Table 2

Distribution of diabetes duration and A1C at metformin initiation and parsimonious logistic regression of the probability of secondary failure of metformin

Failed metformin (n = 748)Did not fail metformin (n = 1,051)Odds ratio95% CIP
Mean age*57.7 (12.3)59.2 (11.3)0.980.97–0.99<0.001
Duration of diabetes (months)†
    0–334.2%44.4%1.00
    4–1111.0%11.0%1.561.12–2.180.008
    12–2314.8%11.6%2.091.53–2.87<0.001
    24–3510.7%10.7%1.591.13–2.240.007
    >3629.3%22.3%2.21.68–2.87<0.001
A1C (%)†
    <7.020.5%30.9%1.00
    7.0–7.935.8%33.3%1.531.19–1.980.001
    8.0–8.917.9%14.9%1.731.27–2.35<0.001
    >9.025.8%20.8%2.041.54–2.72<0.001
Hosmer-Lemeshow χ28.30.405
c Statistic0.613
  • *P = 0.008.

  • †χ2 for distribution P < 0.001.