OBJECTIVE: Intrauterine exposure to high maternal glucose is associated with excess weight gain during childhood, but it is not clear whether the excess weight represents increased fat or lean mass. The purpose of this study was to examine the relationship between maternal glucose concentrations during pregnancy and offspring body composition. A secondary goal was to examine whether the association between maternal glucose and children's body fat was independent of energy intake, energy expenditure, or physical activity. RESEARCH DESIGN AND METHODS: Children aged 5-10 years and their biological mothers (n = 27) were recruited. Maternal glucose concentration 1 h after a 50-g oral glucose load, used to screen for gestational diabetes mellitus at 24-28 weeks gestation, was retrieved from medical records. Children underwent dual-energy X-ray absorptiometry to measure body composition, indirect calorimetry to measure resting energy expenditure (REE), accelerometry to measure physical activity, and three 24-h diet recalls to measure energy intake. RESULTS: Maternal glucose concentration during pregnancy was positively associated with children's lean mass (P < 0.05) and adiposity (fat mass adjusted for lean mass; P < 0.05). The association between maternal glucose and children's adiposity was independent of children's REE, percent of time spent physically active, and energy intake (P < 0.001). CONCLUSIONS: Intrauterine exposure to relatively high maternal glucose is associated with greater lean mass and adiposity among prepubertal offspring. Further research is needed to examine the mechanisms by which maternal glucose concentrations during pregnancy influence children's body composition.