Leprechaunism is a rare autosomal recessive disease that is characterized by 
severe insulin resistance. This disease is caused by a defective insulin 
receptor and features abnormal glucose metabolism and retarded intrauterine and 
postnatal growth. However, there are few reports on the long-term course of 
leprechaunism. We reported the long-term clinical course and rh-IGF-1 treatment 
in a patient with leprechaunism. During follow-up her diabetes gradually 
deteriorated despite of treatment of rh-IGF-1. Furthermore, she developed 
endometrioid adenocarcinoma at the age of 24 yr. The development of endometrial 
disease must be carefully followed up in this disease.