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In 2008/09, an estimated 2.4 million Canadians (6.8%) had either type 1 or type 2 diabetes, and an additional 480 000 (1.4%) were unaware that they were affected. The most recent Canadian data indicate that, from 1998/99 to 2008/09, the prevalence of diagnosed diabetes increased by 70% (Figure 1). The greatest relative increase in prevalence was seen in the age groups 35–39 and 40–44 years, in which the proportion doubled. In 2008/09, almost 50% of people with newly diagnosed diabetes were 45–64 years old (Figure 2). Substantial increases in prevalence are projected over the next decade.1 Because type 1 diabetes is much less common than type 2 diabetes and is generally symptomatic, we focused on type 2 diabetes in these guidelines.

Laboratory values used to define the diagnosis of diabetes have become more inclusive over time2.6 (Appendix 1). In 2002, a new diagnostic category (now commonly known as prediabetes) was created to describe patients at very high risk of diabetes. More recently, glycated hemoglobin (herein referred to as A1C), which reflects an individual’s average plasma glucose level over the previous 2–3 months, has been accepted as an ilternative diagnostic test for type 2 diabetes.7,8 Long-term consequences of type 2 diabetes include microvascular (retinopathy, nephropathy, neuropathy) and macrovascular (stroke, myocardial infarction) complications. An estimated 65%–80% of people with diabetes will die of a cardiovascular event, many without prior signs or symptoms of cardiovascular disease. Type 2 diabetes is a prevalent and costly chronic illness that demands lifestyle interventions, effective monitoring and pharmacologic management. Management of risk factors, including physical inactivity, blood pressure and blood lipid levels as well as blood glucose levels, is required to prevent long-term complications. Uncertainties remain about how best to prevent diabetes, the relative benefits of population screening and risk assessment, the ideal frequency of screening in high-risk populations and the potential harms of screening. This document updates the 2005 Canadian Task Force on Preventive