your stress test (nuclear stress test). This provides more insight on the blood flow to the heart. Or they might do an echocardiogram (stress echocardiogram) as a part of your stress test. This provides more information about the pumping action of your heart.

How can you prevent heart disease if you have high A1C levels?

If you have an elevated A1C, the best way to prevent heart disease is to work on lowering your A1C. Since high blood glucose levels cause an increase in A1C, you’ll need to start by getting your blood sugar down. There are several ways to reduce blood sugar and A1C for better heart health.

Diet

Your healthcare provider will likely suggest that you follow a heart-healthy diet. This will include more unprocessed, whole foods like fruit and vegetables. A heart-healthy diet will also avoid fried foods and processed or fatty meats. 

Studies show the Mediterranean diet reduces A1C levels in people who stick with it. This eating plan focuses on seafood, fruits, vegetables, and healthy fats.

Exercise

Exercise can also improve heart health and lower your A1C. It can also reduce the risk of diabetes. Walking is a great way to start exercising. If you aren’t already exercising, talk with your healthcare provider about how you can safely get moving. 

Lower your cholesterol

If you have a high A1C, you’re also more likely to have high cholesterol. In addition to high blood sugar and a high A1C, high cholesterol is also a risk factor for heart disease. 

To lower your cholesterol, you’ll often need to make dietary and lifestyle changes. The Mediterranean diet is also helpful for lowering cholesterol. Exercise can help here, too. If diet and exercise aren’t enough, you might need to consider medications. 

There are many medications to help lower cholesterol. Your healthcare provider can help you decide which is best for you.

Medications

Medications may be necessary to help reduce A1C, especially if it’s very high or doesn’t improve with diet and exercise. Many different medications lower A1C. Some of the most common ones include:

• Metformin: This medication reduces how much glucose your liver makes and improves how well your body responds to insulin. It can lower your A1C by 1%.

• Sulfonylureas: This group of medications (like glucotrol) causes your pancreas to release more insulin. Insulin causes your cells to absorb glucose so that it’s not too high in the blood. They also lower A1C by about 1.5%

• Thiazolidinediones: These medications (like Actos) reduce the amount of glucose your liver makes and improve insulin sensitivity. They improve A1C by 1%.

• Sodium-glucose cotransporter 2 (SGLT2) inhibitors: SGLT2 inhibitors (like Farxiga) cause the kidneys to dump excess glucose into the urine. These medications reduce A1C by just under 1%.

• Dipeptidyl peptidase-4 (DDP-4) inhibitors: DDP-4 inhibitors (like Januvia) prevent the breakdown of a hormone (GLP-1). GLP-1 helps your pancreas release insulin and also slows down the liver’s production of glucose. DDP-4 inhibitors help reduce A1C by less than 1%.

Why trust our experts?

Written by:

Frank Schwalbe, MD

Frank Schwalbe, MD, is an assistant professor of anesthesiology at the Yale School of Medicine. He has practiced anesthesiology for 30 years.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

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