Introduction:The need of genetic testing and individualized treatment for diabetic individuals with a family history of the condition is discussed in this case study. It emphasizes the significance of early detection and therapy of maturity-onset diabetes of the young (MODY) and the potential advantages of identifying unique mutations that may contribute to the development of diabetes. Case Presentation:A Saudi Arabian woman of 50 years old with a strong family history of diabetes was discovered to have a new mutation in the APPL1 gene related with MODY 14. Prior to age 30, the patient had a history of elevated blood sugar, but had never used diabetes medication. Gliclazide and metformin were prescribed to the patient, resulting in a decrease in HbA1c levels. Conclusion:This case study illustrates the significance of genetic testing in finding novel mutations that may contribute to the development of diabetes and in adapting treatment to the specific needs of individual patients. Detection and treatment of MODY at an early stage helps reduce complications associated with poorly managed diabetes. To completely comprehend the functional repercussions of the APPL1 gene mutation and its impact on the patients long-term health, additional research is required.