This case report describes diagnosis of the uncommon maturity onset diabetes of the young (neurogenic differentiation factor 1-maturity-onset diabetes of the young) after transient autoimmunity during coronavirus disease 2019 infection.<h4>Case presentation</h4>A 19-year-old Mexican male with autism spectrum disorder was diagnosed with diabetes without ketoacidosis during metabolic screening laboratory testing. This evidence concerns the gene NEUROD1 and autism spectrum disorder.