Serum Cotinine and Hemoglobin A1c Among a National Sample of Adolescents Without Known Diabetes.

INTRODUCTION: National data suggest tobacco smoke is positively associated with higher glycated hemoglobin (HbA1c) among adults. Our objective was to examine the association between serum cotinine and HbA1c among adolescents without known diabetes. METHODS: We assessed adolescents 12-19 years old (N = 11550) who participated in the 1999-2012 National Health and Nutrition Examination Survey. We applied sampling weights while performing multiple linear regression analyses. RESULTS: The prevalence of serum cotinine indicative of no tobacco smoke exposure (TSE, <0.05 ng/mL) was 43.2%, passive TSE (0.05-2.99 ng/mL) was 38.9%, and active TSE (>3 ng/mL) was 17.9% in our sample. Mean (± standard error) HbA1c in participants with no TSE was 5.16% (±0.01), passive TSE was 5.16% (±0.01), and active TSE was 5.14% (±0.01). No differences in HbA1c were found between TSE groups including sex, age, race/ethnicity, education, income, and physical activity or the fully adjusted model with waist circumference. We found cotinine × sex (p = .01) and cotinine × age (p = .02) interactions. There was an association between cotinine and HbA1c for males but not females. Within males, participants with cotinine ≥3 ng/mL (5.26 ± 0.02) had higher mean HbA1c than those with cotinine 0.05-2.99 ng/mL and <0.05 ng/mL (both 5.20 ± 0.01, p ≤ .02). The negative association between age and HbA1c was stronger for participants with cotinine ≥3 ng/mL than participants with cotinine <0.05 ng/mL. CONCLUSION: No linear association was found between HbA1c and serum cotinine in adolescents overall after adjusting for potential confounders. Differences between TSE groups were found in males. Future research in adolescents should examine chronic TSE over time to examine the potential for development of type 2 diabetes. IMPLICATIONS: TSE has been associated with increased risk for the development of type 2 diabetes among adults. It is unclear if this relationship holds in adolescents. We examined the association between serum cotinine and HbA1c in adolescents without known diabetes who completed the 1999-2012 National Health and Nutrition Examination Survey. Although no association was found between serum cotinine and HbA1c overall while controlling for potential confounding factors, we observed interaction effects that are indicative of TSE influencing HbA1c differentially by sex and age. Reducing TSE in adolescents should be a priority for future tobacco control efforts.