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ICES study finds diabetes testing has never been more common


More than three million Ontarians were tested for diabetes in 2005 according to a study out of the Institute for Clinical Evaluative Sciences (ICES).

The report, published online at BMC Health Services Research on February 27, 2009, looked at Ontario residents, 20 years and older from 1995 to 2005 (9.3 million people in 2005) without a current diagnosis of diabetes.

"Testing has never been more common but clinicians are increasingly using the hemoglobin A1c test, a test that is not recommended by specialists for the diagnosis of diabetes. Clinicians and patients alike may prefer the hemoglobin A1c test because there is no need for fasting and it can be used to guide treatment decisions in managing diabetes if it is diagnosed,” says Sarah Wilson, lead researcher.

The Canadian Diabetes Association recommends that adults aged 40 and older be tested for diabetes every three years or earlier and more often in the presence of diabetes risk factors. The recommended tests for diabetes screening are a blood glucose test and/or an oral glucose tolerance test. Neither the Canadian Diabetes Association nor the American Diabetes Association recommends the hemoglobin A1c test for the diagnosis of diabetes at present largely because of historical concerns about the reproducibility of its test results.

The study found:

  • In 2005, more than a third of the entire population of Ontario was tested for diabetes with a blood glucose test, a 28 percent increase from 1995.
  • In Ontarians aged 40 and older, nearly two-thirds were tested for diabetes over the three-year period.
  • There is infrequent use of a recommended diabetes diagnosis test: the oral glucose tolerance test. Less than one percent of Ontarians underwent this test in any year.
  • The hemoglobin A1c test, a test used for monitoring diabetes treatment, but not currently recommended for diabetes diagnosis increased 250 percent between 1995 and 2005 in people without diabetes.
  • If current trends continue, the hemoglobin A1c test may soon be ordered more frequently in non-diabetics than in diabetic patients, despite the fact that it is not currently recommended as a test for diabetes diagnosis.

Recent estimates suggest that 8.8 percent of Ontario adults have physician-diagnosed diabetes, which is up 69 percent from 1995. This increase has been attributed to a rise in type 2 diabetes cases, driven by an increase in obesity rates. However, greater screening for diabetes over the last decade may have also contributed to these findings. Earlier studies have suggested that up to one-third of all ‘true’ diabetes cases are undiagnosed. With increasing diabetes awareness and the recent publication of screening guidelines, the proportion of undiagnosed diabetes may have declined.

Author affiliations: ICES (Dr. Wilson, Dr. Lipscombe, Rosella, Dr. Manuel); Dalla Lana School of Public Health, University of Toronto (Dr. Wilson, Rosella, Dr. Manuel); Women’s College Hospital (Dr. Lipscombe); Department of Medicine, University of Toronto (Dr. Lipscombe).

The study “Trends in laboratory testing for diabetes in Ontario, Canada 1995–2005: a population-based study” will be published online at BMC Health Services Research in February 2009.

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.


Read the Journal Article