Screening for and Diagnosing Diabetes

Healthcare Provider Tool

Measure Fasting Plasma Glucose (FPG) and/or A1C and enter test results:

  mmol/L     %

According to the list below, how many risk factors does the patient have?

Measure 75g Oral Glucose Tolerance Test (OGTT) and enter test results:

  mmol/L     mmol/L
Calculate Screening / Diagnosis Result


Rescreen as recommended, every 3 years.


Review Clinical Practice Guidelines' Chapter 4: Screening for Type 1 and Type 2 Diabetes for more detailed information.

  • Age ≥40 years
  • First-degree relative with type 2 diabetes
  • Member of high-risk population (e.g. people of Aboriginal, African, Asian Hispanic, or South Asian descent)
  • History of prediabetes (IGT or IFG or A1C 6.0 to 6.4%)
  • History of gestational diabetes mellitus
  • History of delivery of a macrosomic infant
  • Presence of end organ damage associated with diabetes:
    • Microvascular (retinopathy, neuropathy, nephropathy)
    • Macrovascular (coronary, cerebrovascular, peripheral)
  • Presence of vascular risk factors:
    • HDL cholesterol level <1.0 mmol/L in males, <1.3 mmol/L in females triglycerides ≥1.7 mmol/l
    • Hypertension
    • Overweight
    • Abdominal obesity
  • Presence of associated diseases:
  • Polycystic ovary syndrome
  • Acanthosis nigricans
  • Psychiatric disorders (bipolar disorder, depression, schizophrenia)
  • HIV infection
  • Obstructive Sleep Apnea (OSA)
  • Use of drugs associated with diabetes:
    • Glucocorticoids
    • Atypical antipsychotics
    • Highly Active Antiretroviral Therapy (HAART )
    • Other (see Appendix 1)
  • Other secondary causes (see Appendix 1)
  • Screen every 3 years in individuals ≥40 years of age
  • Screen every 3 years in individuals at high risk according to the CANRISK calculator
  • Screen earlier and/or more frequently in people with additional risk factors for diabetes (see below)
  • Screen earlier and/or more frequently in people at very high risk using the CANRISK calculator

Conditions that lead to misleading A1C include: hemoglobinopathies, hemolytic anemia, iron deficiency, severe renal or liver disease. Link to Table 1, Monitoring for Glycemic Control.

  1. Validated Assay: A1C must be measured using a validated assay standardized to the National Glycohemoglobin Standardization Program-Diabetes Control and Complications Trial reference.
  2. Ethnicity: Studies indicate that African Americans, American Indians, Hispanics and Asians have A1C values that are up to 0.4% higher than those of Caucasian patients at similar levels of glycemia (17,18). Research is required to determine if A1C levels differ in African Canadians or Canadian First Nations.
  3. Age: A1C values are affected by age, rising by up to 0.1% per decade of life (20,21). More studies may help to determine if age- or ethnic-specific adjusted A1C thresholds are required for diabetes diagnosis.
  4. Special Populations: A1C is not recommended for diagnostic purposes in children, adolescents, pregnant women or those with suspected type 1 diabetes.

Click here to view the Canadian Diabetes Risk Questionnaire (CANRISK) (printable and downloadable version)

Click here to view the Canadian Diabetes Risk Questionnaire (CANRISK) interactive online questionnaire

This is only to be used as a decision support tool and is subject to these terms.
For more information, please see terms of use.

*The Canadian Diabetes Association is the registered owner of the name Diabetes Canada. All content on, CPG Apps and in our online store remains exactly the same. For questions, contact