AbstractThis study was undertaken in 10 newly diagnosed diabetic children to assess the usefulness of the practical closed‐loop system in determining insulin doses in conventional treatment. During application of this system of continuous intravenous insulin infusion, the infusion dose was changed according to the hourly monitored blood glucose values. Conventional insulin treatment was started, based on the daily insulin profile obtained by the practical close‐loop system. This consisted of two daily injections of a mixture of short‐ and intermediate‐acting insulins. There was no significant difference in mean blood glucose, M‐value or mean amplitude of glycemic excursions between the two treatments.Compared with the previous insulin regimen in which conventional insulin treatment was performed following the initial treatment for diabetic ketoacidosis without this practical closed‐loop system, good glycemic control was obtained in a shorter period by using this system.Thus, the practical closed‐loop system could be helpful in predicting the starting insulin dose for conventional insu