In this prospective, randomised, open trial, we wanted to evaluate the efficacy and safety of hourly subcutaneous (SC) insulin lispro administration in the treatment of diabetic ketoacidosis (DKA) in comparison with intravenous (IV) regular insulin treatment. Twenty patients were enrolled in the study. The patients were randomly assigned into two groups. Following a bolus injection of 0.15 U/kg IV regular insulin, group L received half of this dose as hourly SC insulin lispro while group R was treated conventionally with IV regular insulin infusion. At the end of treatment period, time that needed for normalisation of serum glucose, beta-hydroxybutyrate, blood pH and urine ketone levels were not different in groups L and R. There was no mortality or serious side effects in both groups. In this study, we revealed that treatment of mild and moderate DKA with SC insulin lispro is equally effective and safe in comparison with IV regular insulin.