BACKGROUND: A 17-year-old female was referred for the reassessment of her type 1 
diabetes mellitus, with which she had been diagnosed at the age of 15 weeks 
owing to symptoms of ketoacidosis. The patient had mild learning difficulties, 
which resulted in her requiring additional support at school. There was no 
family history of diabetes.
INVESTIGATIONS: Measurements of plasma C-peptide and glutamate decarboxylase 
autoantibodies. Molecular genetic testing was performed.
DIAGNOSIS: Intermediate developmental delay, epilepsy and neonatal diabetes 
mellitus (DEND) syndrome as a result of a 59V>M Kir6.2 mutation.
MANAGEMENT: Treatment with high-dose oral glibenclamide replaced insulin 
treatment. Good glycemic control was achieved with levels of HbA(1c) 
consistently below 6.5% and no hypoglycemia.