Table 2

Sensitivity, specificity, and positive and negative predictive value of increasing A1C cutoff levels for detecting undiagnosed diabetes and for predicting the incidence of type 2 diabetes at the 6-year follow-up

A1C cutoff (%)Baseline undiagnosed diabetesIncident diabetes after 6 years of follow-up
Predictive valuePredictive value
SensitivitySpecificityPositiveNegativeSensitivitySpecificityPositiveNegative
5.0 (−1.00 SDs above normal mean)0.9720.1150.0740.9820.9620.1210.1620.947
5.1 (−0.75 SDs above normal mean)0.9560.1850.0790.980.9350.1980.1710.945
5.2 (−0.50 SDs above normal mean)0.9450.2790.0870.9860.8860.3020.1840.937
5.3 (−0.25 SDs above normal mean)0.9150.3900.0980.9840.8270.4190.2010.932
5.4 (0.00 SDs above normal mean)0.8870.5060.1150.9840.7680.5470.2310.930
5.5 (0.25 SDs above normal mean)0.8660.6160.1410.9840.6820.6650.2650.922
5.6 (0.50 SDs above normal mean)0.8220.7170.1740.9820.5940.7690.3130.914
5.7 (0.75 SDs above normal mean)0.7700.7970.2160.9790.5080.8470.3700.907
5.8 (1.00 SDs above normal mean)0.7200.8620.2740.9770.4200.9080.4480.898
5.9 (1.25 SDs above normal mean)0.6760.9070.3440.9750.3330.9470.5270.889
6.0 (1.50 SDs above normal mean)0.6190.9350.4110.9710.2630.9670.5860.881
6.2 (2.00 SDs above normal mean)0.5230.9680.5440.9650.1520.9870.6770.868
6.6 (3.00 SDs above normal mean)0.3720.9920.7710.9560.0510.9990.8850.856