Islets of Hope  care tips for persons with diabetes

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Article disclaimer

Compiled by Lahle Wolfe, who is not a medical doctor but has diabetes, and is a parent of a young child with diabetes who uses an insulin pump.

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type 2 diabetic woman  M. Sarah Rosenthal
The Type 2 Diabetic Woman

Prefilling Syrgines with Mixed Insulin

Courtesy of:
The Nursing Center Library

An issue important to home health relates to prefilling syringes with glargine insulin. The recommendation is... Don’t Do It.

“How Long Should Insulin Be Used Once a Vial Is Started?” (Sept. 2003 issue of Diabetes Care ) provides an excellent overview of the topic. Concerns about prefilling syringes with glargine are based on a study prefilling syringes from three different manufactures. By day three the Lantus insulin in all syringes visually appeared turbid because of its acid and, additionally, a pH a reaction with the plastic syringe occurs. Prefilling guidelines relative to other insulins:

Aventis... “does not recommend prefilling syringes with Lantus and storing for any period longer than needed for application.”

“BD does not recommend any of their syringes be prefilled more than a few minutes in advance of injection.”

Quote Source
Diabetes Care Journals
(pdf version)

Prefilling Syringes with Mixed Insulin - Another Opinion

Most doctors recommend that when mix insulin you should use it immediately.

However, I did find at least one medical site that suggested a safe way to prefill and use mixed insulin (specifically, Regular and NPH) was by allowing it to "rest" for 24 hours prior to using it.  (The article was written as a guideline for nurses administering insulin to patients.)

Visit: to view the article.  Please, do discuss this with your doctor.


diabetes care tips                                                
Tips for Insulin
Chart for Insulin Storage and Expiration
Article by Lahle Wolfe, Islets of Hope, 02/24/2006

Mini Site Index
Storage (shelf life) of Insulin Pen Cartridges
Storage (shelf life) of Insulin From (bottles) Vials
(room temp, refrigerated & when prefilling syringes and pumps)

Also, see the article on "Tips for Insulin:  Storage"

How long does insulin stay "good" in insulin pen cartridges and prefilled pens?

The shelf-life and viability of insulin in varies according to type of insulin, the type of container it comes in (vial or cartridge) and how it is used (refillable cartridge, syringe, or insulin pump) and manufacturers instructions.  Be sure to read the label information that comes with your insulin pen and insulin.


Storage (shelf life) of Insulin Pen Cartridges


1.5 mL Insulin Cartridges

3 ml Insulin Cartridges

Prefilled Insulin Pens

Humalog 28 days N/A 28 days
Novolin R 30 days 28 days 28 days
Novolin N 7 days 14 days 14 days
Novolin 70/30 mix 7 days  10 days 10 days
Novolog N/A 28 days 14 days

Chart Note:

Always refer to your insulin manufacturer's instructions for care and safety guidelines for using and storing your insulin.


Storage (shelf life) of Insulin From (bottles) Vials

Refrigerated (unopened)

Refrigerated (opened, latex seal punctured)

Stored at Room Temperature (not refrigerated)

Once Drawn into Syringe(1)

Filled Insulin Pump Cartridge

When properly refrigerated (do not freeze) insulin will keep until expiration date on package.

If ever frozen, discard the insulin.

Insulin expiration dates are usually 1-2 years form date of purchase.

Insulin costs about $80/1,000 units (US) and $20-35/1,000 units in Canada.

Once insulin has been opened and the seal has been punctured, use or discard insulin within 28 days.  

Note:  The more punctures you make into the latex seal the faster insulin can degrade.

Insulin that is stored at room temperature should be used or discarded within 28 days.  

Note:  The more punctures you make into the latex seal the faster insulin can degrade.

Insulin drawn into a syringe(1), that is not mixed with other insulin, can be stored in the refrigerator for up to 30 days.

Insulin that is mixed with another insulin (both drawn into a syringe) should be used immediately. (see sidebar)

Do NOT prefill Lantus (glargine) insulin (see sidebar).

Store with needle site UP to help prevent crystalliza- tion in the tip.

Humalog(2) seems to be a little finicky in pumps and you may need to change your cartridge more often (every 27 hours.

Other insulins may a little less sensitive to being in a pump and you may be able to use insulin 3-5 days in your pump.

If you start having hyperglycemia, always change your insulin and canula site.

Chart Notes:

(1) Prefilling Syringes with Insulin

  • BD does NOT recommending prefilling any of their syringes with any type of insulin (see sidebar).
  • If you prefill syringes, be sure to store the syringes with the needle pointing up.  This helps to prevent insulin from crystallizing in the tip.  Separate different doses or types (storing in separate, clearly-marked containers) to reduce the chance of injecting the wrong insulin dose.
  • You still need to check the insulin in the syringe before injecting to make sure its appearance has not changed, and you should warm it by gently rolling between your palms (or let it sit for 5-10 minutes before injecting).

(2) Diabetes Mall:  Humalog and Heat and User Reports

Important notes about storing and using insulin

You should only use about 90% of the insulin in a bottle.  Once you are down to about 10% left, discard it and open a new bottle.

Always refer to your insulin manufacturer's instructions for care and safety guidelines for using and storing your insulin.

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Page Updated 02/25/2006