Maturity onset diabetes of the young (MODY), the most common monogenic form of diabetes, accounts for 1-2% of all diabetes diagnoses. It is characterized by early-onset diabetes in adolescence or young adulthood (<35 years), and is due to a primary defect in the β-cell function. There are currently 17 genes that are associated with MODY which are included in the AJCH MODY Panel: ABCC8, APPL1, BLK, CEL, GCK, GLUD1, HADH, HNF1A, HNF1B, HNF4A, INS, KCNJ11, KLF11, NEUROD1, PAX4, PDX1, RFX6. These genes account for the majority of MODY cases. GCK and HNF1A account for the majority of cases with HNF1A responsible for 30-65% of cases and GCK responsible for 30-60%of positive molecular cases, with the remaining genes accounting for the rest of the molecular diagnoses of MODY. The phenotype and treatment of MODY is variable depending on the molecular basis/subtype of the condition, therefore genetic testing can facilitate an accurate diagnosis and appropriate clinical management.