Use of haemoglobin A1c to detect impaired fasting glucose or Type 2 diabetes in a United Kingdom community based population

B. Kumaravel, M.O. Bachmann, N. Murray, K. Dhatariya, M. Fenech, W.G. John, Tracey Scarpello, M.J. Sampson

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Abstract

Aims: To evaluate the diagnostic accuracy of haemoglobin A1c (HbA1c) in screening for impaired fasting glucose and Type 2 diabetes (T2DM). Methods: We screened 3904 adults aged 45-70 (mean age 58.6 [standard deviation (SD) 6.9] years, mean body mass index (BMI) 29.9 [SD 4.7]kg/m ), with fasting plasma glucose (FPG) and HbA1c as part of a large diabetes prevention programme. We assessed the diagnostic accuracy of HbA1c for predicting impaired fasting glucose (IFG), (defined either as FPG 5.6-6.9mmol/l, or 6.1-6.9mmol/l), and T2DM (FPG=7.0mmol/l). Results: The prevalences of IFG were 13.8% (FPG 5.6-6.9. mmol/l) and 4.5% (FPG 6.1-6.9. mmol/l) and of T2DM was 2.1%. Using FPG 5.6-6.9. mmol/l as the IFG reference standard, HbA1c of 39-47. mmol/mol (5.7-6.4%) was 63% sensitive and 81% specific, and HbA1c 43-47. mmol/mol (6.1-6.4%) was 21% sensitive and 98% specific, in diagnosing IFG. HbA1c = 48 mmol/mol (6.5%) was 61% sensitive and 99% specific in diagnosing T2DM. Having HbA1c 39-47. mmol/mol (5.7-6.4%), male sex, and body mass index >29.5 together increased the odds of IFG 6.5-fold (95% confidence interval (CI) 5.5-7.8) compared to the pre-test odds. Conclusion: Defining 'pre-diabetes' at a lower HbA1c threshold of 39. mmol/mol (5.7%) instead of 47. mmol/mol (6.1%) increases its sensitivity in diagnosing IFG, but current American Diabetes Association definitions of 'pre-diabetes' based on HbA1c would fail to detect almost 40% of people currently classified as IFG. This has implications for current and future diabetes prevention programmes, for vascular risk management, and for clinical advice given to people with 'pre-diabetes' based on fasting glucose data. © 2011 Elsevier Ireland Ltd.
Original languageEnglish
Pages (from-to)211-216
Number of pages6
JournalDiabetes Research and Clinical Practice
Volume96
Issue number2
DOIs
Publication statusPublished - 1 May 2012

Keywords

  • Humans
  • Aged
  • Middle Aged
  • Fasting
  • Male
  • Great Britain
  • Female
  • Blood Glucose

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