Diagnosis of MODY in the offspring of parents with insulin-dependent and non-insulin-dependent diabetes mellitus.

Maturity Onset Diabetes of the Young (MODY) is an autosomal dominant monogenic form of type 2 diabetes mellitus (DM) representing 5% of youth-onset DM in the Caucasian population. In young adults the disease can be present as either non-insulin dependent or insulin-dependent DM. The diagnosis of this genetic disorder in children and adolescents is rare because of the mild glucose metabolism disorder at this time. We performed a metabolic, autoimmune and genetic study in 40 offspring of young parents affected by insulin-dependent DM (Group A) and in 35 offspring of young parents affected by early-onset non-insulin-dependent DM (Group B). Two children of Group A (5%) were found to be affected by fasting hyperglycemia and carry a GCK gene mutation that in one case was present also in the diabetic father. Eighteen offspring of Group B (51%) were positive for GCK or HNF-1alpha gene mutations present in the affected parents. All but two of these young patients had impaired fasting glucose (IFG) or impaired glucose tolerance (IGT). Eleven of them were younger than 16 years. We conclude that screening for DM in youth should be extended to MODY in young families with both non-insulin-dependent and insulin-dependent DM. The sensitivity of the metabolic tests will precede the genetic diagnosis.