In this national cross-sectional analysis of 156 773 children in 2018-2019 commercial and Medicaid claims databases, 27.3% of children diagnosed with obesity at well-child visits received laboratory screening that was adherent to American Academy of Pediatrics guidelines, and 23.0% received potentially unnecessary thyroid or insulin testing. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.