Mixing insulins in 1990.

Lente insulins can be mixed in any ratio at any time. Regular plus NPH insulins seem to be the preferred mixture of rapid- and intermediate-acting insulins because the effect of the combined insulins is the same as that of regular and NPH insulin injected separately. Mixing regular with lente insulins is more complex and needs further study. However, at the present time, if regular and lente insulins are going to be mixed, they should be either mixed and injected immediately, or they should be left to interact for up to 24 hours, in which case the resultant mixture does not have as rapid an action as the immediately injected mixture. Combinations of regular and protamine zinc insulins are rare and complicated by the fact that the resultant product is based upon the ratios of regular to PZI. Generally speaking, protamine zinc insulin is rarely used in humans. It is used by some veterinarians, especially to treat cats with diabetes. The Table summarizes information concerning the mixing of various insulins.