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. 2010 Jan;33(1):101-3.
doi: 10.2337/dc09-1366. Epub 2009 Oct 16.

A1C and diabetes diagnosis: The Rancho Bernardo Study

Caroline K Kramer  1 , Maria Rosario G Araneta, Elizabeth Barrett-Connor
Affiliations

A1C and diabetes diagnosis: The Rancho Bernardo Study

Caroline K Kramer et al. Diabetes Care. 2010 Jan.

Abstract

Objective: To examine the sensitivity and specificity of A1C as a diagnostic test for type 2 diabetes 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 A1C measured on the same day.

Results: Mean age of the 2,107 participants was 69.4 +/- 11.1 years; 43% were men. Based on the American Diabetes Association (ADA) criteria, 198 had previously undiagnosed type 2 diabetes. The sensitivity/specificity of A1C cut point of 6.5% was 44/79%. Results were similar in age- and sex-stratified analyses. Given the A1C cut point of 6.5%, 85% of participants were classified as nondiabetic by ADA criteria.

Conclusions: The limited sensitivity of the A1C test may result in delayed diagnosis of type 2 diabetes, while the strict use of ADA criteria may fail to identify a high proportion of individuals with diabetes by A1C > or =6.5% or retinopathy.

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Figures

Figure 1
Figure 1
A1C receiver operating characteristic curve for type 2 diabetes diagnosis: (A) whole cohort; (B) men (—) and women (---); and (C) by quartiles of age: first quartile (—), second quartile (---), third quartile (---), and fourth quartile (----).
See this image and copyright information in PMC

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