TABLE 2

Intraclass correlations for metabolic variables in MZ and DZ young and older twins

Young
Old
MZDZPMZDZP
Insulin secretion (Di)0.75 (0.56–0.86)0.30 (−0.10–0.59)<0.0010.84 (0.67–0.92)0.60 (0.27–0.79)<0.01
HGP
    Basal0.29 (−0.01 to 0.53)0.07 (−0.45 to 0.53)0.250.55 (0.16–0.77)0.53 (0.19–0.74)0.89
    Clamp*
Glucose disposal (Rd)
    Basal0.27 (0.06–0.44)0.13 (−0.35 to 0.50)0.470.67 (0.47–0.80)0.34 (0.08–0.55)0.02
    Clamp0.53 (0.26–0.71)0.31 (−0.21 to 0.64)0.180.56 (0.17–0.77)0.24 (−0.17 to 0.55)0.054
Glycolytic flux
    Basal*
    Clamp0.28 (−0.02 to 0.53)0.58 (0.13–0.78)0.31 (−0.46 to 0.69)−0.18 (−0.46 to 0.14)
Glucose oxidation
    Basal*
    Clamp*
NOGM
    Basal*−0.27 (−0.53 to 0.07)−0.16 (−0.53 to 28)0.04 (−0.32 to 0.38)−0.33 (−0.65 to 0.17)
    Clamp0.49 (0.22–0.69)0.31 (−0.22 to 0.64)0.280.48 (0.02–0.73)0.10 (−0.29 to 0.44)0.03
Exogenous glucose storage
    Basal0.14 (−0.24 to 0.46)0.24 (−0.16 to 0.54)−0.18 (−0.58 to 0.35)−0.05 (−0.38 to 0.30)
    Clamp0.26 (−0.07 to 0.53)0.33 (−0.13 to 0.63)0.62 (0.25–0.80)0.26 (−0.13 to 0.57)0.02
Fat oxidation
    Basal*−0.63 (−0.78 to −0.37)−0.26 (−0.58 to 0.15)−0.22 (− 0.55 to 0.20)−0.41 (−0.68 to 0.02)
    Clamp−0.24 (− 0.54 to 0.14)0.31 (−0.06 to 0.59)−0.01 (−0.41 to 0.39)−0.44 (−0.69 to −0.06)
  • Data are correlation coefficients (95% CI) adjusted for sex. P value expresses the significance level for comparisons of MZ and DZ twin within each age-group.

  • *

    * Do not fulfill conditions for biometric modeling;

  • double entry of data.