Maturity-Onset Diabetes of the Young (MODY): Making the Right Diagnosis to Optimize Treatment

Maturity onset diabetes of the young (MODY) is a rare but increasingly recognized cause of diabetes in young people. It is a monogenic disorder that typically presents at <25 years of age, is non-insulin dependent and is familial, with an autosomal dominant pattern of inheritance. The most common forms of MODY are caused by mutations in glucokinase and hepatic nuclear factor 1 alpha or 4 alpha genes and account for almost 80% of cases of MODY. MODY is commonly misdiagnosed as type 1 or type 2 diabetes and, as a result, patients are often inappropriately managed with insulin when they can be more effectively managed with oral sulfonylureas. Therefore, making the right diagnosis is critical for effective treatment as well as for genetic counselling and, more important, for patients' quality of life. In this review, we aim to raise awareness about MODY among diabetes clinicians by describing key clinical and laboratory features of the most common forms of MODY, outlining features that might help to differentiate MODY from type 1 and type 2 diabetes and providing information about clinical tests and tools that might assist in identifying patients who are most likely to benefit from molecular genetic testing.