TYK2 and diabetes mellitus: To assess the role of TYK2 under these highly diabetogenic conditions, we analyzed the incidence of diabetes and found that it was slightly reduced in Tyk2−/− NY8.3 NOD mice (60%) compared with Tyk2-sufficient NY8.3 NOD mice (Tyk2+/+, 87.5%; Tyk2+/−, 85.7%) (Supplementary Fig. 4d).