The main difference between "conventional" and "functional" insulin replacement is that the former requires meals to be taken at set times throughout the day to avoid hypoglycaemic insulin reactions, while the latter separates insulin replacement in the basal ("fasting") state from that required with food intake. Such strategy reverses conventional insulin treatment (namely balancing the action of administered insulin by a fixed dietary intake), by substitution with a functional control of hyperglycaemia on the basis of tailored insulin doses. To this end blood glucose self control and systemic blood glucose correction are a must during functional insulin substitution, but not necessarily so during conventional insulin therapy. From this it is apparent that "conventional" and "functional" insulin therapy refer to different strategies, both of which may be intensified by more strict rules, although the term "intensified" remains without any conceptional meaning per se. However, whatever the therapeutic recommendation, the attending physician has to be aware that he must appropriately inform and train the insulin-deficient patient (a) on how to deal with a proposed treatment schedule, and (b) to the point that he fully understands the available therapeutic possibilities and the difference in their quality. Experience has shown that a majority of informed patients opt for functional therapy.