Table 2—

Least-square mean differences in insulin action and secretion parameters for three ethnic groups

Hispanic (n = 28)African-Americans (n = 15)Caucasians (n = 14)Significant effects
Insulin sensitivity [× 10−4 min−1/(μIU/ml)]4.5 ± 0.54.1 ± 0.66.3 ± 0.6H versus C: P = 0.05; AA versus C: P = 0.02
Fasting insulin (μIU/ml)7.4 ± 1.010.4 ± 1.439.1 ± 1.4H versus AA: P = 0.001; H versus C: P = 0.04
Fasting free fatty acids (mmol)0.39 ± 0.020.41 ± 0.020.36 ± 0.02None
AIR (μIU/ml)938 ± 851,210 ± 116747 ± 122AA versus H: P = 0.06; AA versus C: P = 0.003
DI from AIR (min−1)0.35 ± 0.050.45 ± 0.070.29 ± 0.07None
Glucose effectiveness (% per min)0.025 ± 0.0010.027 ± 0.0020.027 ± 0.002None
GEZI (% per min)0.023 ± 0.0010.023 ± 0.0020.023 ± 0.001None
First-phase insulin secretion (nmol/min)153 ± 18123 ± 24112 ± 25None
Second-phase insulin secretion (nmol/min)289 ± 41200 ± 53206 ± 56AA versus H: P = 0.03
Total insulin secretion (adj for insulin sensitivity)436 ± 53302 ± 71354 ± 76AA versus C: P = 0.08; AA versus H: P = 0.03
DI from secretion (min−1)34.3 ± 3.023.1 ± 3.934.7 ± 4.1AA versus C: P = 0.04; AA versus H: P = 0.03
Hepatic insulin extraction (%)47.3 ± 2.236.6 ± 2.949.1 ± 3.0AA versus H: P = 0.006 AA versus C: P = 0.004
Fractional disappearance of insulin (% per min)26.0 ± 1.120.9 ± 1.524.2 ± 1.5AA versus H: P = 0.009
  • Data are least-square means ± standard error after adjusting for Tanner stage and total fat mass; the model for AIR also adjusted for insulin sensitivity; analysis was conducted on log-transformed data, but means are presented for non–log-transformed data for ease of interpretation. AIR, acute insulin response; DI, disposition index; GEZI, glucose effectiveness at zero insulin; H, Hispanic; C, Caucasian; AA, African-American.