TABLE 2

Incidence rate of microalbuminuria (per 100 person-years) according to HbA1c value during different intervals preceding follow-up (different windows of exposure)

Interval preceding follow-upHbA1c value (%)
Onsets (n)Person-Years (n)χ2P
4.3–7.27.3–8.18.2–9.09.1–16.5
1st and 2nd years1.31.53.16.9993,01355.81.3 × 10−9
3rd and 4th years2.22.22.26.41023,08234.94.7 × 10−6
1st to 4th years1.41.73.06.5922,88644.81.6 × 10−7
  • Data are percentages or n. Detailed definitions of the intervals (exposure windows) are included in research design and methods. Ranges shown for HbA1c values are the quartiles of the distribution of HbA1c values during baseline (see Table 1). The quartile ranges of HbA1c were almost identical in all three windows. Numbers for onsets and person-years vary because of missing data on HbA1c during one or both 2-year intervals for a few patients. When all three models were restricted to the subgroup with HbA1c values for both intervals, P values were 1.0 × 10−8, 1.3 × 10−6, and 1.6 × 10−7.