Racial/ethnic and sex differences in the ability of metabolic syndrome criteria to predict elevations in fasting insulin levels in adolescents

Abstract

Objective: To evaluate racial/ethnic and sex differences in the relationship between metabolic syndrome (MetS) diagnosis and fasting insulin in adolescents.

Study design: We analyzed data from the National Health and Nutrition Evaluation Survey 1999-2008 for 3693 non-Hispanic-white, non-Hispanic-black, and Hispanic adolescents (12 to 19 years of age). We used linear regression to evaluate differences in fasting insulin levels between those with and without an adolescent adaptation of ATPIII-MetS in a sex- and race/ethnicity-specific basis.

Results: Females had higher insulin levels than males, and non-Hispanic blacks and Hispanics had higher levels than non-Hispanic whites. Adolescents with MetS had higher insulin levels than those without MetS. The difference in insulin levels between those with and without MetS was greater in non-Hispanic blacks than in non-Hispanic whites (P < .05) but not Hispanics (P = .10). The sensitivity of MetS in detecting elevated insulin levels was lower in non-Hispanic blacks and females than in other ethnicities and males, respectively. Correlations between insulin and individual MetS components were similar among ethnicities.

Conclusion: MetS diagnosis performed more poorly in predicting elevated insulin levels in non-Hispanic blacks and in females. These data support the hypothesis that non-Hispanic blacks do not meet current criteria for MetS until they have reached a more advanced degree of insulin resistance.

Figure 1

Adjusted geometric means of insulin by sex, ethnicity and MetS status. Estimated geometric means (95% CIs) for A, males and B, females among adolescents with and without MetS, for non-smokers with a high school degree and an income-to-needs ratio = 2. Ratio of adjusted geometic means (and 95% CIs) of fasting insulin (MetS+/MetS−) by ethnicity for C, males and D, females. Comparisons between ethnic groups by corresponding MetS status are : * p<0.05, **p<0.01, both vs. non-Hispanic whites.

Figure 2

Sensitivity of a diagnosis of MetS to detect elevated fasting insulin by sex- and ethnicity. A “high” fasting insulin was defined as the 95^th percentile for non-overweight adolescents (16.0 IU/mL). Comparisons between racial/ethnic groups by corresponding sex and MetS status are : * p<0.05 vs. non-Hispanic whites; # p<0.05 vs. Hispanics. Comparisons between sexs: § p<0.05 females vs. males.