Effects of an intravenous lipid challenge and free fatty acid elevation on in vivo insulin sensitivity in African American versus Caucasian adolescents.
OBJECTIVE
African American youth have lower insulin sensitivity than their Caucasian peers, but the metabolic pathways responsible for this difference remain unknown. Free fatty acids (FFAs) are associated with insulin resistance through the Randle cycle. The present investigation determined whether elevating FFA is more deleterious to insulin sensitivity in African American than in Caucasian adolescents.


METHODS
Insulin sensitivity (3-h hyperinsulinemic-euglycemic clamp) was evaluated in 22 African American and 21 Caucasian adolescents on two occasions: 1) infusion of normal saline and 2) infusion of 20% intralipid.


RESULTS
During intralipid 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 African American (normal saline 7.65 +/- 0.61 vs. intralipid 5.15 +/- 0.52 micromol x kg(-1) x min(-1) per pmol/l) and Caucasian subjects (normal saline 8.97 +/- 0.85 vs. intralipid 5.96 +/- 0.56 micromol x kg(-1) x min(-1) per pmol/l) (P < 0.001).


CONCLUSIONS
African American and Caucasian adolescents respond to FFA elevation similarly through increased fasting insulin secretion to maintain fasting glucose homeostasis and reduced peripheral glucose uptake and insulin resistance. Thus, African American adolescents are not more susceptible to FFA-induced insulin resistance than Caucasian youth.
Burns
Stephen F
SF
Division of Weight Management and Wellness, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
Kelsey
Sheryl F
SF
Arslanian
Silva A
SA
D000273:Adipose Tissue / Q000033:anatomy & histology; D000293:Adolescent; D044383:Black People / Q000706:statistics & numerical data*; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D015992:Body Mass Index; D002096:C-Peptide / Q000097:blood* / Q000187:drug effects; D004958:Estradiol / Q000097:blood; D005217:Fat Emulsions, Intravenous / Q000494:pharmacology*; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007328:Insulin / Q000097:blood* / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D013739:Testosterone / Q000097:blood; D014280:Triglycerides / Q000097:blood; D044465:White People / Q000706:statistics & numerical data*; D001741:Black or African American
D001786:Blood Glucose; D002096:C-Peptide; D004958:Estradiol; D005217:Fat Emulsions, Intravenous; D005230:Fatty Acids, Nonesterified; D006442:Glycated Hemoglobin; D007328:Insulin; D013739:Testosterone; D014280:Triglycerides