Hemoglobin A1c in predicting progression to diabetes☆

Abstract 

The predictive value of hemoglobin A1c (HbA1c) in comparison to fasting plasma glucose (FPG) is evaluated for 5-year incident diabetes (DM), as HbA1c may be more practical than FPG in the screening for DM in the future. Of 1189 non-DM subjects aged 35–89 years old from the Funagata Study, 57 subjects (4.8%) had developed DM on the WHO criteria at 5-year follow-up. The odds ratio (95% confidence interval: CI) for a one standard deviation increase in FPG/HbA1c was 3.40 (2.44–4.74)/3.49 (2.42–5.02). The area under the receiver operating characteristic curve for FPG/HbA1c was 0.786 (95% CI: 0.719–0.853)/0.785 (0.714–0.855). The HbA1c corresponding to FPG 5.56mmol/l was HbA1c 5.3%. There was no statistical difference in sensitivity between FPG 5.56mmol/l and HbA1c 5.3% (61.4% vs. 56.1%), while specificity was higher in HbA1c 5.3% than FPG 5.56mmol/l (87.8% vs. 82.5%, p-value<0.001). The fraction of incident case from those with baseline IGT was similar between the groups, however the fraction of people above the cut-off was significantly lower in HbA1c 5.3% than FPG 5.56mmol/l (14.3% vs. 19.6%, p-value<0.001). HbA1c is similar to FPG to evaluate DM risk, and HbA1c could be practical and efficient to select subjects for intervention.

Abbreviations: ADA, American Diabetes Association, CI, confidence intervals, BMI, body mass index, DM, diabetes mellitus, FPG, fasting plasma glucose, HbA1c, hemoglobin A1c, IGT, impaired glucose tolerance, JDS, Japan Diabetes Society, OGTT, oral glucose tolerance test, OR, odds ratio, ROC, receiver operating characteristic, Wc, Waist circumference, WHO, World Health Organization, 2h PG, 2h plasma glucose

Keywords: Diabetes mellitus, Fasting plasma glucose, Hemoglobin A1c, Incidence, Impaired glucose tolerance