Type 2 diabetes often develops quietly, without obvious symptoms, which is exactly why screening matters. A simple blood test can catch high blood sugar years before it causes harm, giving you a real chance to act early. This article focuses on the screening decision itself, who should get tested, how often, and what the A1C test tells you, plus how to arrange it here in Ottawa.
Who should be screened, and how often
Diabetes Canada recommends that adults aged 40 and older be screened for diabetes about every three years using either a fasting blood glucose test or an A1C. If you have added risk factors, screening is recommended earlier and more often, sometimes yearly, because your chances of developing the condition are higher.
- A close family member with type 2 diabetes
- Being overweight, especially with weight carried around the abdomen
- High blood pressure or high cholesterol
- A history of gestational diabetes or prediabetes
- Belonging to a higher-risk population, including South Asian, Indigenous, African, Hispanic, or Asian communities
- A relatively inactive lifestyle
Your own doctor or nurse practitioner will decide the right starting age and interval for you. The point of screening is to test before symptoms appear, so do not wait for thirst, fatigue, or frequent urination to prompt a check.
What the A1C test measures
The A1C test reflects your average blood sugar over roughly the past three months. It works by measuring the share of your hemoglobin, the oxygen-carrying protein in red blood cells, that has glucose attached to it. Because red blood cells live for about three months, A1C gives a longer-term picture than a single glucose reading, which only captures one moment in time.
A1C versus fasting glucose
Both tests are accepted for screening, but they work differently, and the practical difference for you often comes down to fasting.
- A1C: a three-month average; no fasting is required, so you can be tested at any time of day
- Fasting glucose: a snapshot of your blood sugar after not eating; it does require fasting, typically 8 to 12 hours, with water fine but no coffee, tea, food, or gum
Because A1C needs no fasting, many people find it the more convenient option, which is one reason it is popular for routine screening. Your requisition will indicate which test your provider has ordered and whether fasting is required.
Understanding prediabetes
Screening does not just find diabetes; it also flags prediabetes, where blood sugar is higher than normal but not yet in the diabetic range. Prediabetes is an important early warning, because it often responds well to changes in diet and activity and does not have to progress. Catching it is one of the biggest reasons regular screening is worthwhile.
A quick note on scope
This article is about deciding when to screen. If you want more detail on the A1C test itself and local logistics, see our guide to the A1C test in Ottawa. For a broader look at living with the condition, including types, management, and diet, read our article on diabetes. Together they complement the screening decision covered here.
Getting screened at Bio-Test in Ottawa
Once your physician or nurse practitioner has given you a requisition, Bio-Test makes screening easy. Most bloodwork is walk-in, no appointment needed, first-come, first-served, at any of our 11 locations across Ottawa-Carleton and Eastern Ontario. Bring your Ontario health card and requisition. An A1C needs no fasting, so you can come any time we are open; if a fasting glucose is ordered too, mornings are best. You can also book online through our patient portal, and home visits are available by request for a fee.