Table 1.

Correlations of C-peptide levels and breast density with measures of adiposity (n = 1,499)

Measures of adiposityC-peptide (ng/mL)Breast density (%)
BMI (kg/m2), type of adjustment
    Covariates 1*0.330 (<0.0001)−0.497 (<0.0001)
    Covariates 20.314 (<0.0001)−0.488 (<0.0001)
    Covariates 1 + WHR0.173 (<0.0001)−0.389 (<0.0001)
    Covariates 2 + WHR0.161 (<0.0001)−0.383 (<0.0001)
WHR, type of adjustment
    Covariates 1*0.374 (<0.0001)−0.361 (<0.0001)
    Covariates 20.362 (<0.0001)−0.351 (<0.0001)
    Covariates 1 + BMI (kg/m2)0.252 (<0.0001)−0.142 (<0.0001)
    Covariates 2 + BMI (kg/m2)0.246 (<0.0001)−0.134 (<0.0001)
  • NOTE: Spearman correlation between continuous variables (P). Adjusted correlations are partial Spearman coefficients.

  • * Adjusted for age (y). Associations with C-peptide levels are also adjusted for time since last meal (≤2, >2-3, >3-4, >4-5, >5 h).

  • Adjusted for age (y), alcohol (drinks/wk) and total energy (kcal/d) intakes in the past year, menopausal status (premenopausal or postmenopausal), age at menarche (y), age at first full-term pregnancy (y), lactation (y), number of full-term pregnancies, number of personal breast biopsies, duration of past use of oral contraceptive and of hormone replacement therapy (y), family history of breast cancer in first-degree relative (yes/no), physical activity (METs h/wk), education (primary or less, secondary, college, or university diploma), and smoking status (never, former, or current smoker). Associations with C-peptide levels are also adjusted for time since last meal (≤2, >2-3, >3-4, >4-5, >5 h). Analysis are restricted to n = 1,474 due to missing values for some breast cancer risk factors among participants.