TABLE 2

Multiple logistic regression analysis of measures of β-cell function and 5-year risk of type 2 diabetes in IRAS, adjusted for age, sex, ethnicity, and clinic

Independent variableStratification variableAdjusted for age, sex, ethnicity, and clinic
Interaction term
OR*95% CIχ2P value
AIR
Ethnicity
 NHW0.250.12–0.5313.10.45
 Black0.420.20–0.748.9
 Hispanic0.390.24–0.6413.6
OGTT
 NGT0.550.34–0.896.0§0.31
 IGT0.400.25–0.6414.4
Waist
 <Median0.280.14–0.5513.60.46
 ≥Median0.340.23–0.5028.4
S1
 <Median0.410.29–0.5727.20.01
 ≥Median0.120.04–0.3713.3
Intact PI
Ethnicity
 NHW3.822.51–5.8438.70.002
 Black1.381.02–1.864.3§
 Hispanic1.601.22–2.1011.4
OGTT
 NGT2.211.63–3.0225.60.014
 IGT1.351.07–1.696.7
Waist
 <Median2.431.45–4.0711.30.35
 ≥Median1.621.32–2.0020.5
S1
 <Median1.481.22–1.7815.30.49
 ≥Median2.681.53–4.7012.0
Split PI
Ethnicity
 NHW3.062.12–4.4235.60.07
 Black1.381.05–1.815.5
 Hispanic1.941.42–2.6517.2
OGTT
 NGT1.901.48–2.4425.20.33
 IGT1.551.21–1.9812.1
Waist
 <Median1.911.23–2.978.20.81
 ≥Median1.761.44–2.1530.2
S1
 <Median1.611.34–1.9425.10.96
 ≥Median2.101.11–3.975.2§
Insulin
Ethnicity
 NHW2.801.79–4.3820.50.28
 Black1.130.83–1.530.6
 Hispanic1.751.23–2.4510.6
OGTT
 NGT1.861.32–2.6412.30.12
 IGT1.260.99–1.593.6
Waist
 <Median1.390.90–2.162.20.79
 ≥Median1.491.14–1.938.8
S1
 <Median1.661.25–2.2112.30.02
 ≥Median0.950.59–1.520.6
  • Analyses were stratified by potential effect-modifying variables, including ethnicity, baseline IGT, baseline abdominal adiposity, and baseline insulin resistance.

  • *

    * ORs refer to risk associated with a 1 SD increase in the independent variable.

  • P < 0.001;

  • P < 0.01;

  • §

    § P < 0.05;

  • P < 0.0001. Definition of strata of potential effect modifiers: ethnicity (non-Hispanic white [NHW], black, Hispanic [His]), IGT (no/yes), abdominal adiposity (less than versus equal to or greater than the sex-specific median for waist circumference [males = 94 cm, females = 85 cm]), and insulin resistance (less than versus equal to or greater than the median for S1 [1.64 min · μU−1 · ml−1]).