INTRODUCTION: Hyperglycemia in preterm infants is usually treated with adjustment of glucose intake and, if persistent, with continuous insulin infusion. However, hypoglycemia is a well-known complication of intravenous (iv) insulin treatment. The aim of this study was to evaluate the feasibility of continuous subcutaneous insulin infusion (CSII) in extremely preterm infants. METHODS: Clinical data from extremely premature infants (<28 weeks of gestation) undergoing CSII treatment for severe hyperglycemia in the neonatal intensive care unit were included. Blood glucose levels during CSII, as well as the nutritional intake and insulin intake were recorded. Data were analyzed and compared to a control group of very preterm infants receiving iv insulin therapy. RESULTS: Normoglycemia rates were best in the iv insulin-cohort (n=22, 50.3%) compared to the CSII group (n=15, 15.6%). Hypoglycemia was very rare in both groups (0.4% vs. 0.0%). CSII therapy appears to require higher insulin doses compared to continuous iv therapy to achieve a similar effect. Subcutaneous Insulin therapy in extremely preterm infants is feasible, at least for prevention of hypoglycemia. However, dose control needs to be improved. DISCUSSION AND CONCLUSION: The results justify further model validation and clinical trial research to explore a model-based protocol and the use of CSII in this population.