Abstract

Objective: African American (AA) youth have lower insulin sensitivity than their American White (AW) peers, but the metabolic pathway(s) responsible for this remain unknown. FFAs are associated with insulin resistance through the Randle cycle. The present investigation determined if elevating FFA is more deleterious to insulin sensitivity in AA vs AW adolescents.

Research Design and Methods: Insulin sensitivity (3 h hyperinsulinemic-euglycemic clamp) was evaluated in 22 AA and 21 AW adolescents on two occasions: (i) infusion of normal saline (NS), or (ii) infusion of 20% Intralipid (IL).

Results: During IL infusion fasting insulin and C-peptide concentrations increased while fasting glucose and basal glucose turnover did not change in either group. Insulin sensitivity decreased similarly in AA (NS 7.65 ± 0.61 vs IL 5.15 ± 0.52 μmol/kg/min per pmol/L) and AW (NS 8.97 ± 0.85 vs IL 5.96 ± 0.56 μmol/kg/min per pmol/L) (P<0.001).

Conclusion: African American and AW adolescents respond to FFA elevation similarly through: 1) increased fasting insulin secretion to maintain fasting glucose homeostasis; 2) reduced peripheral glucose uptake and insulin resistance. Thus, AA adolescents are not more susceptible to FFA-induced insulin resistance than AW youth.