The Cold Facts on Insulin
Campbell says to look at each new insulin vial carefully and make sure you know its proper appearance; any changes may mean the drug has lost its potency. Insulin comes in two basic forms: solution and suspension, with significantly different appearances.
Solution forms include regular and Novolog (insulin aspart), Humalog (insulin lispro), Lantus (insulin glargine), Apidra (insulin glulisine), Humulin R, Novolin R, or Levemir (insulin detemir), which should remain clear. "Do not use it if it appears cloudy or has any particles," Sulli says.
Suspension forms include mixtures (Humalog Mix 75/25, Humalog Mix 50/50, Humulin N, 70/30, 50/50, and Novolog, Novolog Mix 70/30, Novolin 70/30, Novolin N) and should have an even, cloudy appearance after gentle mixing or rolling.