The effect of mixing human soluble and human crystalline zinc-suspension insulin: plasma insulin and blood glucose profiles after subcutaneous injection.

The effect of mixing human soluble insulin with two newly developed formulations of human crystalline zinc-suspension insulin was studied in two groups of 8 normal and 6 diabetic subjects. Mixing Human Actrapid with Human Ultratard and Humulin-S with Humulin-Zn, for 60 s before subcutaneous injection, significantly blunted the rise in free insulin levels (p less than 0.05) and the onset of action of the short-acting insulins (p less than 0.01). The loss of solubility that occurs on mixing these insulins, with the consequent loss of the rapid acting component, may diminish their therapeutic usefulness in the control of post-prandial blood glucose.