Table 1

HRs for 15-year incidence of type 2 diabetes according to HbA1c

HbA1c category
<5.00%5.00–5.49%5.50–5.99%6.00–6.49%
n11234531570
Cases of incident diabetes393120
Cases per 1,000 person-years1.91.97.825.8
HRs (95% CIs) in models with baseline variables*
Model 0Model 1Model 2Model 3
HbA1c category
 <5.00%1.00 (0.27–3.68)1.11 (0.30–4.14)1.18 (0.31–4.41)1.27 (0.34–4.79)
 5.00–5.49% (reference)1.001.001.001.00
 5.50–5.99%4.30 (2.05–9.03)3.79 (1.79–8.06)3.24 (1.50–6.98)3.21 (1.49–6.92)
 6.00–6.49%15.67 (7.13–34.47)12.50 (5.51–28.34)9.74 (4.21–22.56)9.26 (4.01–21.40)
 P value for trend<0.001<0.001<0.001<0.001
HbA1c (per 1% increase)11.00 (5.66–21.39)8.54 (4.21–17.31)6.08 (2.96–12.47)6.05 (2.90–12.60)
HRs (95% CIs) in models with updated variables
Model 0Model 1Model 2Model 3
HbA1c category
 <5.00%2.31 (0.39–13.92)2.55 (0.42–15.39)2.55 (0.42–15.58)2.43 (0.40–14.97)
 5.00–5.49% (reference)1.001.001.001.00
 5.50–5.9912.58 (3.83–41.30)11.62 (3.52–38.36)10.97 (3.30–36.47)11.43 (3.43–38.07)
 6.00–6.49%61.05 (18.23–204.4)52.82 (15.57–179.3)45.52 (13.1–158.0)46.72 (13.4–163.3)
 P value for trend<0.001<0.001<0.001<0.001
 HbA1c (per 1% increase)41.37 (18.79–91.07)36.82 (16.30–83.21)31.10 (13.31–72.7)32.24 (13.60–76.41)
  • Model 0 was unadjusted. Model 1 included age and sex. Model 2 included the variables in model 1 plus LDL and HDL cholesterol levels, log-transformed triglyceride levels, BMI, waist-to-hip ratio, hypertension, family history of diabetes, education, alcohol use, physical activity score, and smoking status. Model 3 included all variables in model 2 plus white blood cell count, hemoglobin, ferritin, and creatinine.

  • *Cox models in which HbA1c and other variables at baseline were used to predict diabetes in the 15-year follow-up.

  • †Cox models in which updated HbA1c and other variables were used to predict diabetes in subsequent 5-year follow-up periods (see text for details).