Insulin Administration And Proper Usage

Insulin is available in concentrations of 40, 100, and 500 units/ml. There are corresponding syringes to use for the measurement of the three concentrations of insulin. If using insulin with 40U/ml, you must measure and administer it with a U-40 syringe; using a U-100 or U-500 syringe would result in the wrong amount of insulin being given, with perhaps a fatal outcome. There may be several types of U-40 syringes available, manufactured to deliver low or high doses. The measurements marked off on those syringes designed for giving a low dose are often easier to read. Your veterinarian (or pharmacist) will tell you what syringes you will be using with the concentration of insulin your pet is receiving.

How is insulin stored and handled?

Insulin comes in a glass vial with a rubber stopper, and must be stored in the refrigerator. Do not use the insulin beyond its expiration date.

How is a dose of insulin measured?

The concentration of insulin is measured in units. Insulin syringes are marked in units, and may also be marked in milliliters. Be sure to use the unit scale. Also, be sure you are using the appropriate insulin syringe for the concentration of insulin you are using.

An insulin syringe has 4 basic parts: the barrel, plunger, needle, and needle guard. Many brands of syringes have the needle permanently attached to the syringe barrel so it cannot be removed.

1. Prior to removing a dose of insulin from the vial, mix and warm the contents by gently rolling the vial between the palms of your hands. DO NOT SHAKE INSULIN as that will cause air bubbles to form, and it will become more difficult to get an accurate measurement. The insulin should be uniformly cloudy in the bottle when you draw it into the syringe. NOTE: We have used a pink solution instead of insulin to better illustrate the steps.

2. Hold the vial stopper-side-down, remove the needle guard from the insulin syringe, and insert the needle of the syringe into the vial through the rubber stopper.

3. Pull back on the plunger of the syringe to draw the insulin into the syringe once, then inject it back into the bottle. Redraw the proper dose back into the syringe. This is helpful in accurately dosing as insulin may stick to the inside of the plastic syringe or an air bubble may be present in the syringe. If any air enters the syringe, you can also expel that back into the vial by keeping the vial upside down, and the needle of the syringe pointing up.

4. Recheck that you have withdrawn the proper amount of insulin

5. Remove the syringe from the vial and replace the needle guard.

6. Return the insulin to the refrigerator

7. You are now ready to administer the insulin

How is an insulin injection given?

To acquaint yourself with what giving an insulin injection may feel like, it is often recommended to practice by injecting water from an insulin syringe into an orange.

To be sure your cat gets her insulin, and does not receive extra doses (from other members of the family who may not know the insulin was given), record the time of each insulin injection on a designated calendar.

  1. When giving your pet an insulin injection, you may, at first, want someone to help you hold and/or distract the cat while you are giving the injection. Usually cats do better if they are not held tightly. Scratching a cat on the head, getting her attention with a toy, or placing an enticing treat (very small piece of cooked chicken) near her nose may help focus her attention away from the injection. The needle is extremely thin, and the injection almost painless.
  2. Remove the needle guard from the syringe filled with the appropriate dose of insulin.
  3. Giving an insulin injection to a catIf you are right-handed, hold the syringe in your right hand. With your left hand, pick up fold of skin along your cat's back or shoulders (use a different site every time). Some veterinarians recommend giving the injections under the skin on the sides of the chest and abdomen, since it may be better absorbed from these sites.
  4. Push the needle through the skin at about a 45º angle. Be careful not to push the needle through the entire fold of skin and out the other side, or accidentally into your finger.
  5. Pull back slightly on the syringe plunger to be sure the needle is not in a blood vessel (if it is, blood will enter the syringe as you pull back the plunger), and then administer the insulin by pushing the plunger with your thumb.
  6. Withdraw the needle from the cat's skin, and replace the needle guard.
  7. Reward your pet by scratching his/her head (if they like it!), giving them a very small piece of cooked chicken, and talking to them. (Once you are more comfortable giving your pet injections and do not have to concentrate on what you are doing quite so hard, talk to them throughout the procedure.)
  8. Record the time of the insulin injection on the designated calendar.
  9. Needle/syringe disposal boxPlace the needle and syringe in a puncture-resistant container. These are available, sometimes free of charge, from your veterinarian or pharmacist. Follow your local regulations regarding disposal.
If your pet does not receive the entire dose of insulin, (e.g., some leaked out of the injection site, the needle went through the entire fold of skin and the dose was injected into the air, etc.) do NOT, we repeat, do NOT give more insulin. Wait to give more insulin until the next scheduled dose. Occasional missed doses are easily tolerated, overdosage can be fatal.

References and further reading:

Ellis, CJ. Diabetes decisions. Veterinary Forum; September 2008:26-34.

Feldman, EC. Diabetes remission in cats: Which insulin is best? Supplement to Compendium: Continuing Education for Veterinarians; 31(7A).

Hess, RS. Diabetes mellitus. Part 1: Diagnosis. NAVC Clinician's Brief; October 2009: 9-11.

Hess, RS. Diabetes mellitus. Part 2: Treatment. NAVC Clinician's Brief; November 2009; 21-24.

Kintzer, P; Monroe, E; Scherk, M; Scott-Moncrieff, C. Managing the diabetic cat. NAVC Clinician's Brief; July 2008 Supplement; 2-7.

Rios, L; Ward, C. Feline diabetes mellitus: Diagnosis, treatment, and monitoring. Compendium: Continuing Education for Veterinarians; December 2008:626-640.

Scherck, M. Managing diabetes mellitus in cats: What makes it work? Clinical Edge; June 2008:3-7.

Schermerhorn, T. Treatment of diabetes mellitus in dogs and cats. NAVC Clinician's Brief January 2008:35-39

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