How do I know if I have diabetes?

Matthew J. Freeby, MD
Endocrinology Diabetes & Metabolism
To find out if you have diabetes, see your doctor and consider screening if you are at high risk. Diabetes is diagnosed by blood testing. Most doctors use a hemoglobin A1C, fasting glucose or an oral glucose tolerance test.
For some people with only modest elevations in glucose, diabetes may be silent. For others with elevated glucose levels, symptoms may be present. Risk factors and typical symptoms can include:
  • a family history of diabetes
  • being overweight
  • being in a high-risk ethnicity
  • increased thirst
  • increased urination
  • unintentional weight loss
Ronald Tamler, MD
Endocrinology Diabetes & Metabolism
If you've just been diagnosed with diabetes, you need to know the kind of diabetes that you have. In this video, Ronald Tamler, MD, clinical director of the Mount Sinai Diabetes Center, explains why this diagnoses is important.
The amount of glucose (sugar) in your blood varies throughout the day, but it should always stay within a certain range. If your blood glucose is above the normal range, you may have diabetes or you may be at higher risk for it. Diabetes is a disease that causes your blood glucose to be too high. It can damage your blood vessels and increase your risk for heart attack, stroke, and other health problems.

To check for diabetes -- or prediabetes, a condition that often leads to diabetes -- you should have a fasting blood glucose test. This test checks your blood sugar when you haven't eaten anything for at least 8 hours, usually overnight. You might also have a blood test called HbA1c, a single test that can measure your average blood glucose over a period of several weeks.

If your blood glucose is above the normal range based on either test, you should see a doctor. Medication -- along with a meal plan, regular exercise, and other healthy habits -- can help you manage your blood glucose and prevent further problems.
Your doctor can diagnose diabetes by doing tests to measure the levels of sugar (glucose) in your blood. You might also experience symptoms of diabetes, including excessive thirst, frequent urination, increased hunger, and fatigue. There are several types of diabetes, but the most common are type 1, type 2 and gestational diabetes (which develops during pregnancy).
You may not know you have diabetes for many years. But taking a test such as the fasting plasma glucose screening, which measures your blood sugar level, will provide you with valuable insight. This is a simple finger-stick blood screening to measure blood sugar levels following 8 hours of fasting.
William Lee Dubois
Endocrinology Diabetes & Metabolism

OK, so the most common kind diabetes is sneaky. It creeps up on you like a thief in the night. Actually, it’s slower, so maybe I should say it stalks you like a wolf in the dark. It can take years. But you can’t feel diabetes developing because diabetes has no symptoms.

But once your diabetes is advanced enough to make your blood sugar very high you’ll notice changes. You might find yourself thirsty. A lot. And you’ll pee. A lot. In fact, you’ll probably get up several times a night to pee. And of course you’ll tell yourself it’s just because you are drinking a lot because you’ve been so thirsty, so it won’t occur to you to call your doctor.

And you’ll find yourself low on energy. Of course you’ll tell yourself that you’re not getting enough sleep because you are getting up to pee four times a night because you’ve been so thirsty, so it won’t occur to you to call your doctor.

And you might find that your vision is getting….you know… kinda fuzzish sometimes. You tell yourself that you should get your eyes checked. Maybe next month.

Thirst. Frequent urination. Low energy. Blurry vision. These are the classic symptoms of hyperglycemia, or high blood sugar. Because they creep up a little at a time and get worse very slowly they are not alarming the way something like, oh… I don’t know… chest pain is.

Another symptom of high blood sugar that I didn’t mention is extreme irritability. The reason I didn’t mention it is because you’ll be the last to notice. But if you are suffering all the other symptoms on the list, ask your loved ones if you’ve been testy lately.

Of course those are just the warning signs. To really know, you need to get tested. The current state of the art is a six minute test on a single drop of blood from your fingertip that most clinics and many doctor’s offices can do in-house.

One last note. If you do have diabetes I actually have good news. (Who’d thought having diabetes and good news could go in the same sentence?) Once you are treated all of these symptoms will melt away. Your thirst will dissolve. You’ll sleep through the night. You’ll feel ten years younger. You’ll see clearly. And your loved ones will want to spend time with you again.

Doctors can use the fasting plasma glucose test (FPG), the oral glucose tolerance test (OGTT), or the A1C test to detect prediabetes. Both the FPG and OGTT require a person to fast overnight. In the FPG test, a person's blood glucose is measured first thing in the morning before eating. In the OGTT, a person's blood glucose is checked after fasting and again 2 hours after drinking a glucose-rich drink. The A1C test can be performed at any time since its result is an average of your blood glucose over the past 2-3 months.

Continue Learning about Diabetes


Diabetes mellitus (MEL-ih-tus), often referred to as diabetes, is characterized by high blood glucose (sugar) levels that result from the body’s inability to produce enough insulin and/or effectively utilize the insulin. Diabetes ...

is a serious, life-long condition and the sixth leading cause of death in the United States. Diabetes is a disorder of metabolism (the body's way of digesting food and converting it into energy). There are three forms of diabetes. Type 1 diabetes is an autoimmune disease that accounts for five- to 10-percent of all diagnosed cases of diabetes. Type 2 diabetes may account for 90- to 95-percent of all diagnosed cases. The third type of diabetes occurs in pregnancy and is referred to as gestational diabetes. Left untreated, gestational diabetes can cause health issues for pregnant women and their babies. People with diabetes can take preventive steps to control this disease and decrease the risk of further complications.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.