Journal of General Internal Medicine

, Volume 23, Issue 9, pp 1346–1353

Value of Risk Stratification to Increase the Predictive Validity of HbA1c in Screening for Undiagnosed Diabetes in the US Population

  • Adit A. Ginde
  • Enrico Cagliero
  • David M. Nathan
  • Carlos A. CamargoJr.
Original Article

DOI: 10.1007/s11606-008-0661-6

Cite this article as:
Ginde, A.A., Cagliero, E., Nathan, D.M. et al. J GEN INTERN MED (2008) 23: 1346. doi:10.1007/s11606-008-0661-6



Opportunistic screening using hemoglobin A1c (HbA1c) may improve detection of undiagnosed diabetes but remains controversial.


To evaluate the predictive validity of HbA1c as a screening test for undiagnosed diabetes in a risk-stratified sample of the US population.


Weighted cross-sectional analysis of diabetes risk factors, HbA1c, and fasting plasma glucose (FPG) in National Health and Nutrition Examination Survey (NHANES), 1999–2004.


Six thousand seven hundred and twenty-three NHANES participants from morning examination session, aged ≥18 years and without prior physician-diagnosed diabetes.


HbA1c and undiagnosed diabetes defined by FPG ≥ 7.0 mmol/l (126 mg/dl).


The estimated prevalence of undiagnosed diabetes in the US population was 2.8% (5.5 million people). HbA1c had strong correlation with undiagnosed diabetes, with an area under the receiver-operating characteristic curve of 0.93. Independent predictors of undiagnosed diabetes were older age, male sex, black race, hypertension, elevated waist circumference, elevated triglycerides, and low high-density lipoprotein cholesterol. We derived a risk score for undiagnosed diabetes and stratified participants into low (0.44% prevalence), moderate (4.1% prevalence), and high (11.1% prevalence) risk subgroups. In moderate and high risk groups, a threshold HbA1c value ≥ 6.1% identified patients requiring confirmatory FPG; HbA1c ≤ 5.4% identified patients for whom diabetes could be reliably excluded. Intermediate HbA1c (5.5–6.0%) may exclude diabetes in moderate, but not high risk groups).


Risk stratification improves the predictive validity of HbA1c in screening for undiagnosed diabetes in the US population. Although opportunistic screening with HbA1c would improve detection of undiagnosed diabetes, cost-effectiveness studies are needed before implementation of specific screening strategies using HbA1c.

Key words

diabetes mellitus glycohemoglobin screening validity NHANES 

Copyright information

© Society of General Internal Medicine 2008

Authors and Affiliations

  • Adit A. Ginde
    • 1
    • 2
  • Enrico Cagliero
    • 3
  • David M. Nathan
    • 3
  • Carlos A. CamargoJr.
    • 4
  1. 1.Department of Emergency MedicineUniversity of Colorado Denver School of MedicineAuroraUSA
  2. 2.Department of Emergency MedicineBeth Israel Deaconess Medical CenterBostonUSA
  3. 3.Diabetes CenterMassachusetts General HospitalBostonUSA
  4. 4.Department of Emergency MedicineMassachusetts General HospitalBostonUSA

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