How to Test for Diabetes

Learn the early warning signs of type 2 diabetes and which tests you’ll be given.

What is type 2 diabetes?

Diabetes is a disease that causes high blood sugar levels. As we get older, our risk of developing type 2 diabetes increases. More than 1 in 4 adults ages 65 and older have type 2 diabetes. And about half of older adults have pre-diabetes, which means they are at high risk for developing type 2 diabetes.

That’s why it’s important to recognize the symptoms of diabetes. So you can get the recommended tests to help you diagnose and manage diabetes in its early stages. By managing your blood sugar (glucose) levels, you may prevent serious complications, such as cardiovascular disease, nerve damage, and foot and eye problems.

Who should be tested for diabetes?

Pro Tip

21% of all adults with diabetes are not aware they have the condition, which can lead to more complications. —Dr. Anis Rehman

If you develop any of the following symptoms, ask to be tested for type 2 diabetes. In type 1 diabetes, which is typically diagnosed in children and young adults, the body doesn’t produce any insulin. (Insulin is the hormone that shuttles glucose into muscles to be used as energy.)

In type 2, which tends to develop over time, the body produces less insulin and doesn’t use it as effectively.

Diabetes symptoms

  • Thirstier than normal
  • Increased urination
  • Increased hunger and/or unexplained weight loss
  • Fatigue
  • Blurred vision
  • Numbness or tingling in the feet or hands
  • Sores that do not heal

If you’re 45 or older, you should have annual screening tests for type 2 diabetes according to the American Diabetes Association. Screening is also recommended for younger adults who are overweight or obese and have one other risk factor for type 2 diabetes, such as high blood pressure, a family history of diabetes, or physically inactive. Women who had gestational diabetes during pregnancy should also be screened annually.

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How does a doctor diagnose diabetes?

There are four main blood tests for diagnosing diabetes. For all of these tests, if someone has a positive test with symptoms, diagnosis of type 2 diabetes is made. However, for those without symptoms, your doctor may need to do a second test from the list to confirm the diagnosis.

Fasting plasma glucose test: This blood test measures your blood glucose (sugar) levels at the time of the test. It’s taken after fasting for 8 hours and often done as part of your yearly physical.

  • What the test results mean: Normal levels are 99 mg/dL and below, prediabetes is 100 to 125 mg/dL, diabetes is 126 mg/dL and above.

Glycated hemoglobin (A1C) Test: The A1C test provides an average glucose level based on the past two to three months. Because it doesn’t require fasting, it is a more popular test.

A1C measures the amount of glucose that attaches to hemoglobin, the part of the red blood cell that carries oxygen. It is the main test people who are diagnosed with diabetes use. It allows them to track glucose levels as a way of managing lifestyle and treatment decisions.

The AIC test is not always accurate for certain ethnic groups. If you’re of African, Mediterranean, or Southeast Asian descent, results may skew higher or lower. Your doctor may need to order a different type of A1C test.

  • What the test results mean: As blood glucose levels rise, the percentage rises. A normal A1C level is below 5.7%. Prediabetes is between 5.7% and 6.4%. Diabetes is 6.5% or higher.

Random blood sugar test: Your doctor may choose this blood test if you are experiencing symptoms for diabetes. The test can be done immediately—no fasting required.

  • What the test results mean: If your blood sugar level is 200 mg/dc, you have diabetes.

Oral Glucose Tolerance Test (OGTT): The OGTT involves drinking a sweet/sugary drink and then checking blood glucose 2 hours after. If the blood glucose level is 200 mg/dl or higher, diabetes type 2 is diagnosed. This test is most commonly done in pregnant females.

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Urine tests for diabetes

Urine tests are typically for people who have already been diagnosed with diabetes and have very high blood sugar levels. It is not typically for diagnosing diabetes and can be less reliable than blood glucose tests.

The urine test checks for ketones, a byproduct of fat metabolism. Ketones are produced when the body burns fat for energy instead of glucose. This happens when there’s not enough insulin to move glucose from the blood into muscles, which it needs for energy. Ketones are much more common in type 1 diabetes than type 2.

How can I check if I have diabetes?

Home blood glucose meters are typically for people who have diabetes and want to monitor their glucose levels daily. They may also be helpful for people with prediabetes. The meters come with lancets but you'll have to purchase the test strips.

  • Fast overnight.
  • Place the test strip on the meter.
  • Prick finger with the lancet.
  • Squeeze the blood drop onto a test strip.
  • If you are positive, contact your doctor.

Dr. Rx

A home blood glucose meter may be an easy way to track blood sugar levels. They are available at the drugstore and online. —Dr. Rehman

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