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 ± 0.5 | 4.1 ± 0.6 | 6.3 ± 0.6 | H versus C: P = 0.05; AA versus C: P = 0.02 |
| Fasting insulin (μIU/ml) | 7.4 ± 1.0 | 10.4 ± 1.43 | 9.1 ± 1.4 | H versus AA: P = 0.001; H versus C: P = 0.04 |
| Fasting free fatty acids (mmol) | 0.39 ± 0.02 | 0.41 ± 0.02 | 0.36 ± 0.02 | None |
| AIR (μIU/ml) | 938 ± 85 | 1,210 ± 116 | 747 ± 122 | AA versus H: P = 0.06; AA versus C: P = 0.003 |
| DI from AIR (min−1) | 0.35 ± 0.05 | 0.45 ± 0.07 | 0.29 ± 0.07 | None |
| Glucose effectiveness (% per min) | 0.025 ± 0.001 | 0.027 ± 0.002 | 0.027 ± 0.002 | None |
| GEZI (% per min) | 0.023 ± 0.001 | 0.023 ± 0.002 | 0.023 ± 0.001 | None |
| First-phase insulin secretion (nmol/min) | 153 ± 18 | 123 ± 24 | 112 ± 25 | None |
| Second-phase insulin secretion (nmol/min) | 289 ± 41 | 200 ± 53 | 206 ± 56 | AA versus H: P = 0.03 |
| Total insulin secretion (adj for insulin sensitivity) | 436 ± 53 | 302 ± 71 | 354 ± 76 | AA versus C: P = 0.08; AA versus H: P = 0.03 |
| DI from secretion (min−1) | 34.3 ± 3.0 | 23.1 ± 3.9 | 34.7 ± 4.1 | AA versus C: P = 0.04; AA versus H: P = 0.03 |
| Hepatic insulin extraction (%) | 47.3 ± 2.2 | 36.6 ± 2.9 | 49.1 ± 3.0 | AA versus H: P = 0.006 AA versus C: P = 0.004 |
| Fractional disappearance of insulin (% per min) | 26.0 ± 1.1 | 20.9 ± 1.5 | 24.2 ± 1.5 | AA 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.