Before each use, take a moment to inspect the insulin prior to drawing it into the syringe; clear insulins should appear not discolored and clear; suspended insulins should be uniform in their cloudiness[1].

Do not use the insulin if:

  • Clear insulin that looks discolored or has turned cloudy, contains particles or haze[8].
  • Cloudy insulin that appears yellowish or remains lumpy or clotted after mixing[9][10].

If you made a mistake and forgot to put the insulin back into the refrigerator, even for several hours, there should be no problem. Many keep their insulin (see instructions for your brand) at room temperature all the time[11]. When comparing it to insulin which is in the fridge except when used, it may be more likely to have slight potency loss. If the insulin was exposed to heat or direct light for a while when it was out of the refrigerator, or shaken vigorously or dropped a long way, the best thing to do would be to start with a new vial[12].

Injecting cold from the refrigerator insulin[13] can sting, regardless of what species, type or brand. Bringing the insulin to room temperature by removing it from the fridge before actually using it can help avoid painful injections. Warming the capped insulin syringe with your hands can have the same effect. Some people tuck the capped and filled syringe under their arm for a few minutes to warm it before use.

Do NOT attempt to warm insulin using a stove, microwave, etc.; you may destroy the insulin by doing so[14].

Injection tipsEdit

Do NOT wipe the needle with alcohol as it removes the protective coating which makes injection easier and less painful[15].

Injecting any insulin at the same site repeatedly over time can cause a lipodystrophy: either lipoatrophy[16] or lipohypertrophy. Either makes absorption unreliable.

But varying the injection site can cause variability in action profile, too. This page illustrates[17] illustrates the most common areas humans with diabetes inject insulin and explains how absorption differs in various areas of the human body. This is true for ALL insulins.

The new shot area needn't be very far from where the last shot was given--the distance of the width of 2 fingers will do fine as a measure[18].

Most of us dealing with pet diabetes vary the side we give the injections in--right side mornings and left side evenings, for example. This is another help in avoiding giving shots in the same areas[19].

Many people give insulin shots in the scruff of the pet's neck, which is now considered to be a less than optimum choice. The neck area provides poor insulin Absorption, due to it not having many capillaries, veins. etc. (vascularization).

Other sites suggested by Dr. Greco include the flank and armpit[20].

Intervet recommends giving injections from just back of the shoulder blades to just in front of the hipbone on either side, from 1 to 2 inches from the middle of the back[21].

  • To eliminate bubbles: If drawing insulin from a vial, set the syringe plunger to the dosage you want to draw, put the needle into the top of the vial while the vial is still upright, and push all the air out of the syringe. This will maintain air pressure equilibrium in the vial once you draw the dose and, because the vial is upright, will not cause air bubbles to mix with the solution. Turn the vial upside down and draw the insulin slowly. See note.
  • If you do get air bubbles into the syringe, it's ok with most insulins to re-inject the insulin into the vial and draw again until the air is gone[22]. Check that this is ok with your insulin. See also injecting insulin. Slower draw is less likely to draw bubbles.
  • Another way to get rid of syringe air bubbles is to hold the syringe upright and give it a tap or two with your finger. The problem with having air bubbles in the injection is that you will not be getting the full dose of insulin; the bubbles take the place of it[23].
  • Some people prefer to gently jiggle their vials to make any air bubbles rise to the top, away from where the needle will draw[24].

Note: The Feline Diabetes Message Board's Lantus group does not recommend regularly injecting air into a vial of Lantus (insulin glargine) as this may affect its longevity.

Injection problemsEdit

There are sometimes leakage problems, when some insulin is lost when the needle is removed from the skin[25]. Some possible reasons and "fixes" for this are holding the "pinch" or "squeeze" too long which you made to give the shot.

The skin, now with insulin under it, is still being "squeezed" as it was before the insulin went under the skin. The "pinch" forces some of the insulin back out from the newly-created hole in the skin.

Releasing the "squeeze" or "pinch" first, then counting to 10 before removing the needle from the skin may give the insulin time to penetrate the fat layer and prevent leakage. Short needles can also cause insulin leakage--switching to longer ones can also help.

More information can be found on the following pages: injecting insulin, diluting insulin, fine_doses, mixing insulin, Insulin, Syringe, Insulin pen.


  1. Therapy-Stability & Storage
  2. Flocculation & Loss of Potency of Human NPH Insulin-Diabetes /Care-ADA-1988
  3. Flocculation of NPH Insulin-Revista Clinica Espanola-(English Translation)-1994
  4. Frosting Caused in NPH/Isophane Insulin By Heat/
  5. Dorlands Medical Dictionary-Definition of Flocculation
  6. Frosting Caused in NPH/Isophane Insulin By Heat/
  7. ADA-Diabetes Forecast, 2006-Storage & Safety-Frosting of NPH, Lente, Ultralente Insulins-Page 5
  8. & Heat
  9. Injection Insulin-Transcript of American Diabetes Association Videotape-2003
  10. ADA-Diabetes Forecast, 2006-Storage & Safety-Particles or Clumps in NPH, Lente, Ultralente Insulins-Page 5
  11. With Insulin
  12. Tips on Caring for Diabetic
  13. Injecting Cold Insulin
  14. the D Team-2005
  15. for Comfortable Injections
  16. Lipoatrophy can Happen With Any Subcutaneous Insulin-Endocrine Abstracts-2006
  17. Common Human Insulin Injection Areas & Their Absorption Rates
  18. Joslyn Diabetes Center-Tips for Injecting Insulin
  19. BD Diabetes-FAQ's About Diabetic Dogs-Dr. Greco
  20. Better Medicine E-Newsletter-June 2006
  21. Vetsulin-Preparing Insulin & Giving Injection-Page 2
  22. Injecting Insulin-Transcript of American Diabetes Association Videotape-2003
  23. American Diabetes Association 2002 Position Statement-Insulin Administration
  24. Diabetes Self-Management-Injecting Insulin 101
  25. Insulin Leaking From Injection Site
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