Relative to Caucasians (C), African-American (AA) children and adults have lower indices of insulin sensitivity (S(i)) and a higher acute insulin response to glucose (AIR(g)). Among AA children, AIR(g) is greater than that which would be predicted based on lower S(i). The objectives of the present study were 1) to determine whether insulin secretory parameters differ in AA vs. C children and adolescents using C-peptide modeling, 2) to determine whether hepatic insulin extraction differs with ethnicity/race using the C-peptide to insulin molar ratio, and 3) to determine whether the relatively greater AIR(g) among African-Americans is due to greater insulin secretion or lesser clearance. Subjects (n = 76) were AA and C children (mean age, approximately 11 yr). A 3-h tolbutamide-modified iv glucose tolerance test and minimal modeling were used to determine S(i) and AIR(g). First phase C-peptide/insulin secretion and basal, first, and second phase beta-cell sensitivity to glucose were determined using C-peptide modeling with standard kinetic parameters developed in adults. The incremental C-peptide to insulin molar ratio over the 3-h test period, an index of hepatic insulin extraction, was calculated with the trapezoidal method. S(i) was lower and AIR(g) was higher in AA vs. C children. First phase C-peptide/insulin secretion and first phase beta-cell sensitivity to glucose were approximately 2-fold greater in AA vs. C children (P < 0.001); there were no between-group differences in basal or second phase beta-cell sensitivity to glucose. Hepatic insulin extraction was lower in AA vs. C (3.77 +/- 1.78% vs. 5.99 +/- 2.18%; P < 0.001). Multiple linear regression modeling indicated that first phase C-peptide/insulin secretion and hepatic insulin extraction contributed independently to AIR(g); however, it was only first phase C-peptide/insulin secretion that explained the significant independent contribution of ethnicity/race to AIR(g) after adjusting for S(i). The results of this study suggest that greater AIR(g) among AA is due to both greater insulin secretion and lesser hepatic insulin extraction, and that AIR(g) above that predicted based on lower S(i) is due to greater insulin secretion. The insulin secretion data await verification that the kinetic parameters used apply to children and AA.
In pubertal children, sexual maturation, BMI, dietary intervention (in girls), and dietary cholesterol (in boys) were significant in determining LDL-C. Sexual maturation was the factor associated with the greatest difference in LDL-C. Clinicians screening for dyslipidemia or following dyslipidemic children should be aware of the powerful effects of pubertal change on measurements of lipoproteins.
Objective
To evaluate the contribution of European genetic admixture (EUADM) to the insulin resistance syndrome (IRS) in a multi-ethnic sample of children aged 7–12 years and if body fat affects this relationship.
Study design
Anthropometric measurements and blood pressure were assessed in 243 children. After an overnight fast, an intravenous glucose tolerance test was conducted, and measures of fasting insulin/glucose, lipids, insulin sensitivity (SI), and acute insulin response to glucose (AIRg) were obtained. The proportion of EUADM was determined by maximum likelihood estimation using 140 ancestry informative markers. Participants were stratified into tertiles according to the proportion of EUADM for analyses. Subjects were categorized as lean or obese using percent fat cut-points (25% in boys, 30% in girls).
Results
Among lean subjects (72%), the tertile representing the greatest proportion of EUADM was associated with higher SI (p<0.001) and glucose (p<0.05) and lower insulin (p<0.05), AIRg (p<0.001), HDL-C (p=0.05), and blood pressure (p<0.05). However, among obese subjects, EUADM was associated with only SI (p<0.05).
Conclusion
Our results suggest that population differences in the IRS likely have a genetic component. However, the influences of genetic background may be masked by obesity.
Objective: We assessed the racial (Black-White) differences in glycemic control, prevalence of abnormal lipid profi les and factors infl uencing temporal trends in children with type 1 diabetes (T1DM).Methods: This retrospective study was done in children with T1DM. The outcome measure was based on glycemic control and all lipid determinations which were stratifi ed according to the published guidelines.
Results:The study included 181 children; 76.2% Whites and 23.8% Blacks. The mean glycated hemoglobin (A1C) was higher in Blacks than in Whites (p Ͻ 0.0001). Blacks had elevated total cholesterol (TC) (p = 0.0013), lower TC/HDL ratio (p Ͻ 0.0001) and higher concentration of HDL (Ͻ0.0001) when compared to Whites. The longitudinal analyses over a 5 year period showed changes in A1C signifi cantly associated with changes in the lipid profi les. The lipid profi les in Blacks were more altered by the trend in A1C with changes in the TC (p = 0.0079), non-HDL (p Ͻ 0.0001) and HDL (p Ͻ 0.0001).Conclusions: Black children with T1DM have poorer glycemic control. However they retained excellent levels of HDL when compared to Whites.
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