Who Should Be Tested for Diabetes, and How is Diabetes Diagnosed?

Written by Kristin Della Volpe
Reviewed by Amy Hess-Fischl MS, RD, LDN, BC-ADM, CDE

Diabetes is diagnosed using one of four simple blood tests in a doctor’s office or health clinic. The tests measure your blood-glucose level, which means the amount of sugar in your blood. Many people with diabetes do not have symptoms so it is important to get tested if you have risk factors for the disease.

Who Should Be Tested For Diabetes
The American Diabetes Association recommends blood tests for diabetes in any person with symptoms of the disease. In people without symptoms, testing should begin at age 45 and every three years thereafter or earlier in adults who are overweight or obese—meaning a body mass index (a measure of body fat) ≥25 kg/m2—and have any of the following other risk factors:

In children and adolescents, testing for type 2 diabetes should be considered for those who have diabetes symptoms or who are overweight and have two of the following risk factors:

Testing in children should begin at age 10 or when the child enters puberty and should be repeated every 3 years.

BMI and Racial/Ethnic Groups
Some studies suggest that testing should be considered in people with a lower body mass index (BMI) who are of certain racial/ethnic groups, such as people of South Asian, Chinese, and African American descent. Talk to your doctor to see if you should be tested for diabetes.  

Tests Used to Diagnose Diabetes
The Table shows the types of blood tests used to diagnose diabetes and how they are performed. Typically, diabetes is diagnosed if test results are positive when tested on two separate days.

Table. Tests Used to Diagnose Diabetes


American Diabetes Association. Diagnosing Diabetes and Learning About Prediabetes. http://www.diabetes.org/diabetes-basics/diagnosis/?loc=db-slabnav Accessed September 15, 2014.

American Diabetes Guidelines. Diagnosis and Classification of Diabetes Mellitus. http://care.diabetesjournals.org/content/37/Supplement_1/S81.full.pdf+html Accessed September 15, 2014.

Joslin Diabetes Center. How Is Diabetes Diagnosed? https://www.joslin.org/info/how_is_diabetes_diagnosed.html. Accessed September 15, 2014.

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