[A monogenetic disorder instead of type 1 diabetes].

Transient Neonatal Diabetes Mellitus (TNDM) is a rare monogenetic disorder characterized by impaired insulin secretion occurring in the first weeks after birth. TNDM goes into remission after a few weeks to months. However, a large number of children develop non-insulin-dependent DM during puberty.In this article we describe a woman who had been treated with insulin since early adulthood because of suspected type 1 diabetes (T1D). During the diagnostic process it became clear that she had been diagnosed with TNDM before. Additional genetic testing confirmed the diagnosis of 6q24-related TNDM. She successfully changed from insulin to oral (tolbutamide) treatment.It is important to pay attention to personal and family history in patients with suspected DM1. Diagnosing monogenic diabetes often has clinical consequences for the index patient as well as family members.