Effect of age and race/ethnicity on HbA1c levels in people without known diabetes mellitus: implications for the diagnosis of diabetes.
OBJECTIVE
To determine if age and race/ethnicity affect HbA1c levels independent of glycemia.


METHODS
We analyzed 2712 individuals from the NHANES III population 40-74 years old without diabetes history.


RESULTS
HbA1c levels increased by 0.10% per decade in people with NGT and 0.07% in those with IFG and/or IGT, independent of fasting and 2-h glucose on OGTT's. Compared to non-Hispanic whites, HbA1c levels increased by 0.12% (NGT) and 0.10% (IFG/IGT) in Mexican-Americans and 0.21% (NGT) and 0.35% (IFG/IGT) in non-Hispanic blacks, independent of glycemia. At HbA1c levels of >or=6.5%, >or=7.0% and 6.5-6.9%, diabetes diagnosed by current FPG/OGTT criteria occurred in 82%, 94% and 65%, respectively. In non-Hispanic blacks with HbA1c levels of 6.5-6.9%, 68% of those 40-74 years old and 87% of those over 64 years old would not have diabetes by FPG/OGTT criteria. Over 90% of all race/ethnicity groups would have diabetes with HbA1c levels >or=7.0%.


CONCLUSIONS
Because many people, especially older non-Hispanic blacks, with HbA1c levels of 6.5-6.9% would not have diabetes by current FPG/OGTT criteria and clinical retinopathy and nephropathy are very unusual in patients whose HbA1c levels are kept <7.0%; we recommend an HbA1c level of >or=7.0% to diagnose diabetes.
Davidson
Mayer B
MB
Clinical Center for Research Excellence, Charles Drew University, 1731 East 120th Street, Los Angeles, CA 90059, United States. mayerdavidson@cdrewu.edu <mayerdavidson@cdrewu.edu>
Schriger
David L
DL
D000328:Adult; D001741:Black or African American; D000367:Age Factors; D000368:Aged; D003920:Diabetes Mellitus / Q000097:blood / Q000175:diagnosis* / Q000208:ethnology*; D005260:Female; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006306:Health Surveys; D006630:Hispanic or Latino; D006801:Humans; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D044469:Racial Groups; D012044:Regression Analysis; D012737:Sex Factors; D044465:White People
D006442:Glycated Hemoglobin