Prefilling Insulin Syringes


Can syringes be prefilled for future use of insulin for the next few days? I was told once that syringes cannot be prefilled, but I cannot find information in the literature to support this.


I'll assume that you are not interested in using insulin pens, which contain insulin that was prefilled by the manufacturer. (Note: it's important to first understand how to draw medicine from a vial.)

For some insulin products, pre-filling insulin syringes for use in the next few days has been a standard practice in some settings. However, at least one insulin (Lantus, AKA insulin glargine) becomes cloudy by day 3 and hence the manufacturer "does not recommend prefilling syringes with Lantus and storing for any period longer than needed for application."

Prefilling syringes with insulin has been commonly done in some settings, such as when a home health nurse or aide is visiting a blind person with diabetes every-few-days.

Several thoughts to minimize the possibility of problems:

  • Set an upper limit on the number of days worth of insulin that you pre-fill. There's no science behind the number that I'm aware of, but I'd suggest a week or less.

  • Store the preloaded syringes in the refrigerator, both to preserve the potency of the insulin and to help decrease the very remote chance of bacterial contamination causing bugs to grow in or on the syringes or needles.

  • If you give more than one shot per day, be sure the syringes you have preloaded for the different shots are stored separately. I'd suggest you get multiple clear drinking glasses, label them appropriately (e.g., "MORNING shot" and "EVENING shot"), keep the loaded syringes in the glasses, and keep the glasses in the refrigerator.

  • If you're going to prefill syringes with an insulin product that's a suspension (so-called "cloudy insulin" such as NPH), be sure to periodically remix the insulin that's in the vial as you're loading the syringes so that the doses are all equally concentrated.

  • Replace the cap on the needles. No science behind this that I'm aware of but it sounds like a good idea.

  • Store the capped needle-syringe units in a container with the needle end capped and pointing up. Again, no science behind this that I'm aware of but it sounds like a good idea.

  • Before using a prefilled syringe, allow the syringe to warm up for 5 to 10 minutes. Or warm it by gently rolling the syringe between your hands. Not sure there's any harm in giving cold insulin, but maybe it hurts a bit less if warmed. Also, see next paragraph.

  • If the syringe had been preloaded with an insulin solution ("clear insulin"), make sure the insulin is still clear before injecting. If there is a cloudy appearance that doesn't disappear with warming, or if there are clumps of solid stuff, don't use that pre-filled syringe. Something went wrong, and the solid stuff isn't worth injecting. (Yes, I realize a blind people with diabetes can't do this. But their neighbor or a friend could.)

  • If the syringe had been preloaded with an insulin suspension ("cloudy insulin"), make sure all the insulin is still in suspension before injecting. If there are clumps of solid insulin, don't use that pre-filled syringe as the absorption rate of the chunks of solid insulin from the subcutaneous tissues might be unpredictable if they get through the needle and into you.

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