One disease that is particularly troublesome to identify is maturity‐onset diabetes of the young (MODY), which is a monogenic diabetic disease whose most prevalent types are glucokinase (GCK)‐MODY, hepatocyte nuclear factor 1‐α (HNF1A)‐MODY, and hepatocyte nuclear factor 4‐α MODY. This evidence concerns the gene GCK and MODY.