Objective: Adiponectin is an adipose tissue protein with important insulin-sensitizing, anti-inflammatory, and cardioprotective properties but is paradoxically lower in obese individuals. Sex differences in adiponectin have been reported in adults and adolescents but not in prepubertal children. In this study, we hypothesized that sex differences in adiponectin would develop during puberty and would be influenced by level of adiposity.
Research methods and procedures: Adiponectin levels were measured in 1196 white and African-American adolescents. Insulin resistance was estimated using the homeostasis model (HOMA-IR). Demographic, developmental, and metabolic variables, including interactions with adiposity measurements, were evaluated for independent relationships with adiponectin levels.
Results: Overall, adiponectin levels varied significantly by sex, race, adiposity, and puberty stage. Significant sex differences in adiponectin developed after the onset of puberty, particularly in lean adolescents. Adolescent boys had lower adiponectin levels in post-puberty compared with pre-puberty (p = 0.01) and had lower levels than girls in both puberty and post-puberty (both p < 0.001), after adjusting for race, BMI z-score, and natural logarithm-(HOMA-IR). Sex differences were also conditional on adiposity level, with significant sex differences among lean (p < 0.001) but not among non-lean (p = 0.16) adolescents. Adiponectin levels in girls decreased more with increasing adiposity than in boys (p = 0.004), but only marginally so after standardizing for girls' higher mean adiponectin level (p = 0.11).
Discussion: Sex differences in adiponectin are dependent on both puberty stage and adiposity in adolescents, such that by post-puberty, non-lean boys exhibit the lowest levels of adiponectin.