3 Diabetes Tests You Must Have

Even before you notice symptoms, high blood sugar can damage parts of your body. That's why certain diabetes tests to check blood sugar control and to catch problems early are so crucial.

But many patients aren't getting key diabetes tests at least annually, such as the hemoglobin A1c test, a dilated eye exam, and a foot exam.

"If you look at the nationwide data, it's sobering," says Enrico Cagliero, MD, a diabetes researcher and assistant professor of medicine at Harvard Medical School. "A lot of diabetic patients are missing essential checks."

"People with diabetes should know that complications aren't inevitable," Cagliero says. "Unfortunately, we still see a lot of complications, and a lot of those could have been prevented. It's absolutely essential to get into this preventive mode as soon as possible. It definitely pays down the road."

Don't miss these diabetes tests.

Diabetes Test #1: Hemoglobin A1c

This diabetes blood test, also called HbA1c, tells you and your doctor how well diabetes is managed over time. It measures your average blood sugar in the previous three months to see if it has stayed within a target range.

Here's how this test works. Your red blood cells contain hemoglobin, which allows cells to transport oxygen to tissues. As a cell ages, the hemoglobin becomes increasingly "glycated," meaning that more glucose molecules stick to it. Higher glucose levels in the blood mean higher glycated hemoglobin, which translates into a greater HbA1c reading.

• Normal HbA1c is 5% or less.
• An HbA1c value above 7% means diabetes is poorly controlled. People with diabetes should aim for an HbA1c value below 7%.

You don't need to fast or prepare for an HbA1c test. Ask your doctor how often you need to be tested. Doctors usually recommend every 3 to 6 months.

Keeping blood sugar under control has been proven to reduce risk of complications. In the landmark, 10-year Diabetes Control and Complications Trial (DCCT), researchers studied how careful blood sugar control affected the rate of complications from type 1 diabetes. Among 1,441 subjects, those who received intensive treatment to achieve tight blood sugar control had an average HbA1c of about 7%, while those on standard therapy averaged about 9%. The group with tight control had much lower risk of complications:

• 76% reduced risk of eye disease
• 50% reduced risk of kidney disease
• 60% reduced risk of nerve disease

Diabetes Test #2: Dilated Eye Exam

If you have diabetes, your ophthalmologist or optometrist should perform a dilated eye exam, in which the pupils are widened with drops, to check for signs of diabetic retinopathy.

With diabetes, high blood sugar damages tiny blood vessels in the retina, the light-sensitive tissue at the back of your eye. In a more advanced form called proliferative retinopathy, new blood vessels grow along the retina and in the clear, gel-like vitreous that fills the inside of the eye. Without treatment, these new vessels can bleed, blur vision, severely damage the retina, and lead to vision impairment or blindness.