A1C and diabetes diagnosis: The Rancho Bernardo Study.
OBJECTIVE
To examine the sensitivity and specificity of A1C as a diagnostic test for type 2 diabetes in older adults.


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.
Kramer
Caroline K
CK
Division of Epidemiology, Department of Family and Preventive Medicine, University of California, San Diego, La Jolla, California, USA. ebarrettconnor@ucsd.edu
Araneta
Maria Rosario G
MR
Barrett-Connor
Elizabeth
E
D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis* / Q000378:metabolism*; D005260:Female; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged
D006442:Glycated Hemoglobin