Since several excellent comprehensive reviews have been recently published on both molecular and clinical aspects of monogenic diabetes [5,8,9], this article will almost exclusively concentrate on the clinical strategy that can be specifically pursued in carriers of mutations in actionable genes, including ABCC8, KCNJ11, GCK, HNF1A, HNF4A, HNF1B, PPARG, GATA4 and GATA6 [6] see Table 1. Here, HNF1A is linked to diabetes mellitus.