What Tests Are Done for Diabetes? Diabetes Screening

Medically Reviewed on 4/28/2022
What Tests Are Done for Diabetes
Diabetes can cause serious complications if left untreated, which is why timely diagnosis is important. Learn about tests for type II, type I, and gestational diabetes

Diabetes can cause serious complications if left untreated, which is why timely diagnosis is important. Tests done for diabetes vary depending on the type:

What tests are done for type II diabetes?

With type II diabetes, the body generates enough insulin but is unable to use it properly (insulin resistance). Tests for type II diabetes include the following:

Fasting plasma glucose (FPG) test

FPG test requires an 8-hour fast beforehand and involves taking a blood sample to measure your blood sugar levels. Results are as follows:

  • Normal: 99 mg/dL or lower
  • Prediabetes: 100 to 125 mg/dL
  • Diabetes: 126 mg/dL or higher

Random plasma glucose (RPG) test

Fasting is not required for an RPG test. RPG tests may be recommended if you have symptoms such as unintentional weight loss, partial vision loss, frequent urination, or dehydration. Results are as follows:

  • Normal: Lower than 140 mg/dL
  • Prediabetes: 140 to 199 mg/dL
  • Diabetes: 200 mg/dL or higher

Hemoglobin A1C test

This test determines average blood sugar values, or hemoglobin A1c levels, for the last three months. Results are as follows:

  • Normal: Lower than 5.7%
  • Prediabetes: 5.7% to 6.4%
  • Diabetes: 6.5% and higher

What tests are done for type I diabetes?

Diagnosis of type I diabetes involves the same tests as those for type II diabetes, with a few additional ones:

Urine test

When your body no longer produces insulin, ketone bodies are created as adipose tissue is consumed for energy. As a result, the amount of ketone bodies in a urine sample can be used to diagnose diabetes. 


C-peptide is produced by the pancreas. With type I diabetes, the production of C-peptide decreases along with the production of insulin. 

C-peptide concentrations in the blood typically vary between 0.5 and 2.0 ng/mL. When your body produces high or low levels of insulin, these numbers might swing too high or too low.

Insulin autoantibodies

This test aids in the detection of antibodies that target insulin produced in the body. With type I diabetes, the immune system targets and destroys insulin. There may be other autoantibodies as well such as islet cell antibodies and antibodies against GAD-65.

Aside from these tests, FPG, HbA1c, postprandial plasma glucose and RPG tests are used to identify type I diabetes.

What tests are done for gestational diabetes?

Gestational diabetes occurs when the body is unable to efficiently use insulin during pregnancy, often caused by hormonal changes. Gestational diabetes can affect a baby's development in the womb and can lead to respiratory difficulties, obesity. and other health concerns after delivery. Screening for gestational diabetes includes the following tests:

Initial glucose challenge

The initial glucose challenge requires you to drink a glucose solution. After an hour, your blood sugar is tested. 

If your blood sugar level is less than 140 mg/dL, you are in the normal range. A blood sugar level of 190 mg/dL or more indicates gestational diabetes.

Follow-up glucose tolerance testing

This test requires you to fast overnight, after which your fasting blood sugar level will be checked. After your sugar levels have been measured, you will be required to drink a solution with a higher percentage of sugar, and another blood sugar test is done. This is done each hour for 3 hours.

If any of the two readings is above the typical levels, you are at risk of gestational diabetes.


Diabetes: What Raises and Lowers Your Blood Sugar Level? See Slideshow

What other tests are done for diabetes?

Zinc transporter 8 autoantibody (ZnT8Ab) test

The ZnT8Ab test may be ordered to determine the type of diabetes you have and help your doctor recommend appropriate treatment.

At-home tests

Several home kits are available that may be used to perform an RPG test. At-home diabetes tests typically involve pricking your fingertip to extract blood, which is then transferred to a glucose meter strip, which is then placed into a glucometer. Findings appear within 20-30 seconds. 

Continuous glucose monitoring devices can also help you track your blood glucose levels. These devices involve implanting a glucose sensor under your skin and wearing a gadget that displays the results. When your blood sugar levels increase or get too low, the device will notify you.

Who should get tested for diabetes?

The American Diabetes Association recommends getting screened for diabetes every 3 years starting at age 45. If you are at a high risk of diabetes, your doctor may advise you to get tested sooner or more frequently. Risk factors include:

Because people with prediabetes often do not have symptoms, it is essential to be aware of these risk factors and discuss concerns with your doctor.

What are symptoms of diabetes?

Diabetes, especially type II diabetes, can cause a wide range of symptoms in its early stages. Examples include:

Early warning signs may not be apparent for many years after the disease has begun. If you are at high risk of diabetes, talk to your doctor to start treatment right away.

How can I reduce my risk of diabetes?

  • Lose weight: Obesity is a risk factor for type II diabetes. Therefore, losing weight can help you reduce your risk of developing the disease.
  • Exercise regularly: Regular physical activity helps lower cholesterol, blood pressure, and blood glucose, all of which contribute to diabetes. Try to get at least 30 minutes of exercise 5 days a week.
  • Eat healthy: Eat a diet rich in vegetables, lean protein, and whole grains. Avoid added fats and added sugars. To keep your blood sugar under control, try eating smaller meals throughout the day.

Health Solutions From Our Sponsors

Medically Reviewed on 4/28/2022
Image Source: iStock Image

Diabetes Tests: https://www.cdc.gov/diabetes/basics/getting-tested.html

Diabetes Tests & Diagnosis: https://www.niddk.nih.gov/health-information/diabetes/overview/tests-diagnosis

Diabetes: An Overview: https://my.clevelandclinic.org/health/diseases/7104-diabetes-mellitus-an-overview

Diagnosis: https://www.diabetes.org/diabetes/a1c/diagnosis

HOW TO TEST FOR DIABETES TYPE: https://beyondtype1.org/how-to-test-for-diabetes-type/