Inactivating mutations in GCK can be classified into two categories: (1) homozygous inactivating mutations in the Gck gene, which lead to severe conditions like PNDM, and (2) heterozygous inactivating mutations in the Gck gene, which result in a milder form of the condition, such as GCK MODY, typically exhibiting fasting hyperglycemia [72]. This evidence concerns the gene GCK and Hyperglycemia.