In this case report a 40-year-old insulin-treated male patient presented with a KCNJ11 R201H mutation, which can cause neonatal diabetes. After initiation of treatment with high doses of the sulfonylurea glibencamide in combination with the glucagon-like peptide 1 receptor agonist liraglutide, insulin treatment of the patient could be terminated. The first nine months after termination of insulin treatment the glycated haemoglobin concentration was 48-54 mmol/mol (i.e. 6.5-7.1%).