Absorption kinetics and action profiles of intermediate acting human insulins

The effects of the currently available intermediate acting human insulins on plasma insulin levels and action profiles, assessed by the euglycaemic clamp technique for a period of 8 hr following the administration, were studied in 8 healthy volunteers. The amount of insulin administered was 0.33 IU/kg body wt., using the NPH-insulins Humulin NPH, Insulatard Human, and Protaphane HM and the zinc insulins Monotard-HM and Humulin Zinc. After administration of NPH-insulins an earlier rise of plasma insulin levels was observed, reaching a plateau after about 3 hr, whereas after injection of zinc insulins the plasma insulin levels only gradually increased during at least the first 5-6 hr after administration. Glucose requirements followed a more or less similar pattern, although within the NPH-insulins Protaphane-HM lagged slightly behind during the first 2 hr when compared to Humulin NPH. We conclude therefore, that human NPH-insulins show a faster action profile as compared to human zinc insulins. This difference should be taken into account when switching over from one insulin to another.