TABLE 1

Clinical and metabolic characteristics among young and older MZ and DZ twins

Young twins
Older twins
MZDZMZDZ
n (M/F)66 (36/30)44 (24/20)42 (22/20)44 (16/28)
Age (years)28.2 ± 1.827.5 ± 1.961.6 ± 2.662.0 ± 2.0
Birth weight (g)2,639.8 ± 90.12,561.8 ± 85.22,664.4 ± 72.42,703.4 ± 103.7
BMI (kg/m2)24.3 ± 0.523.8 ± 0.626.2 ± 0.726.1 ± 0.9
WHR0.85 ± 0.020.82 ± 0.020.90 ± 0.020.87 ± 0.02
FFM (kg)54.9 ± 1.954.3 ± 2.651.1 ± 2.749.4 ± 2.4
HGP
    Basal3.10 ± 0.083.04 ± 0.083.02 ± 0.083.10 ± 0.08
    Clamp1.49 ± 0.071.49 ± 0.061.57 ± 0.091.70 ± 0.14
Glucose disposal (Rd)
    Basal3.10 ± 0.083.01 ± 0.073.05 ± 0.083.14 ± 0.07
    Clamp12.2 ± 0.5311.0 ± 0.498.86 ± 0.59*10.84 ± 0.57
Glucose oxidation
    Basal2.17 ± 0.142.02 ± 0.151.82 ± 0.191.75 ± 0.13
    Clamp4.72 ± 0.194.54 ± 0.293.88 ± 0.264.27 ± 0.21
Fat oxidation
    Basal1.25 ± 0.061.32 ± 0.071.36 ± 0.081.52 ± 0.07
    Clamp0.32 ± 0.050.38 ± 0.090.56 ± 0.070.58 ± 0.08
Glycolytic flux
    Basal1.62 ± 0.132.00 ± 0.192.11 ± 0.172.28 ± 0.20
    Clamp4.49 ± 0.294.37 ± 0.303.80 ± 0.304.01 ± 0.42
NOGM
    Basal0.93 ± 0.120.99 ± 0.141.22 ± 0.171.42 ± 0.12
    Clamp7.53 ± 0.466.41 ± 0.424.99 ± 0.52*6.67 ± 0.52
Exogenous glucose storage
    Basal1.48 ± 0.141.01 ± 0.200.94 ± 0.140.86 ± 0.18
    Clamp7.75 ± 0.446.59 ± 0.495.06 ± 0.53*6.83 ± 0.55
Insulin secretion (Di)2.11E-7 ± 1.14E-72.32E-7 ± 1.39E-71.10E-7 ± 0.78E-71.32E-7 ± 0.92E-7
  • Data are means ± SE. All metabolic turnover rates are expressed as mg · kg FFM−1 · min−1.

  • *

    * P < 0.05 for MZ vs. DZ within same age-group. FFM, fat-free mass; WHR, waist-to-hip ratio.