In Reply Mr Zitser raises an important question about whether a history of comorbidity should have been adjusted for in our investigation of intrauterine exposure to maternal diabetes during pregnancy and risk of ASD in offspring. We argue that a history of comorbidity should have been adjusted for because the main focus of our study was maternal glucose during pregnancy, with the exposure categorized as preexisting diabetes, gestational diabetes mellitus diagnosed at 26 weeks’ gestation or less or diagnosed at more than 26 weeks’ gestation, or no diabetes. As shown in Table 2 in the article, compared with unexposed children, the crude hazard ratio (HR) for ASD in children whose mothers had preexisting diabetes (HR, 1.59) was almost identical to the crude HR in children whose mothers had gestational diabetes diagnosed at 26 weeks’ gestation or less (HR, 1.63).
Xiang AH. Maternal Diabetes and Autism in Offspring—Reply. JAMA. 2015;314(4):407. doi:10.1001/jama.2015.7256