A1C to detect diabetes in healthy adults: When should we recheck?

Osamu Takahashi, University of Oxford
Andrew J. Farmer, University of Oxford
Takuro Shimbo, International Medical Centre of Japan
Tsuguya Fukui, St Luke's International Hospital
Paul P. Glasziou, Bond University

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Takahashi, O., Farmer, A.J., Shimbo, T., Fukui, T. & Glasziou, P.P. (2010). A1C to detect diabetes in healthy adults: When should we recheck? Diabetes care, 33(9), 2016-2017.

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© Copyright by the American Diabetes Association, 2010

Abstract

OBJECTIVE To evaluate the optimal interval for rechecking A1C levels below the diagnostic threshold of 6.5% for healthy adults.

RESEARCH DESIGN AND 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 (∼≤1%) with an A1C ≥6.5%.