Abstract
Protamin zinc insulin preparations are known to exert an effect more prolonged than that of equal unitage of unmodified (regular) insulin. Recently claims have been offered that the effect of insulin in the form of zinc insulin crystals is similarly prolonged, but in lesser degree. The issue has been confused through the use of clinical observations as the basis for reported conclusions. In view of the many factors which can influence the quantitative response to insulin, the need for standardized conditions of study is apparent. If human subjects are to be used, the constancy of insulin requirement should be established through the use of prolonged control periods wherein daily fluctuations of blood sugar are known.
It has been demonstrated recently 1 that with suitable treatment, the insulin requirement of the diabetic child decreases sharply, once aglycosuria is established, the final daily insulin requirement being 30 to 70% lower than that commonly given under customary methods of treatment. Once such stabilization has been accomplished, the child's insulin requirement is relatively constant and he can be maintained for long periods of time in a state of aglycosuria, with relative freedom from shocks and with blood sugar values which approach those of the normal non-diabetic child. Such a subject is eminently suitable for the study of variations in effectiveness of different insulin preparations. The amount of fluctuation of blood sugar values during the 24 hours can be used as an objective method of comparison.
The diurnal blood sugar fluctuation of 12 diabetic children has been studied when the insulin requirement has been given as regular insulin, protamine zinc insulin, and zinc insulin crystals. The studies have involved a total of 1074 days and 1967 determinations of blood sugar.
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