The short version
- Type 2 diabetes usually causes no symptoms for years. A simple blood test is the only reliable way to catch it early.
- Diabetes Canada recommends screening every three years for everyone 40 and older, and earlier or more often for people with risk factors.
- Family history, a history of gestational diabetes, high blood pressure, carrying extra weight around the middle, and being of Arab, South Asian, African, Asian, Hispanic or Indigenous descent all raise your risk.
- The two usual tests are the A1C, which needs no fasting, and the fasting blood sugar, which needs eight hours without food.
- Prediabetes is common and is a warning, not a diagnosis. Lifestyle changes can substantially lower the chance it becomes diabetes.
- Our doctors can assess your risk, order your bloodwork and go through the results with you, in English or Arabic.
November is Diabetes Awareness Month in Canada, and World Diabetes Day falls on November 14. It is a good moment to ask a question many adults have never asked their doctor: when was my blood sugar last checked?
Diabetes Canada estimates that millions of Canadians are living with diabetes or prediabetes, and a large share of type 2 diabetes goes undiagnosed for years because it does not feel like anything at first. By the time symptoms show up, the high blood sugar may already have started to affect the eyes, kidneys, nerves, heart and blood vessels. Screening exists to close that gap. This guide explains who should be tested, what the tests involve, what the numbers mean, and what to do next.
Why type 2 diabetes is easy to miss
In type 2 diabetes, the body either does not make enough insulin or does not use it properly, so sugar builds up in the blood. It develops slowly. Many people feel completely well, or put mild tiredness down to work, children or age.
When symptoms do appear, they can include unusual thirst, peeing more often, unexplained weight loss, blurred vision, cuts and sores that heal slowly, frequent infections, and tingling or numbness in the hands or feet. If you notice any of these, do not wait for a routine screening visit. Book an appointment or walk in, and mention them.
Who should be screened, and how often
Diabetes Canada's clinical practice guidelines, which Canadian family doctors follow, recommend:
- Everyone 40 and older: a screening blood test every three years.
- Anyone at high risk, at any age: screening now, and repeated every three years.
- People at very high risk or with several risk factors: testing every six to twelve months.
The guidelines also suggest that adults have their diabetes risk reviewed every year as part of routine care. Risk factors include:
- A parent, brother or sister with type 2 diabetes.
- Being of African, Arab, Asian, Hispanic, Indigenous or South Asian descent. Diabetes develops at higher rates, and often at younger ages and lower body weights, in these communities.
- A past result in the prediabetes range.
- Diabetes during a pregnancy (gestational diabetes), or having given birth to a baby weighing more than 4 kilograms.
- High blood pressure, high cholesterol or triglycerides, heart disease or stroke.
- Carrying extra weight, especially around the waist.
- Smoking.
- Conditions such as polycystic ovary syndrome, fatty liver disease, sleep apnea, gout, or past pancreatitis.
- Long term use of some medicines, including steroids and certain antipsychotics.
If you want a sense of your own risk before your visit, the Public Health Agency of Canada's free CANRISK questionnaire takes about five minutes online. Bring your score, but do not let a low score talk you out of testing if you are 40 or older or have a strong family history.
The tests, and how to prepare
Screening uses one or both of two blood tests, done at a community lab with a requisition from your doctor.
- A1C (hemoglobin A1C). Shows your average blood sugar over the past two to three months. No fasting is needed, so you can go to the lab at any time of day.
- Fasting plasma glucose. Measures your blood sugar at that moment, after at least eight hours with nothing to eat or drink except water. Most people book an early morning lab appointment and eat afterwards.
If your results are borderline, your doctor may also order a glucose tolerance test, which measures your blood sugar two hours after a sweet drink. Take your usual medicines on the day of any test unless your doctor tells you otherwise.
What your numbers mean
These are the ranges Canadian doctors use. A single high result is usually repeated on another day before a diagnosis of diabetes is made, unless you also have clear symptoms.
