PATIENT INFORMATION LEAFLET
Diabetes screening and the A1C test
A simple blood test can find high blood glucose before type 2 diabetes causes noticeable symptoms.
Reviewed by the Verra Health clinical team · Last reviewed September 2026
What is diabetes screening?
Screening checks for type 2 diabetes or prediabetes in people who do not have clear symptoms. It is different from testing someone who already has symptoms or a known diagnosis. Early identification gives you time to discuss lifestyle support, monitoring, and treatment if needed.
Who should be screened?
- Adults aged 40 and older should generally be screened every 3 years.
- People at higher risk may need screening at a younger age or more often.
- Risk factors include a parent, brother, or sister with diabetes; a history of gestational diabetes; high blood pressure; abnormal cholesterol; higher body weight; physical inactivity; or belonging to a population at higher risk of type 2 diabetes.
Your clinician may use a risk calculator and your health history to decide when testing is useful. A screening schedule is individualized.
What tests are used?
| Test | What it measures | Fasting? |
|---|---|---|
| A1C | Average blood glucose over about 2–3 months | Usually no |
| Fasting blood glucose | Blood glucose after not eating for a specified period | Yes |
| Oral glucose tolerance test | How your body handles a measured glucose drink | Preparation required |
A1C is often convenient, but it is not suitable or fully reliable in every situation. Pregnancy, anemia, recent blood loss or transfusion, kidney disease, and some hemoglobin conditions can affect the result. Tell your clinician about relevant health conditions.
What do the results mean?
Normal: Your result is below the range used for prediabetes. Continue screening when it is due, especially if your risk changes.
Prediabetes: Your blood glucose is higher than usual but not in the diabetes range. This is a chance to discuss practical steps and follow-up; it does not mean you will definitely develop diabetes.
Diabetes range: The result may meet a diagnostic threshold, but your clinician must interpret it in context. If you do not have symptoms, testing is often repeated or confirmed with another test.
Frequently asked questions
Who should be screened for type 2 diabetes?
Diabetes Canada recommends screening every 3 years for adults aged 40 and older, and for people at higher risk at any age. Your clinician may recommend testing sooner or more often based on your risk.
What is an A1C test?
A1C is a blood test that estimates your average blood glucose over the previous 2 to 3 months. It usually does not require fasting, although your lab or clinician may give you other instructions.
What is the difference between diabetes and prediabetes?
Prediabetes means blood glucose is higher than usual but not in the diabetes range. It increases the chance of developing type 2 diabetes, but lifestyle support and follow-up can help reduce risk.
Can I have diabetes if I feel well?
Yes. Type 2 diabetes can develop gradually without obvious symptoms. Screening is useful because it can identify high blood glucose before complications or noticeable symptoms appear.
Discuss your screening plan
Ask your family doctor, nurse practitioner, or clinic when diabetes screening is appropriate for you. Bring your medication list, family history, and any previous blood test results if available.
Trusted information
- Diabetes Canada: screening and diagnosis
- Canadian Task Force: type 2 diabetes screening
- Verra Health: prediabetes resource
This leaflet is for general education and does not replace individualized medical advice.