To make a type 2 diabetes diagnosis, doctors can use several different blood tests. You’ll typically need to be tested at least twice to confirm a diagnosis. Most people are tested for diabetes because of age or other risk factors.

Diabetes is a long-term (chronic) condition that happens when your body doesn’t produce enough insulin, or can’t use insulin well. As a result, your blood sugar can become too high, which can lead to serious health problems over time.

The good news is that type 2 diabetesisa manageable condition. Once you’re diagnosed, you can work with your doctor to develop a treatment plan to stay healthy. Early diagnosis and management is important to help prevent serious outcomes.

Read on to learn more about the early signs of type 2 diabetes, the tests doctors use to diagnose the condition, and what to expect during the testing process.

Types of diabetes

The three main types of diabetes are gestational diabetes, type 1 diabetes, and type 2 diabetes.

Gestational diabetes

Gestational diabetes happens when you develop high blood sugar during pregnancy. It’s important to manage gestational diabetes well to reduce the risk of complications for you or your baby.

Gestational diabetes usually goes away after the baby is born. But having gestational diabetes increases your risk for developing type 2 diabetes. After pregnancy, your doctor will test your blood sugar level to make sure you no longer have diabetes.

Type 1 diabetes

People with type 1 diabetes don’t produce insulin in their bodies. As a result, they need to take insulin every day. Type 1 makes up 5 to 10 percent of all cases of diabetes, according to the Centers for Disease Control and Prevention (CDC). It’s usually diagnosed by early adulthood.

Type 2 diabetes

Type 2 diabetes has a different cause than type 1 diabetes. Unlike those with type 1, people with type 2 diabetes can produce insulin, but their bodies don’t use it very well.

This type makes up 90 to 95 percent of all diagnosed cases of diabetes. It’s sometimes called adult-onset diabetes. Although it can occur at any age, type 2 diabetes is more common in people older than 45.

If you think you might have diabetes, talk to your doctor. Uncontrolled type 2 diabetes can cause severe complications, such as:

Type 2 diabetes is also associated with high cholesterol. It can cause your LDL or “bad” cholesterol and triglycerides to go up, and your HDL or “good” cholesterol to go down. These changes can increase your risk of cardiovascular disease.

While diabetes can usually be managed well, it’s important to take your treatment plan seriously. According to the CDC, diabetes is the 7th leading cause of death in the United States.

Many of the severe complications of diabetes can be avoided with treatment. That’s why an early diagnosis is so important.

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Some people are diagnosed with type 2 diabetes because they have noticeable diabetes symptoms. Early symptoms can include:

  • increased or frequent urination
  • increased thirst
  • fatigue
  • blurry vision

Skin conditions

There are also several skin conditions that can sometimes be a sign of diabetes. These include:

  • cuts and sores that won’t heal. The effects of high blood sugar can reduce your skin’s ability to heal. This can lead to infections and skin ulcers.
  • darker, thicker, velvety skin in places where your skin folds. Acanthosis nigricans is a skin pigment condition found in areas like your armpits, neck, hands, knees, groin, and inside the elbows.
  • skin tags. These tiny growths of skin usually happen on your eyelids, armpits, neck, and groin.
  • raised bumps that turn into patches of solid, hard skin. Necorbiosis lipoidica can cause yellow, brown, or reddish patches to form on your skin.
  • unusually thick, hard skin on your fingers, toes, or both. Digital sclerosis can make it difficult to move your fingers.
  • a rash of small, itchy, painful, pimple-like bumps that turn yellow. Eruptive xanthomatosis can happen when a person has high triglycerides. Often, people diagnosed with eruptive xanthomatosis have diabetes. But this condition also happens in people who do not have diabetes.
  • shin spots. Diabetic dermopathy causes visible spots or lines that create a small dent in the skin.

Keep in mind that these symptoms, on their own, do not always indicate diabetes. But if you notice these changes, it’s a good idea to get them checked out by a doctor.

The symptoms of type 2 diabetes often develop gradually. Because you may or may not have symptoms, your doctor will use blood tests to confirm your diagnosis.

These blood tests can be used to measure the amount of sugar (glucose) in your blood:

  • A1C (glycated hemoglobin) test
  • fasting plasma glucose test
  • random plasma glucose test
  • oral glucose tolerance test

We’ll look at each of these tests in more detail later in the article.

Your doctor will request one or more blood tests to confirm your diagnosis. A test will usually be completed more than once to confirm the result, unless you have clear symptoms of diabetes.

What to expect during blood sugar testing

To do a blood test, a lab technician, nurse, or other healthcare professional will use a small needle to draw a sample of your blood. The sample is then sent to a lab for testing.

Some diabetes tests require you to prepare for the test. For example, you may be asked to fast (avoid eating and drinking) for a set period of time before the test. Your doctor will give you instructions to tell you how to prepare for your tests.

Your blood sugar test results can be affected by other health conditions or medications, so tell your doctor about any illness or stress you’re experiencing. And make sure your doctor knows about medications you’re taking.

Who should be tested for type 2 diabetes?

Most often, people are diagnosed with type 2 diabetes through routine screening tests. Routine screening means that you are tested because you may be at risk of having diabetes, even when you don’t have any signs or symptoms.

