A dominantly inherited form of type II diabetes that occurs in young people (less than 25 years old) and is not insulin-dependent. MODY type 3 is due to a mutation of the hepatic transcriptor factor-1 gene on chromosome 12q24.2. The hyperglycemia in this form of the condition tends to increase with time and hence eventually requires treatment in the form of medication in many patients. See also MODY syndrome, type III