Body Composition and Markers of Cardiometabolic Health in Transgender Youth Compared With Cisgender Youth

Context: As many as 1.8% of adolescents identify as transgender and many more seek care, yet the impact of gender-affirming hormone therapy (GAHT) on cardiometabolic health is unknown. Objective: To determine insulin sensitivity and body composition among transgender females (TF) and males (TM) on estradiol or testosterone, compared with cisgender females (CF) and males (CM). Design: Pilot, cross-sectional study conducted from 2016-2018. Setting: Academic regional transgender referral center. Participants: Transgender adolescents on either testosterone or estradiol for at least 3 months were recruited. Nineteen TM were matched to 19 CM and 42 CF on pubertal stage and body mass index (BMI). Eleven TF were matched to 23 CF and 13 TF to 24 CM on age and BMI. Main Outcome Measures: 1/[fasting insulin] and body composition (dual-energy x-ray absorptiometry). Results: Total body fat was lower in TM than CF mean +/- SD: (29% +/- 7% vs 33% +/- 7%; P = 0.002) and higher than in CM (28% +/- 7% vs 24% +/- 9%; P = 0.047). TM had higher lean mass than CF (68% +/- 7% vs 64% +/- 7%, P = 0.002) and lower than CM (69% +/- 7% vs 73% +/- 8%; P = 0.029). Insulin sensitivity was not different between the groups. TF had lower body fat than CF (31% +/- 7% vs 35% +/- 8%; P = 0.033) and higher than CM (28% +/- 6% vs 20% +/- 10%; P = 0.001). TF had higher lean mass than CF (66% +/- 6% vs 62% +/- 7%; P = 0.032) and lower than CM (69% +/- 5% vs 77% +/- 9%; P = 0.001). TF were more insulin resistant than CM (0.078 +/- 0.025 vs 0.142 +/- 0.064 mL/mu U; P = 0.011). Conclusions: Transgender adolescents on GAHT have significant differences in body composition compared with cisgender controls, with a body composition intermediate between BMI-matched CMs and CFs. These changes in body composition may have consequences for the cardiometabolic health of transgender adolescents.