A1C to detect diabetes in healthy adults: when should we recheck?
OBJECTIVE
To evaluate the optimal interval for rechecking A1C levels below the diagnostic threshold of 6.5% for healthy adults.


METHODS
This was a retrospective cohort study. Participants were 16,313 apparently healthy Japanese adults not taking glucose-lowering medications at baseline. Annual A1C measures from 2005 to 2008 at the Center for Preventive Medicine, a community teaching hospital in Japan, estimated cumulative incidence of diabetes.


RESULTS
Mean age (+/-SD) of participants was 49.7 +/- 12.3 years, and 53% were male. Mean A1C at baseline was 5.4 +/- 0.5%. At 3 years, for those with A1C at baseline of <5.0%, 5.0-5.4%, 5.5-5.9%, and 6.0-6.4%, cumulative incidence (95% CI) was 0.05% (0.001-0.3), 0.05% (0.01-0.11), 1.2% (0.9-1.6), and 20% (18-23), respectively.


CONCLUSIONS
In those with an A1C <6.0%, rescreening at intervals shorter than 3 years identifies few individuals (approximately <or=1%) with an A1C >or=6.5%.
Takahashi
Osamu
O
Department of Primary Health Care, University of Oxford, Oxford, U.K. otakahas@luke.or.jp
Farmer
Andrew J
AJ
Shimbo
Takuro
T
Fukui
Tsuguya
T
Glasziou
Paul P
PP
D000328:Adult; D003920:Diabetes Mellitus / Q000175:diagnosis* / Q000378:metabolism*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
D006442:Glycated Hemoglobin