Diabetes Tests

What are diabetes tests?

Diabetes, also known as diabetes mellitus, is a disease that affects how your body uses glucose (blood sugar). Glucose is your body's main source of energy. A hormone called insulin helps move glucose from your bloodstream into your cells. If you have diabetes, your body can't make insulin or insulin doesn't work like it should. This can cause glucose levels to get too high, which can lead to serious health problems. These include heart disease, nerve damage, eye problems, and kidney disease. Diabetes tests measure glucose levels in blood or urine to see if you are at risk for or have diabetes.

Other names: blood glucose, fasting plasma glucose, FPG, oral glucose tolerance test, OGTT, glucose screening test, glucose in urine test, hemoglobin A1c, random blood sugar

What are they used for?

Diabetes tests are used to screen for and/or diagnose the following:

• Type 1 diabetes. If you have type 1 diabetes, your body makes little or no insulin at all. This condition happens when your immune system attacks and destroys cells that produce insulin. It can develop at any age, but it most often starts in childhood. People with type 1 diabetes must take daily doses of insulin, either by injection or a special pump
• Type 2 diabetes. This is the most common form of diabetes. If you have type 2 diabetes, your body may still be able to make insulin, but the cells in your body don't respond well to insulin and can't easily take up enough glucose from your blood. Type 2 diabetes may be caused by your genes and lifestyle factors, such as being overweight or having obesity. The condition most often occurs in adulthood but is becoming more common in children and teens.
• Gestational diabetes. This is a form of diabetes that happens only during pregnancy.
• Prediabetes. This is a condition in which your blood glucose levels are higher than normal, but not high enough to be considered diabetes. But it may put you at risk for getting diabetes.

Why do I need a diabetes test?

You may need testing if you have symptoms of diabetes, such as:

• Increased thirst
• Frequent urination
• Increased hunger
• Fatigue
• Blurred vision
• Unexplained weight loss
• Sores that are slow to heal
• Numbness or tingling in the feet

Symptoms of type 1 diabetes usually come on quickly and can be severe. Symptoms of type 2 diabetes and prediabetes often develop slowly, even over the course of years.

Gestational diabetes doesn't usually cause symptoms in the early stages of pregnancy, but most pregnant women are screened for the condition. If testing shows glucose levels are high, you will be tested again to confirm the diagnosis.

You may also need testing if you have certain risk factors. You may be at higher risk for diabetes if you:

• Are over 45 years old. The American Diabetes Association recommends annual diabetes screening for all adults aged 45 years and older.
• Have prediabetes
• Are overweight or obese
• Have a family history of diabetes
• Have high blood pressure or heart disease
• Previously had gestational diabetes

What happens during a diabetes test?

There are several ways to screen for and diagnose diabetes. Most tests involve measuring glucose levels in the blood.

To get a blood sample, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

The different types of glucose blood tests include:

• Blood glucose test, also known as fasting blood glucose. Before the test, you will need to fast (not eat or drink) for eight hours before the test. This test is often used as a screening test for diabetes. It may be repeated to confirm a diagnosis.
• Oral glucose tolerance test (OGTT). This test also requires fasting before the test. When you arrive for your test, a blood sample will be taken. You will then drink a sugary liquid that contains glucose. About two hours later, another blood sample will be taken.
• Random blood sugar. This test can be taken at any time. No fasting is required.
• Hemoglobin A1c (HbA1c). This test measures the average amount of glucose attached to hemoglobin over the past 3 months. Hemoglobin is the part of your red blood cells that carries oxygen from your lungs to the rest of your body. No fasting is required for this test.

Glucose may also be measured in urine. Urine tests are not used to diagnose diabetes but may show if you are at risk for getting the disease. If your glucose in urine levels are higher than normal, you will probably need a blood test to confirm the diagnosis.

For a glucose in urine test, your provider may recommend an at-home test kit. The kit will include a test strip that you hold under your stream of urine. The test strip will change colors to show different levels of glucose.

Will I need to do anything to prepare for this test?

You will need to fast (not eat or drink) for a blood glucose and an oral glucose tolerance test.

You don't need any special preparations for a random blood sugar, hemoglobin A1c, or glucose in urine test.

Are there any risks to this test?

There is very little risk to having a blood test. There may be slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

There is no risk to having a urine test.

What do the results mean?

Depending on the type of test or tests you had, your results may show one of the following:

• Normal glucose levels. This means you probably are not at risk for or do not have diabetes.
• Prediabetes. This means you have higher than normal glucose levels and may be at risk for getting diabetes.
• Type 1 or type 2 diabetes
• Gestational diabetes

If you have been diagnosed with type 1 diabetes, talk to your provider about how to best manage the condition. There is no cure for type 1 diabetes, but it may be controlled with regular glucose monitoring and taking insulin.

If you've been diagnosed with prediabetes or type 2 diabetes, your condition may be managed or even reversed by taking diabetes medicines and making lifestyle changes. These include eating a healthy diet, losing weight, and increasing exercise.

If you've been diagnosed with gestational diabetes, you may be able to lower your glucose levels by eating a healthy diet and getting regular exercise. But be sure to talk to your provider about treatment options. Most of the time, gestational diabetes goes away after giving birth.

If you have other questions about your diabetes diagnosis or treatment, talk to your health care provider.

Learn more about laboratory tests, references ranges, understanding results.

Is there anything else I need to know about diabetes testing?

If you've been diagnosed with type 1 diabetes, you will need to monitor blood glucose levels daily, often several times a day. Your health care provider can recommend a kit you can use at home. Most kits include a lancet, a device that pricks your finger. You will use this to collect a drop of blood for testing. There are some newer kits available that don't require pricking your finger. Some pregnant women with gestational diabetes may also need to monitor their glucose levels in this way.

People with type 2 diabetes will also have to check their blood sugar on a regular basis. If you have type 2 diabetes, talk to your provider about how often it should be checked.

People with type 2 diabetes may also need to have their insulin levels checked regularly. Insulin plays a key role in keeping glucose at the right levels. An insulin in blood test is done at a provider's office.