How Do I Know if I Have Diabetes Complications?

Medically Reviewed by Michael Dansinger, MD on May 14, 2021

If you have diabetes, it's important to watch out for complications that can cause problems in your feet, eyes, kidneys, and other spots in your body. Your doctor may suggest tests that can show if you've got signs of conditions like neuropathy, diabetic eye disease, or kidney damage. An early diagnosis can help you keep these troubles under control.

A1c Blood Test

Most diabetes complications are linked to blood sugar levels that are too high or too low. An A1c blood test is a key way to check that your blood sugar levels aren't out of whack.

Until your blood sugar levels are stable, your doctor may do an A1c test four times a year. From then on, you'll get tested twice a year.

Your doctor will take a sample of blood from your arm or finger to measure your average blood sugar (glucose) levels over the past 3 months.

If you take insulin or have blood sugar levels that are out of control, your doctor may also recommend that you test yourself at home as often as several times every day. You'll prick your finger and place a drop of blood on a disposable test strip that feeds into a portable blood glucose meter.

Cholesterol and Blood Pressure Tests

At each appointment, your doctor will keep an eye out for things that raise your odds of heart disease, which has been linked to diabetes.

They'll take your blood pressure by placing a cuff around your upper arm that tightens to read the flow of blood through your arteries. They'll also take a small blood sample from your arm to check levels of LDL cholesterol and triglycerides.

Foot Exams

High blood sugar levels can lead to peripheral diabetic neuropathy -- nerve damage that causes pain or loss of feeling in your legs and arms. This can bring on sores in your feet that can sometimes get infected.

Diabetes can also lower circulation to your feet, which makes it harder for infections to heal.

To check for these problems, at least once a year your doctor will thoroughly examine your feet. They'll either tap on them with a tool similar to a nylon hairbrush bristle or prick your feet with a small needle. If you don't feel it, you may have nerve damage.

If you're diagnosed with peripheral diabetic neuropathy, you'll need thorough foot exams at every doctor's visit. You'll also need to check your feet yourself every day for cuts, sores, and blisters.

Eye Exams

High blood sugar levels can damage parts of your eye such as your retina, lens, optic nerve, and vitreous gel. Known as diabetic eye disease, it's a complication that can lead to vision problems and permanent vision loss.

To test for signs of eye damage, you'll get a dilated eye exam when you're first diagnosed with diabetes and every 1 to 2 years after that.

For this test, your doctor puts drops into your eyes that temporarily make their pupils get bigger. Then they use a special magnifying lens to check your retina and optic nerves. They'll also test your eye pressure, side vision, and distance vision.

The test is painless. But since you'll be sensitive to light and your vision will remain blurry for a few hours, it's a good idea to bring sunglasses and get someone to drive you home.

Kidney Disease Tests

About one in four people with diabetes has kidney disease. To check for signs that your kidneys aren't working right, you'll probably get a blood and a urine test once a year. You may need to be tested more often if you're likely to get kidney disease because of high blood pressure, heart disease, or a family history of kidney failure.

Your doctor will check a sample of your urine for albumin, a blood protein that can end up in your pee if your kidneys are damaged.

They'll also take a sample of your blood to check your glomerular filtration rate (GFR), a measure of how well your kidneys are doing their job of filtering waste in your blood.

Tooth and Gum Exams

Diabetes dries out your mouth and can increase the sugar in your saliva. Both encourage plaque (bad bacteria) growth on your teeth.

Over time, untreated plaque can lead to tooth decay, gum disease (gingivitis), periodontitis, and tooth loss. So keep an eye out for signs of gum problems, including swollen, tender, or bleeding gums. And see your dentist twice a year for a cleaning and checkup.

Diabetic Ketoacidosis (DKA) Urine Test

When your cells don't get enough glucose, they start to burn fat for energy, which makes substances called ketones. High ketone levels signal that your diabetes is out of control or that you're getting sick. This can lead to diabetic ketoacidosis (DKA), a potentially life-threatening diabetes complication.

Your doctor may suggest you take a sample of your urine at home and check ketone levels with a special test strip if:

  • Your blood sugar levels are high (usually over 240 mg/dl)
  • You're sick
  • You have signs of DKA, including dry mouth and frequent need to pee

Thyroid Tests

Diabetes is linked to a condition called hypothyroidism. When you have it, your thyroid gland doesn't make enough of the hormones that control your metabolism.

To check for this, about once every 5 years your doctor will take a sample of your blood to test your thyroid hormone levels.

You may get tested every 1 to 2 years if you have a higher chance of getting hypothyroidism because you're a woman over 40 or you have a family history of thyroid disease.

Gastrointestinal System Tests

Gastroparesis is a diabetes complication caused by high levels of blood sugar over a long period of time. Your doctor may recommend tests if you get symptoms like feeling full after eating a small amount of food or vomiting undigested food.

You may need one or more of these tests:

  • Upper gastrointestinal endoscopy
  • Upper GI series
  • Gastric emptying scintigraphy
  • SmartPill
  • Gastric emptying breath test

These tests mostly involve eating or drinking a substance or getting an imaging test (like an X-ray) to help doctors check if your digestive system is working well.

WebMD Medical Reference



American Academy of Ophthalmology: "What to Expect When Your Eyes Are Dilated."

American Diabetes Association: "Checking Your Blood Glucose," "Diabetes Complications," "DKA (Ketoacidosis) & Ketones," "Gastroparesis."

Diabetes New Zealand: "Diabetes and Your Thyroid."

Duntas, L. Clinical Endocrinology, February 2011.

Mayo Clinic: "Diabetic Hypoglycemia."

National Institutes of Health: "Diabetes, Gum Disease, & Other Dental Problems," "Diabetes, Heart Disease & Stroke," "Diabetic Eye Disease," "Diabetic Kidney Disease," "Low Blood Glucose (Hypoglycemia)," "Nerve Damage (Diabetic Neuropathies)," "Preventing Diabetes Problems,"

"The A1C Test & Diabetes."

FDA: "Blood Glucose Monitoring Devices."

UpToDate: "Patient Education: Preventing Complications in Diabetes Mellitus."

Wang, C. Journal of Diabetes Research, April 2013.

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