Susie, Diabetic Cat
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Susie's Insulin Injections

Once Susie was diagnosed diabetic in 1999, I began giving her regular injections of insulin.  These started in October 1999 following a short period when she was given tablets that were ineffective.  Initially, her injections were once daily, but this was very soon to the more usual twice daily regime.

A key message here is that the thought of giving daily or twice daily injections is extremely daunting at first, but with the benefit of the experience of injecting a cat who could be very feisty, injections into the scruff of the neck are far less invasive and so much easier than trying to administer a tablet.

I began by giving her 1 unit per injection, and gradually increased the dosage, working closely with my vet during that initial period, in response to two key signs - her urine glucose and the amount of water that she was drinking.  This method was exceptionally slow in stabilising Susie, which later became a factor when I decided to change to a different practice, but it taught me a lot about the need to make small changes and then to wait for things to settle down.

On the right are various illustrations of the syringes that I use.  Early in 2005, I became aware that that this brand of syringe was available in 0.5ml size (20 units).  Previously they were only available in 1ml size (40 units).  I found the smaller syringes to be far better, making it much easier to administer the correct dosage accurately.  This is, of course, based on the relatively small dosages that Susie needed.  For larger animals requiring higher dosages, the 1ml syringes might remain the better option.

I normally aimed to inject to an accuracy of 1/4 unit.  This might seem unusually precise, but with injections of 2 units for example, a change of 0.25 is over 10%, a figure that I had seen recommended on other websites as a maximum change.  I have been asked whether it is possible to inject as accurately as this.  Whilst it might not be possible to be absolutely precise, I believe that I could reasonably estimate 1/4, 1/2 and 3/4 gaps between the unit markings, even on the larger syringes.  After switching to the smaller 20 unit syringes, this was much easier.  The fourth picture on the right illustrates the 20 unit syringes filled to 2-3 units in 1/4 unit increments.

• In some of the graphs there are periods where it looks as though her dosage was constantly cycling by 1/4 unit.  This is simply where I decided to change her daily dosage by 1/4 unit, so that her morning and evening injections were slightly different.

• Variable (whenever I got a sample) - sometimes more than 1 per day, or could be several days between samples.

• If the urine glucose reading fell between 2 of the colours I simply took an average.  If the colour on the stick reached the highest point, I took this as 2% if it took the full 30 seconds.  If it reached 2% more quickly I estimated a higher figure (e.g. I assumed 2.5% if it only took 25 seconds).  Whilst this was only a rough approximation, it illustrated more effectively where Susie's urine glucose was clearly high.

• Throughout October and most of November, I was gradually decreasing Susie's insulin dosage in response to urine glucose figures that were generally zero.

• The sudden drop at the end of November was from when Susie was ill with 6 injections disrupted - 3 missed out completely and 3 at reduced amounts to gradually bring her back up to normal.  This caused her urine glucose levels to rise slightly, with corresponding increases in her insulin dosage.

• There was also a single missed injection over the Christmas period which I regarded as a safer option than risking giving her one injection several hours early or late.