Routine screening for type 2 diabetes in adults at low and moderate risk is not recommended, although it is recommended for people at high and very high risk of the disease, state new diabetes screening guidelines published in CMAJ (Canadian Medical Association Journal). The guidelines suggest using a risk calculator and then screening based on the predicted risk of diabetes.
"These new guidelines bring precision and convenience with web-based risk calculators and nonfasting A1C to diabetes screening," states Dr. Kevin Pottie with coauthors. "Leveraging these tools will help improve health outcomes by empowering patients to take an active role in managing and modifying their own risk factors through interventions like diet and exercise."
The guidelines, based on the latest evidence including a large randomized trial published Oct. 4, 2012), are an update to the 2005 Canadian Task Force on Preventive Health Care guidelines. Aimed at physicians and policy-makers, the guidelines contain screening recommendations for type 2 diabetes in asymptomatic adults at low to moderate risk of diabetes as well as people at high and very high risk.
"The guidelines highlight the need to focus on people at high and very high risk as prevalence rates of diabetes increase. Even in this group there is little evidence that frequent screening is beneficial, especially for reducing mortality," added the task force, "There was no evidence to support routine screening with a blood test for type 2 diabetes among adults at low or moderate risk of diabetes. Screening this population may lead to overdiagnosis, inappropriate investigation and treatment, and unnecessary psychosocial and economic costs."
The guidelines recommend using the nonfasting A1C as the blood test to screen, which will enable physicians to screen and monitor using the same test and is easier for patients who will not need to fast for the test.
- Use a risk calculator to determine the risk level for the general population rather than apply a blood test across the board.
- No routine screening with blood tests for adults unless at high or very high risk of diabetes.
- For adults at high risk of diabetes, screen every 3-5 years using A1C blood test.
- For adults at very high risk of diabetes, screen annually using A1C blood test.
- The Finnish Diabetes Risk Score (FINDRISC) is the preferred tool for screening, and the Canadian Diabetes Risk Assessment Questionnaire (CANRISK) is an acceptable alternative.
In 2008/09, an estimated 2.4 million Canadians (6.8% of the population) had either type 1 or type 2 diabetes confirmed and another 480 000 (1.4%) did not know they had the disease. Diabetes is increasing in the population and significant increases are expected over the next 10 years. Diabetes has significant health consequences and is strongly associated with vascular disease. Applying the risk calculators with or without follow-up blood testing offers an opportunity for Canadians to address their overall risk profile for vascular disease, including diabetes.
In addition to the full guidelines, one-page information pieces and screening algorithms are available for both physicians and patients on the task force website: www.canadiantaskforce.ca
The Canadian Task Force on Preventive Health Care is an independent body of 14 primary care and prevention experts. The task force has been established by the Public Health Agency of Canada to develop clinical practice guidelines that support primary care providers in delivering preventive health care.
- Canadian Task Force on Preventive Health Care. Recommendations on screening for type 2 diabetes in adults. CMAJ, 2012; 184: 1687-1696 DOI: 10.1503/cmaj.120732
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