Scroll sideways to see the full table.
| Result | A1C | Fasting glucose |
|---|---|---|
| Normal range | Below 6.0% | Below 6.1 mmol/L |
| Prediabetes | 6.0% to 6.4% | 6.1 to 6.9 mmol/L |
| Diabetes | 6.5% or higher | 7.0 mmol/L or higher |
A1C can read falsely high or low in some situations, including certain inherited blood conditions that are more common in people of Mediterranean, Middle Eastern, African and Asian descent, and some kinds of anemia. If that applies to you, your doctor may rely on the fasting test instead.
If you have prediabetes
Prediabetes means your blood sugar is higher than normal but not high enough to be called diabetes. It is very common, and it is the best possible time to act, because the trend can often be slowed or reversed.
Large studies have shown that modest, sustained changes can roughly halve the chance of prediabetes progressing to type 2 diabetes. In practice, that usually means:
- Losing 5 to 10 percent of your body weight if you are carrying extra weight. For a 90 kilogram adult, that is 4.5 to 9 kilograms.
- Building up to about 150 minutes a week of moderate activity, such as brisk walking, plus some strength exercise.
- Cutting back on sugary drinks, white bread and rice, and large portions, and filling more of the plate with vegetables, legumes and whole grains.
- Stopping smoking, and getting enough sleep.
Your doctor will usually recheck your blood sugar every six to twelve months, and may also check your blood pressure, cholesterol and kidney function, since these risks tend to travel together.
If you are diagnosed with diabetes
A diagnosis is the start of a plan, not a verdict. Many people with type 2 diabetes keep it well controlled for decades with a combination of lifestyle changes and medicine. Good care includes regular A1C checks, blood pressure and cholesterol management, yearly eye exams, kidney tests, and foot checks. Durham Region also has free diabetes education programs, run by nurses and dietitians, that we can refer you to.
Our physicians provide ongoing chronic disease care for diabetes, and Oshawa People Pharmacy, inside the clinic, can review your medicines and show you how to use a glucose meter. If you fast during Ramadan or for other reasons, please talk to your doctor well ahead of time so your medicines can be adjusted safely.
Getting screened at Simcoe Medical Clinic
Book an appointment, choosing a male or female doctor, or walk in during clinic hours. Your doctor will review your risk factors, check your blood pressure and give you a lab requisition. Once your results are back, we will go through them with you and agree on next steps. If you are already coming in for a flu shot or a checkup this fall, ask for your diabetes screening at the same visit.
We are accepting new patients of all ages, Arabic is spoken at the clinic, and there is free parking on site at 115 Simcoe St. South. We are open Monday to Friday from 9:00 AM to 6:00 PM and Saturday from 10:00 AM to 4:00 PM.
Common questions
It depends on the test. The A1C test does not need any fasting. The fasting plasma glucose test needs at least eight hours with nothing to eat or drink except water, so most people book an early morning lab visit. Your requisition will say which tests your doctor has ordered.
If you have risk factors, yes. Diabetes Canada recommends screening at any age for people at high risk, such as those with a parent or sibling with type 2 diabetes, a history of gestational diabetes, high blood pressure, or Arab, South Asian, African, Asian, Hispanic or Indigenous descent. Ask your doctor at your next visit.
Every three years if you are 40 or older or at high risk, and every six to twelve months if you are at very high risk or have prediabetes. Your doctor will set the right interval for you.
Often, yes. Losing 5 to 10 percent of your body weight if you are carrying extra weight, staying active, and improving your diet can bring blood sugar back into the normal range for many people, and substantially lower the chance of developing type 2 diabetes.
Yes. Our doctors can review your risk factors and give you a lab requisition at a walk-in or booked visit. We then go through your results with you once they are back.
Yes. A history of gestational diabetes significantly increases the chance of developing type 2 diabetes later in life. Regular screening is recommended, and it is worth telling any new doctor about it.
This article is general information for Ontario residents and does not replace medical advice. Screening recommendations are based on Diabetes Canada clinical practice guidelines and may change. Your doctor will interpret your results alongside your own history. For medical emergencies, call 911 or visit the nearest emergency department.