Even in T2D, where gene mutations are related to glucose homeostasis in β cells and insulin target tissues (45), genetic variants affecting viral response pathways have been identified; for example, a TYK2 promoter variant associated with a deteriorated cytokine response has been identified as risk factor for T1D as well as T2D (46) and correlates with increased T2D severity (47). This evidence concerns the gene TYK2 and type 2 diabetes mellitus.