Short answer: Insulin labels give two kinds of checks: how it looks and how it has been kept. Clear insulins such as Lantus and Humalog should be clear and colorless, and the labels say not to use them if cloudy, colored or showing particles. Humulin N should look white and cloudy after mixing, and its label says not to use it if it looks clear or has lumps. Labels also say to throw out insulin that has frozen or passed its day limit.
Most insulins are clear solutions. The Lantus label (section 2.1) says to check vials and pens for particles and discoloration before each dose and to use Lantus "only if the solution is clear and colorless with no visible particles." Its patient leaflet adds that if Lantus is cloudy or slightly colored, it should go back to the pharmacy for a replacement.
The Humalog label says the same in its own words: Humalog "should appear clear and colorless," and it should not be used if particles or coloration are seen. The vial instructions add thick, cloudy or colored insulin, or lumps or particles, to the list of reasons not to use it.
Humulin N is NPH insulin, a suspension rather than a solution, so it is meant to look cloudy. Its label (section 2.1) says it should "appear uniformly cloudy after mixing" and must not be used if particles are seen.
The instructions ask for the vial to be rolled between the palms at least 10 times and turned upside down at least 10 times, and the KwikPen rolled 10 times and turned 10 times. "Mixing is important to make sure you get the right dose." After mixing, the instructions say not to use it if it looks clear or has any lumps or particles in it.
| Insulin | Should look | Do not use if |
|---|---|---|
| Lantus (glargine) | Clear and colorless | Cloudy, colored or has particles |
| Humalog (lispro) | Clear and colorless | Thick, cloudy, colored, or has lumps or particles |
| Humulin N (NPH) | White and evenly cloudy after mixing | Looks clear after mixing, or has lumps or particles |
Insulin can look normal and still be past its limit. Each label sets how long it can be used once opened or kept at room temperature (up to 86°F, 30°C):
| Product | Opened or at room temperature | Where to keep it once opened |
|---|---|---|
| Lantus vial | 28 days | Fridge or room temperature |
| Lantus SoloStar pen | 28 days | Room temperature only |
| Humalog vials and pens | 28 days in total at room temperature | Vials: fridge or room temperature; pens: room temperature only |
| Humulin N vial | 31 days in total at room temperature | Fridge or room temperature |
| Humulin N KwikPen | 14 days in total at room temperature | Room temperature only |
All three labels say not to freeze insulin and not to use it if it has been frozen, and to protect it from heat and light. The Lantus leaflet says a vial that has been frozen or overheated should be thrown away. Unopened insulin kept in the fridge is good until the expiration date on the label.
The labels do not give a home test for insulin strength. One clue they do name: in its pump section, the Humalog label lists "degraded insulin" next to pump problems as a cause of quickly rising blood sugar and ketones. Unexpected highs are worth raising with the prescriber or pharmacist, along with how the insulin was stored.
Day limits are easy to lose track of with several pens or vials in use. Dose Track keeps each vial or pen in your inventory with its dates, so the day count is there when you need it. Storage details for each product are on the Lantus, Humalog and Humulin N storage pages.
Read more on Dose Track: How to store Lantus · How to store Humulin N · Left out of the fridge · Vials and inventory in Dose Track