Diabetes Test Results: Types of Tests and How to Read Them

Diabetes is a chronic condition that can cause serious health issues like stroke and heart disease. According to the Centers for Disease Control and Prevention (CDC), 37 million people in the United States are currently diagnosed with diabetes, and another 8.5 million people have yet to be diagnosed.

Testing for diabetes can screen for the condition and lead to an early diagnosis.

This article will discuss the different types of diabetes tests like A1C and fasting blood sugar. It will also cover diabetes symptoms and risk factors.

Healthcare provider holding vials of blood.

Yoshiyoshi Hirokawa / Getty Images

Who Should Get Tested?

The US Preventative Services Task Force (USPSTF) recommends screening for prediabetes and type 2 diabetes for:

  • People 35 to 70 years of age who are overweight or people with obesity
  • Anyone who has symptoms or several risk factors for diabetes should also be tested.
  • People who are pregnant should be tested for gestational diabetes between 24 and 28 weeks of their pregnancy. If someone is at high risk for gestational diabetes, their healthcare provider may recommend they get tested earlier.

Risk Factors

Several risk factors are linked to type 2 diabetes. They include:

  • Prediabetes
  • Overweight
  • 45 years old or older
  • Sedentary lifestyle
  • Family history of diabetes
  • Previous history of gestational diabetes
  • African American, American Indian, Alaska Native, Hispanic or Latino person

The risk factors for type 2 diabetes are either related to lifestyle or genetics. While someone cannot change their genetic predisposition to a condition, they can make lifestyle changes that can reduce the likelihood of a diabetes diagnosis.


The symptoms of diabetes can be non-specific and hard to identify. They develop gradually over time, so someone may not notice the symptoms. Type 2 diabetes generally starts in adulthood but has been seen in more young adults and children in recent years.

Here are the symptoms of diabetes:

  • Very thirsty
  • Frequent urination
  • Dry skin
  • Tiredness
  • Frequent hunger
  • Slow healing wounds
  • Frequent infections

Anyone with diabetes symptoms should contact their healthcare provider for a diabetes test.

Diabetes Test Result Chart
A1C Fasting Blood Sugar Glucose Tolerance Test
Normal Less than 5.7%  Less than 99 mg/dL Less than 140 mg/dL
Prediabetes 5.7%-6.4% 100-125 mg/dL 140-199 mg/dL
Diabetes 6.5% or greater 126 mg/dL or greater  200 mg/dL or greater

A1C Test

Unlike most diabetes tests which give a quick snapshot of a person's blood sugar, the A1C is a blood test that measures your blood sugar over a long period. An A1C is the average blood sugar level over two or three months.

A1C results inform a healthcare provider if someone is normal, prediabetic, or has diabetes. The results are as follows:

  • Normal: Less than 5.7%
  • Prediabetes: 5.7% to 6.4%
  • Diabetes: 6.5% or higher

Fasting Blood Sugar Test

A fasting blood sugar test screens for diabetes. To prepare for the test, one must fast (no eating) the night before the blood test, or for eight to 12 hours. Drinking water is permitted. Fasting blood sugar test results are as follows:

  • Normal: 99 milligrams per deciliter or less
  • Prediabetes: 100 to 125 milligrams per deciliter
  • Diabetes: 126 milligrams per deciliter or higher

A fasting blood sugar test looks at a person's blood sugar levels to evaluate how well their body uses insulin. When someone eats, their blood sugar levels rise, and their body releases insulin. The insulin stores the sugar for energy later on. People who are diabetic or prediabetic do not make enough insulin or cannot use insulin properly. As a result, their blood sugar levels will remain high after eating.

Glucose Screening Test

A glucose screening test is often used in pregnant people to test for gestational diabetes between 24 and 28 weeks of pregnancy.

A person will drink a sugary liquid given to them by their healthcare provider and then have their blood sugar measured one hour later.

  • Normal: 140 milligrams per deciliter or less

If the test comes back at greater than 140 milligrams per deciliter, the person will need a glucose tolerance test for further evaluation.

Glucose Tolerance Test

A glucose tolerance test is given if someone has a glucose level higher than 140 milligrams per deciliter.

During a glucose tolerance test, a person will fast overnight and have their glucose tested the next day to find their fasting blood sugar level. After that, they will drink a sugary drink given to them by a healthcare provider and have their blood sugars checked after one hour, two hours, and in some cases, three hours later.

The results of a glucose tolerance test two hours after the drink are as follows:

  • Normal: 140 milligrams per deciliter or less
  • Prediabetes: 140 to 199 milligrams per deciliter
  • Diabetes: 200 milligrams per deciliter or higher

Random Blood Sugar Test

A random blood sugar test is exactly what it sounds like. A blood sugar test that is done at any time, without regard to what the person has eaten or drank.

A result of 200 milligrams per deciliter or higher indicates that the person has diabetes. A healthcare provider may do additional testing to confirm the result.


Several types of blood sugar tests are available to determine if someone has diabetes. Many tests require the person to fast (no eating) for a period before the test. Whereas others do not have any fasting requirements. A healthcare provider will interpret the results and determine if additional testing is necessary.

A Word From Verywell

Diabetes is a common chronic condition that can go unnoticed. Regular diabetes screening with blood tests can help get an early diagnosis and allow your healthcare provider to form a treatment plan. Properly treating your diabetes can lessen the risk of developing other conditions caused by diabetes, like heart or kidney disease.

Frequently Asked Questions

  • What is the normal range for blood sugar?

    The normal range for blood sugar will depend on when the last time a person has eaten. A normal fasting blood sugar is less than 99 milligrams per deciliter. After meals, normal blood sugar is less than 140 milligrams per deciliter.

  • Can a blood test show that you have diabetes?

    Yes, a blood test that measure a person's blood glucose levels can show if someone has diabetes. A healthcare provider can interpret the results and guide a person through the right treatment plan.

  • Does normal blood sugar change as you age?

    Yes, normal blood sugar levels change as someone ages. When people get older, blood sugars are not as tightly controlled because they are at higher risk for developing low blood sugars (hypoglycemia).

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Force UPST, Davidson KW, Barry MJ, et al. Screening for prediabetes and type 2 diabetes: US preventive services task force recommendation statementJAMA. 2021;326(8):736-743. doi:10.1001/jama.2021.12531

  2. National Institute of Diabetes and Digestive and Kidney Diseases. Diabetes tests & diagnosis.

  3. Centers for Disease Control and Prevention. Diabetes tests.

  4. Centers of Disease Control and Prevention. Diabetes risk factors.

  5. Centers for Disease Control and Prevention. Diabetes symptoms.

  6. Centers for Disease Control and Prevention. What is diabetes?

By Patty Weasler, RN, BSN
Patty is a registered nurse with over a decade of experience in pediatric critical care. Her passion is writing health and wellness content that anyone can understand and use.