The prolonged action of daily injections of beef ultralente insulin provides a source for the basal, steady state insulin supply which diabetics need in addition to their meal requirements. The complete distinction between basal and meal insulin requirements, provided by two or three injections of soluble insulin per day, allows simple rules to guide both the physician and patient. Thus, the required ultralente dose needs to be continued daily, irrespective of illness or missing meals, whereas the soluble insulin requirements are given according to meals. When starting ultralente insulin therapy a loading dose is required. The doses of ultralente and soluble insulin needed for different severities of diabetes and degrees of insulin resistance can be predicted. A simple regimen to cover the decreasing insulin requirements of newly presenting, ketotic juvenileonset diabetics has been developed. During surgical operations the continued basal insulin supply, from ultralente insulin, greatly facilitates diabetes control. Whilst many patients have improved nocturnal blood glucose control after transfer to ultralente insulin, optimal control of diabetes sometimes remains dimcult in view of the pre-breakfast plasma glucose rise and the longer action of subcutaneous soluble insulin than the physiological meal insulin response. Purified monocomponent beef ultralente insulin is antigenic, and human ultralente insulin might be advantageous.
DISTINCTION OF MEAL AND BASAL
INSULIN REQUIREMENTSWhen insulin therapy was first instituted, injections of short-acting, soluble insulin were given to cover meals. In the 1930's it became apparent that a background, basal insulin requirement was additionally needed, and this was particularly shown with insulin infusion studies in dogs (6). The first long-acting insulin preparation available was protamine zinc insulin, followed by the crystalline insulin zinc suspensions, e.g. lente, and isophane insulin. Whilst diabetics have often been treated by combinations of short-and medium-or long-acting insulins, specific administration of different insulins to provide completely separate basal and meal insulin requirements have not often been used. During the last 20 years, one of the most common regimes attempting to obtain optimal diabetic control has been twice daily soluble and isophane insulin injections, with the intention that the morning soluble and isophane injections covered breakfast and lunch respectively, and the evening injections covered the evening meal and night respectively (13). However, the evening isophane injection is of medium-action, and does not provide the required constant basal insulin delivery needed during the night (22).