Hemoglobin A1C and diabetes diagnosis: The Rancho Bernardo Study
- Caroline K Kramer, MD1,2,
- Maria Rosario G. Araneta, PhD1 and
- Elizabeth Barrett-Connor, MD (ebarrettconnor{at}ucsd.edu)1
- 1Division of Epidemiology, Department of Family and Preventive Medicine, University of California, San Diego, La Jolla, California
- 2Division of Endocrinology, Hospital de Clinicas de Porto Alegre, RS, Brazil
Abstract
Objective: To examine the sensitivity and specificity of hemoglobin A1c (HbA1c) as a diagnostic test for type 2 diabetes mellitus (T2DM) in older adults.
Research design and methods: Cross-sectional study of community-dwelling adults without known diabetes who had an oral glucose tolerance test and HbA1c measured on the same day.
Results: Mean age of the 2107 participants was 69.4±11.1 yrs; 43% were men. Based on ADA criteria, 198 had previously undiagnosed T2DM. The sensitivity/specificity of HbA1c cut point of 6.5% was 44/79%. Results were similar in age and sex-stratified analyses. Given the HbA1c cut point of 6.5%, 85% of participants were classified as non-diabetic by ADA criteria.
Conclusion: The limited sensitivity of the HbA1c test may result in delayed diagnosis of T2DM, while the strict use of ADA criteria may fail to identify a high proportion of individuals with diabetes by HbA1c ≥6.5% or retinopathy.
Footnotes
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- Received July 24, 2009.
- Accepted October 6, 2009.
- Copyright © American Diabetes Association
