Q: All insulin vials are packaged with an insert that tells you not to use the insulin if the solids stay caked when you roll or shake the vial. For around 23 years, I used Iletin I and never encountered that problem. The solids always distributed themselves through the liquid the way they were supposed to. In two or three years of using Humulin, however, I’ve had to throw away at least four vials because the insulin cakes up and will not uncake itself no matter how much rolling, tipping or shaking I do. I can’t imagine why the old “standard” insulin, which worked better in general, cost less than what we’re using now, and tended to survive better on the shelf, is no longer produced in this country but is apparently still made in eastern Europe, where medicine is supposedly less advanced!
A: As you point out, it is important to resuspend all insulins that come in the form of a suspension, such as Humulin 70/30, NPH, Lente, Ultralente and Humalog Mix 75/25. As the product information indicates, Humulin NPH should look uniformly cloudy or milky after mixing. Do not use it if the insulin substance (the white material) remains visibly separated from the liquid after mixing. Do not use the vial or pen if there are clumps in the insulin after mixing or if solid white particles stick to the walls of the vial or cartridge, giving it a frosted appearance. If you note anything unusual in the appearance of an insulin suspension, or if you notice your insulin requirements changing markedly, you should consult your doctor.
John H. Holcombe, MD
Eli Lilly and Company