African American (AA) children have lower hepatic insulin clearance than European Americans (EA), as obtained with a 25-sample intravenous glucose tolerance test (FSIGT), over 240 minutes (t=0, 2, 3, 4 5, 6, 8, 10, 12, 15, 19, 20, 21, 22, 24, 26, 28, 30, 35, 40, 50, 60, 70, 180, 240 minutes). C-peptide and insulin concentrations were analyzed with a recent model of hepatic (FEL) and extra-hepatic (CLP) insulin clearance. This model has not been tested in a reduced sampling protocol, easier to be performed in larger cohorts. With data from 203 children of both sexes and 3 ethnic groups [55 AA, 88 EA, 60 HA (Hispanic Americans), age 7-13 years, mean BMI = 19 kg/m2, basal plasma glucose = 99 mg/dL, insulin = 78 pmol/L, C-peptide = 511 pmol/L], a reduced 12-sample schedule was examined (t=0, 2, 4, 8, 19, 22, 26, 30, 40, 50, 70, 180 minutes). FEL and CLP from the reduced protocol were strongly correlated with the full one: FEL: r=0.91, p<0.001; CLP: r=0.96, p<0.001. The mean precision of estimates (coefficient of variation, CV) was similar: CVfull=40%, CVreduced=41%. The lower hepatic but not extra-hepatic insulin clearance in AA vs. EA children was still detectable with the reduced sampling (see Figure 1), that provides virtually identical and precise estimates of insulin clearance. This reduced protocol can be used in larger population-based studies.

F. Piccinini: None. B. Gower: None. J.R. Fernandez: None. R.N. Bergman: Consultant; Self; Zafgen, Inc.


National Institute of Diabetes and Digestive and Kidney Diseases (DK067426); Nutrition Obesity Research Center (DK56336); National Institutes of Health (M01RR00032)

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