Connect with others who understand.

sign up log in
About DiabetesTeam

Diabetes – The Path to Diagnosis

Updated on October 18, 2021
Medically reviewed by
Robert Hurd, M.D.
Article written by
Kelly Crumrin

Type 2 diabetes is easy to diagnose once someone gets tested for it. As many as one-third of people with type 2 diabetes do not know they have the disease. Early on, diabetes symptoms are mild and may be easily confused with other conditions or signs of aging.

Type 2 diabetes is most commonly diagnosed in people age 45 or older, but younger adults and even children can develop type 2 diabetes too. Routine testing is recommended for people who:

  • Are age 45 or older
  • Are between the ages of 19 and 44, and overweight or obese
  • Are between the ages of 10 and 18, overweight or obese, with additional risk factors such as family history of diabetes or low birth weight
  • Had gestational diabetes while pregnant
  • Are currently pregnant

Most people are diagnosed with diabetes by their primary care physician or family doctor. Your general practitioner may continue to treat your diabetes, or they may refer you to an endocrinologist. Endocrinologists specialize in diseases of the glands and hormone imbalance — diabetes involves problems with the pancreas, a gland that produces the hormone insulin. Read more about causes of diabetes.

How Is Type 2 Diabetes Diagnosed?

The doctor will draw a small blood sample to test your blood glucose level. In people with type 2 diabetes, cells become resistant to insulin. Insulin is the hormone necessary to allow cells to take in glucose from the bloodstream and regulate how much glucose remains in your blood. As diabetes progresses, cells can take in less and less glucose, and blood glucose levels rise.

There are several ways of testing blood glucose. The doctor will likely repeat the blood test on another day soon after to make sure the diagnosis is correct.

A1C

The results of the A1C test, also referred to as HbA1c, glycated hemoglobin, or glycohemoglobin test, show your average blood glucose over the past two to three months. A1C is used to diagnose type 2 diabetes and to monitor how well blood glucose is being managed in people taking treatments for type 2 diabetes.

A1C is expressed as a percentage.

  • Less than 5.7 percent is considered normal.
  • 5.7 percent to 6.4 percent indicates prediabetes.
  • 6.5 percent or higher indicates diabetes.

Oral Glucose Tolerance Test (OGTT)

For the OGTT, the doctor will take a blood sample, then provide a sweet beverage with a high glucose content. After waiting two hours, another blood sample will be taken to check how your blood glucose level has risen in response to the drink.

OGTT results are expressed in milligrams of glucose per deciliter of blood (often written as mg/dL).

  • Less than 100 milligrams per deciliter after an eight-hour fast is considered normal.
  • 100 to 125 milligrams per deciliter indicates prediabetes.
  • 126 milligrams per deciliter or higher indicates diabetes.

Fasting Plasma Glucose (FPG)

A fasting plasma glucose test is usually scheduled early in the morning. For an accurate result, you should fast — not eat or drink anything but water — for at least eight hours before the blood sample is taken.

Results are expressed in milligrams of glucose per deciliter, and diagnostic ranges are the same as for the oral tolerance test.

Random Plasma Glucose Test

A blood sample for a random or casual blood glucose test can be taken at any time. Results are expressed in miligrams per deciliter. A test result of 200 milligrams per deciliter or higher indicates diabetes. Any test would need to be repeated to confirm the diagnosis of type 2 diabetes.

Condition Guide

References

  1. Diabetes — Mayo Clinic
  2. Diagnosing Diabetes and Learning About Prediabetes — American Diabetes Association
  3. Diabetes Tests & Diagnosis — National Institute of Diabetes and Digestive and Kidney Diseases Health Information Center

All updates must be accompanied by text or a picture.
Robert Hurd, M.D. is a professor of endocrinology and health care ethics at Xavier University. Review provided by VeriMed Healthcare Network. Learn more about him here.
Kelly Crumrin is a senior editor at MyHealthTeam and leads the creation of content that educates and empowers people with chronic illnesses. Learn more about her here.

Related articles

Many members of DiabetesTeam have wondered about how magnesium levels relate to diabetes. One...

Magnesium for Diabetes: Does It Help?

Many members of DiabetesTeam have wondered about how magnesium levels relate to diabetes. One...
There are several types of diabetes. Most forms of diabetes are chronic — lasting throughout...

Types of Diabetes

There are several types of diabetes. Most forms of diabetes are chronic — lasting throughout...
Type 2 diabetes develops when the body becomes resistant to insulin, the hormone that allows...

What Causes Type 2 Diabetes?

Type 2 diabetes develops when the body becomes resistant to insulin, the hormone that allows...
Type 2 diabetes is a chronic disease in which your body is unable to regulate the levels of...

Type 2 Diabetes – An Overview

Type 2 diabetes is a chronic disease in which your body is unable to regulate the levels of...
We all respond differently to information about our health. After learning you have type 2...

You’ve Just Been Diagnosed With Diabetes. Now What?

We all respond differently to information about our health. After learning you have type 2...

Recent articles

After being diagnosed with diabetes when I was 21 years old, I was immediately thrown into a...

Member Perspective: How I Manage My A1c Levels

After being diagnosed with diabetes when I was 21 years old, I was immediately thrown into a...
Living with diabetes can be expensive, including the costs of insulin and other medications and...

How To Find Financial Support for Diabetes Treatment

Living with diabetes can be expensive, including the costs of insulin and other medications and...
Living with type 2 diabetes can often mean trying a series of dietary and lifestyle changes...

Life After 65 With Diabetes

Living with type 2 diabetes can often mean trying a series of dietary and lifestyle changes...
If you have diabetes, it’s important to work with your health care team to advocate for yourself...

Staying in Control of Your Diabetes

If you have diabetes, it’s important to work with your health care team to advocate for yourself...
The connection between rheumatoid arthritis (RA) and diabetes mellitus — commonly referred to as...

Diabetes and Rheumatoid Arthritis: Understanding the Connection

The connection between rheumatoid arthritis (RA) and diabetes mellitus — commonly referred to as...
One of the biggest concerns about diabetes is that it places people at higher risk for other...

Psoriatic Arthritis and Diabetes: What’s the Connection?

One of the biggest concerns about diabetes is that it places people at higher risk for other...
DiabetesTeam My diabetes Team

Thank you for subscribing!

Become a member to get even more:

sign up for free

close