Stability and reproducibility of the biologic activity of premixed short-acting and intermediate-acting insulins

Mixtures of short-acting and intermediate-acting insulins often represent an effective regimen to achieve near-normal blood glucose values, yet controversy exists concerning the stability and predictability of such mixtures. In a study of diabetic patients, the biologic activity of a specific intermediate-acting insulin (insulatard) and a short-acting insulin (Velosulin) premixed in a 70:30 ratio was reproducible at three intervals and was stable for a period of up to three months. The serum levels of free insulin and the rate of onset and extent of the blood glucose lowering effects were not altered, showed two distinct peaks, and were comparable to those experienced with separate injections of equivalent doses of the intermediate-acting and short-acting insulins.