Type 2 diabetes (2012)
Guideline Update
The guideline was updated to incorporate evidence from a large randomized controlled trial published on October 4, 2012, two weeks before the print version of our recommendations. Although the electronic version of the Task Force's guideline, available on the Canadian Medical Association Journal (CMAJ) website, was corrected, the version included in the October 16, 2012 print issue of CMAJ was already at press when the new trial was published and is out of date.
A corrected reprint was mailed to CMAJ subscribers on November 6, 2012.
Summary of recommendations for clinicians and policy-makers
These recommendations concern screening for type 2 diabetes in asymptomatic adults. They do not apply to people who have symptoms of diabetes or to those at risk of developing type 1 diabetes.
The Task Force will continue to closely monitor scientific developments regarding diabetes screening and, within the next 5 years, will share its reflections with Canadians by publishing an update to the 2012 guideline.
Recommendations
For adults at low to moderate risk of diabetes (as determined using a validated risk calculator1 2), we recommend not routinely screening for type 2 diabetes.
(Weak recommendation; low quality evidence)
For adults at high risk of diabetes (as determined using a validated risk calculator1 2), we recommend routine screening every 3-5 years using the A1C blood test3.
(Weak recommendation; low quality evidence)
For adults at very high risk of diabetes (as determined using a validated risk calculator1 2), we recommend routine screening every year using the A1C blood test3.
(Weak recommendation; low quality evidence)
Additional Documents
NOTES
10-year risk of developing diabetes:
- Low risk: 1 in 100 to 1 in 25 = 1% to 4%
- Moderate risk: 1 in 6 = 17%
- High risk: 1 in 3 = 33%
- Very high risk: 1 in 2 = 50%
For adults aged ≥ 18 years, we recommend calculating risk at least once every 3-5 years (or when risk factors are present, e.g., obesity & hypertension).
1 The FINDRISC (Finnish Diabetes Risk Score) questionnaire was selected as the preferred validated risk calculator, but the CANRISK (Canadian Diabetes Risk Assessment Questionnaire) is a second option. Factors considered in these two questionnaires include age, obesity, history of elevated blood glucose, history of hypertension, family history of diabetes, low activity levels, and limited consumption of fruits and vegetables. The CANRISK questionnaire can be accessed via the Task Force website or the PHAC website.
2 The hemoglobin A1C blood test was selected as the preferred test, but fasting blood glucose measurement and the glucose tolerance test are considered other acceptable options. A hemoglobin A1C measurement of 6.5% or higher is the recommended cut-off for a diagnosis of diabetes, but a value below 6.5% does not rule out diabetes diagnosed through blood glucose testing. Hemoglobin A1C should be measured using a standardized and validated assay.