title: Prevalence of Prediabetes and Undiagnosed Diabetes in Canada (2007-2011) According to Fasting Plasma Glucose and HbA1c Screening Criteria.
abstract: OBJECTIVE
  To provide the first population-based estimates of prediabetes and undiagnosed type 2 diabetes prevalence in Canada.
  
  
  METHODS
  We combined two fasting subsamples of the Canadian Health Measures Survey, which were restricted to nonpregnant adults ≥20 years of age (N = 3,494). Undiagnosed diabetes was defined as not having self-reported type 2 diabetes but having blood glucose measures that met Canadian guidelines (i.e., fasting plasma glucose [FPG] level of ≥7.0 mmol/L or hemoglobin A1c [HbA1c] level of ≥6.5% [≥48 mmol/mol]). Prediabetes was defined as an FPG level of ≥6.1 and <7.0 mmol/L or an HbA1c level of ≥6.0% and <6.5% (≥42 and <48 mmol/mol). All estimates were weighted using survey sampling weights. CIs were calculated with the bootstrap method.
  
  
  RESULTS
  According to FPG levels, the prevalence of undiagnosed type 2 diabetes in Canadian adults was 1.13% (95% CI 0.79, 1.62), contributing to ∼20% of total type 2 diabetes prevalence (5.62 [95% CI 4.52, 6.95]). Compared with FPG levels, the undiagnosed prevalence was greater using HbA1c level as a criterion (3.09% [95% CI 1.97, 4.81]), ∼41% of the total number of cases of diabetes (7.55 [95% CI 5.98, 9.49]). The HbA1c-only criterion resulted in a threefold increase in prediabetes prevalence overall and a sixfold increase among females (FPG 2.22%, HbA1c 13.31%). Screening based on FPG only identified older undiagnosed case patients, with a mean age of 58.7 years (95% CI 59.9, 63.4). Similarly, using HbA1c identified younger individuals with prediabetes, with reduced BMI and waist circumference compared with FPG levels.
  
  
  CONCLUSIONS
  In this first study of a nationally representative sample with biospecimen measures, we found that the prevalence of undiagnosed type 2 diabetes and prediabetes was significantly higher using HbA1c levels compared with FPG levels. Further evaluation is needed to fully assess the impact of using the HbA1c criterion.
authors: Dalla Lana School of Public Health, Toronto, Ontario, Canada Public Health Ontario, Toronto, Ontario, Canada Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada laura.rosella@utoronto.ca.
authors: Laura C
authors: LC
authors: Rosella
authors: Public Health Ontario, Toronto, Ontario, Canada.
authors: Michael
authors: M
authors: Lebenbaum
authors: Public Health Ontario, Toronto, Ontario, Canada.
authors: Tiffany
authors: T
authors: Fitzpatrick
authors: Dalla Lana School of Public Health, Toronto, Ontario, Canada.
authors: Aleksandra
authors: A
authors: Zuk
authors: St. Michael's Hospital, Toronto, Ontario, Canada Institute of Health Management Policy and Evaluation, University of Toronto, Toronto, Ontario, Canada.
authors: Gillian L
authors: GL
authors: Booth
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000032:analysis*; D002170:Canada / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology*; D005215:Fasting / Q000097:blood; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D008403:Mass Screening / Q000379:methods / Q000592:standards; D008875:Middle Aged; D011236:Prediabetic State / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology*; D015995:Prevalence; D055105:Waist Circumference; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin