Does anyone have a reliable method of preparation or administration of diluted insulin? What is your experience in identifying an error in preparation or administration? What are the most frequent errors identified?

I give patients written instructions on how to mix insulin in a sterile vial. I also make sure to pick amounts that are easy to mix with existing syringes. Anyone who can mix insulin correctly in a syringe can make a diluted preparation accurately in a sterile mixing vial.

The most important thing is to clearly label the insulin bottle with exactly how it was made (for instance do you mix 0.3 cc of insulin and 2.7 cc of diluent to make a 1/10 strength insulin, or did you mix 1 cc if insulin and 9 cc of diluent?) Mark the bottle with the “strength” (for example, 1/10 strength) above and mark on the bottle what one “line” on an insulin syringe equals (For instance one “line” above equals 1/10th unit above).

Then, I tell my patients we will communicate in terms of actual “lines” drawn up on the insulin syringe, not units and they should just remind me what strength insulin they are using. You can do this with a pump too, but have to be clear you are telling them what numbers to program, and what they program is not really equal to the “real units”.

I usually find the patients are more consistent in mixing insulin than the pharmacists. Unfortunately, the insulin companies will not ship the diluent and mixing vials directly to the patients, only to doctors and pharmacists.

TGL
Additional comments from Dr. Larry Deeb:

I have patients who dilute Humalog using the diluent provided by Lilly. They usually mix 1:1 in the mixing bottle provided which seems to work. If you can use a pump successfully, you ought to be able to mix. That means it isn’t for everyone.

LD