Storage and Handling
In the insulin vial, the insulin is supplied as a suspension in water and it will settle out over time. It needs to be handled sensitively. Here are some tips, a combination of good ideas that I've read elsewhere and from my own experience:
Timing of Injections
Ideally, insulin should be injected immediately before feeding, but in practice it is safer to ensure that the cat will eat first. This is so the dosage can be reduced slightly if the cat chooses not to eat, or appears unwell. Any reduction in dosage for this sort of situation is a matter of judgment. Susie's hypos were all because she had been unwell and had either not eaten, been ill, or both.
The timing of insulin injections (which reduces blood glucose) relative to feeding (which raises blood glucose) is critical. If timed correctly, a fairly consistent BG level can be maintained. If not, there can be dangerous variations in the BG. There is an excellent set of graphs illustrating this on the Pets With Diabetes site.
If a cat is going to become hypoglycaemic after an injection, it is most likely to happen during the peak time of the insulin activity. Typically this might be around 6 hours after injecting. It is worth being aware of when this might be, in relation to the normal daily routine, as it might coincide with being out of the house or asleep.
At first, the thought of giving injections is is often very stressful for pet owners and I was no exception, but Susie quickly learned to accept her injections as part of a normal routine. From my experience, injecting is much easier than trying to give her a tablet. I tried to establish a very recognisable routine with a treat and this approach has worked consistently well over the years.
Two excellent sets of injection tips are available on the Feline Diabetes and Pets With Diabetes websites. Other websites also have excellent tips and there is even a video on one of the Caninsulin websites (see links page).
Injections are subcutaneous (i.e. under the skin) so the insulin takes a short while before it begins to reach the blood (the 'onset' time). The normal injection site is the scruff of the neck.
Insulin is measured in "units" (24 units=1 mg of pure insulin).
It is normally supplied as a suspension. The most common concentrations are 40 units per mL, 50 units per mL or 100 units per mL. These might be written in slightly different ways, for example: 40iu/mL; 40iu; U40; U-40.
Insulin syringes are marked in units rather than in mL which makes it easier to avoid errors, but it is important to use the right type of syringes (U-40 syringes for U-40 insulin, U-100 syringes for U-100 insulin, etc). Otherwise, the differences in strength between the insulin and the syringe markings have to be taken into account. This should always be avoided because it would mean giving a dosage that looks incorrect on the syringe and it increases the chance of a potentially dangerous error.
The picture on the left illustrates
syringes for U-40 insulin. They are 0.5ml syringes marked in insulin units so
that the scale on the syringe is from 1 to 20. This is the type
of syringe that I used to inject Susie's insulin.
Different types of insulin are designed to work at different speeds. This can be quite difficult to fully understand at first, but most vets should have experience of different types, so they should be are able to advise which type to try first. It is common for a bottle of insulin to contain a mixture of two different types. The 3 speeds used in the treatment of animal diabetes are:
Not all insulins are compatible with each other, because they may contain different types of stabilisers, so it is important to use mixtures that have been prepared by the manufacturer or compounded professionally.
There are 3 stages in the activity of all types of insulin:
As a rough guide, the following is typical of figures that I have seen on other websites for the time for different stages of each type of insulin, although there was some variation between the figures on the different sites (Sugarcats, Pets With Diabetes, Canine Diabetes).
Veterinary insulin is manufactured from a range of sources. Each source produces an insulin that has slightly different characteristics from the others. Sometimes, individual cats can be more suited to insulin one particular source rather than another. To a large extent, it is a process of trying different types to find one that seems to work well, so the experience of the vet might be a key factor.
Insulin is a natural hormone and veterinary insulin can be manufactured from different animal sources, for example beef (bovine) or pork (porcine) or it can be made genetically. Chemically, beef insulin is closest to that of cats, but it doesn't necessarily follow that cats will always do best with bovine insulin.
For Susie, I used a brand called Caninsulin supplied by Intervet, which is a U-40 intermediate (Lente) insulin. It is a mixture of 2 pork based sources, 30% Regular (Semi-Lente) and 70% Long Acting (Ultra-Lente). As far as I am aware, Caninsulin is not currently available in the USA, although it is available throughout Europe and in Canada.
Purely for background, here's a bit on the chemistry of insulin. As a hormone, insulin is made up of a series of amino acids arranged together in a chain. In all sources of insulin, most of the structure of the chain is identical, but there are a few small differences at specific points along the chain. As mentioned above, beef insulin is the closest to that of cats. This is because it differs by only 1 amino acid (i.e. only one point on the chain is different). Pork insulin differs by 3 amino acids and human insulin by 4 amino acids. If you'd still like to know more, there is a page on the Pets with Diabetes site that illustrates the amino acid sequence of insulin. Beef insulin is illustrated with a table summarising the differences for pork, cat, dog and human insulin.
Important note: All information and opinion in the Susie, Diabetic Cat pages is from personal experience. Nothing in these pages is intended to be a substitute for proper professional advice, which should always be sought from a qualified veterinary surgeon.
was last updated