Routine screening for diabetes typically starts at age 45. You should be screened sooner if you have:

  • high blood pressure
  • cardiovascular disease
  • obesity or are overweight
  • polycystic ovary syndrome
  • acanthosis negricans, a skin condition
  • a family history of type 2 diabetes
  • a history of gestational diabetes or you’ve given birth to a baby weighing over 9 pounds (4.1 killograms)
  • Black, Latino/Hispanic, Asian, Native American, Alaska Native, or Pacific Islander descent
  • a low level of HDL (“good”) cholesterol or a high triglyceride level
  • a sedentary lifestyle

Routine screening uses blood tests to check for signs of diabetes.

Next, let’s take a closer look at some blood tests commonly used to diagnose diabetes.

What is A1C?

The A1C test measures your average blood sugar level over the past 2 to 3 months. It’s sometimes called the glycated hemoglobin test.

This test measures the amount of glucose (sugar) attached to the hemoglobin in your blood. Hemoglobin is the oxygen-carrying protein in your red blood cells. The higher your A1C, the higher your recent blood sugar levels have been.

An advantage of the A1C test is convenience. You don’t have to fast before this test. And the blood sample can be collected at any time of day.

Here’s what your A1C test results could mean:

Below 5.7%Normal
5.7 to 6.4%Prediabetes
6.5% or higherDiabetes

A1C testing is also used to monitor your blood sugar control after you’ve been diagnosed with diabetes. If you have diabetes, your A1C levels should be checked at least twice a year.

Factors that can affect A1C results

A1C measures sugar that’s attached to hemoglobin in your blood. One type of hemoglobin, hemoglobin A, is the most common. But there are many more types of hemoglobin, known as hemoglobin variants. In some cases, having a hemoglobin variant can affect your A1C results.

About 7 percent of people around the world are born with hemoglobin variants, and most people don’t know they have it. Some hemoglobin variants are more common in people of African, Mediterranean, or Asian heritage.

Having a hemoglobin variant can cause your A1C test result to be incorrectly high or low. If your doctor finds that your A1C results don’t seem to be consistent with your symptoms or your other test results, they will likely ask for additional tests.

Some health conditions such as anemia, kidney disease, and liver failure can also affect A1C results. Don’t worry — your doctor will repeat the tests before making a diagnosis.

The fasting plasma glucose test measures your blood sugar at the time of the test. This is different from the A1C test, which measures blood sugar levels over a longer period of time.

For the fasting plasma glucose test, a sample of your blood will be taken after you’ve fasted for at least 8 hours, usually overnight. This means that you have consumed no food or drinks during that time. Your doctor will tell you if you can sip water while fasting before the test.

Your test results will usually be expressed in milligrams per deciliter (mg/dL).

Here’s what your results could mean:

Fasting plasma glucoseResult
up to 99 mg/dLNormal
100 to 125 mg/dLPrediabetes
126 mg/dL or higherDiabetes

Random blood sugar testing is usually used for people who have symptoms of diabetes. A random blood sugar test can be done at any time of day. You do not need to fast before this test.

No matter when you last ate, a random blood sugar test of 200 mg/dL or above suggests that you may have diabetes. This is particularly true if you already have symptoms of diabetes.

The oral glucose tolerance test (OGTT) measures your blood sugar before and after you drink a sugary liquid that’s specially formulated for the test. Like the fasting plasma glucose test, you’ll be required to fast overnight beforehand.

When you arrive at your appointment, you’ll first undergo a fasting blood sugar test. Then you’ll drink the sugary liquid. After you’re done, your doctor will test your blood sugar levels periodically for several hours.

This test detects diabetes better than other tests, such as the fasting plasma glucose test. But it’s more costly and takes longer than other blood sugar tests.

For an oral glucose tolerance test, here’s what your results could mean:

Oral glucose toleranceResult
up to 140 mg/dLNormal
140 to 199 mg/dLPrediabetes
200 mg/dL or higherDiabetes

A different version of this test is used to diagnose gestational diabetes. The numbers your doctor will use to make a diagnosis are also different.

Initially, your test results may vary. For instance, a fasting plasma glucose test may show that you have diabetes but an A1C test may show that you don’t. The reverse can also be true.

How does this happen? It could mean that you’re in an early stage of diabetes, and your blood sugar levels may not be high enough to show on every test. Some blood sugar test results can also vary day to day based on a variety of factors, like stress or illness.

Remember that your doctor will typically need to repeat any test to confirm your diagnosis.

You should always feel free to ask more questions or get a second opinion if you have any concerns or doubts about your results.

Once you know you have type 2 diabetes, you can work with your doctor to create a treatment plan. This can include a plan for:

  • healthy weight loss
  • changes to your diet
  • medication
  • regular blood sugar testing

It’s important to follow through with your treatments and medical appointments. Talk with your doctor about your blood sugar goal, and how often you should test your blood sugar. Monitoring your blood sugar regularly and tracking your symptoms are essential steps for your long-term health.

There’s no existing cure for type 2 diabetes. But this condition is highly manageable with many effective treatment options.

If you’re over the age of 45, are experiencing symptoms of diabetes, or you have a condition that increases your diabetes risk, talk to your doctor about getting tested.

The first step is taking the tests and understanding your test results. It’s important to go over your results with your doctor. To confirm your diagnosis, you doctor will usually need to test you more than once.

If you’re diagnosed with diabetes, work with your doctor to start a treatment plan that’s right for you.

By following your treatment plan, you can help to avoid the complications of diabetes.