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Feline Diabetes Insulin Therapy Fact Sheet

Information for pet owners on administering insulin therapy for the treatment of diabetes in cats.

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How is insulin administered to cats with diabetes mellitus?

In cases of standard diabetes where the patient is otherwise relatively healthy, cats will generally be started on insulin injections immediately once the diagnosis is made. Because they break down insulin relatively quickly, almost all cats will require injections twice a day (morning and evening, roughly 12 hours apart, at the same times each day). The injections are usually administered under the skin of the back using either a syringe and very fine needle or a purpose-designed insulin pen. A crib sheet on insulin administration is also available within the fact sheet section of the Davies Veterinary Specialists website.

Insulin is typically started at a low dose, which will often need to be gradually increased based on response. The low dose is used because overdosing of insulin is much more dangerous than underdosing, but the consequence is that it can take some weeks to reach the optimal dosage by incremental increase. Insulin doses should not be changed too regularly (3-5 days is required for a new dose to show its full effect) and doses should never be altered without discussion with a vet.

How will my cat respond to regular insulin injections?

Typically, cats tolerate the injections very well and do not find them to be uncomfortable. This is due to the tiny width of the insulin needles and the fact that they have a large amount of loose skin which is not painful to inject under (unlike in humans). This comfort can be maintained in the long term by varying the site of injection across different areas of the back. This prevents one area of skin being consistently pierced, which eventually would lead to the development of inflammation. Anywhere that you can find loose skin is an acceptable place to inject.

What happens if my cat misses an injection?

In view of the fact that an overdose is significantly more dangerous than an underdose, there are some important principles where insulin management is concerned.

  1. If there is any uncertainty about whether the dose has been given or whether the full amount of insulin was correctly injected, DO NOT repeat the injection. A single missed dose is far preferable to the risk of a double dose.
  2. If a dose is missed, wait until the next time the insulin is due and administer the normal amount. Do not be tempted to give a dose (full or part) in the meantime as this will lead to more instability.
  3. If your cat becomes unwell, is vomiting or is refusing to eat, DO NOT give insulin. The amount of insulin required is related to how much food is eaten, and so if no food is eaten for more than a 12-hour period (when normally it would have been expected to have been eaten) and is refused when offered, do not give the insulin and contact your vet for advice. They may recommend either skipping the dose, giving a part-dose or that your cat should be examined at the practice.

An overdose of insulin can lead to low blood glucose (also referred to as hypoglycaemia or ‘a hypo’). Often this leads to no clinical signs and does not cause a significant problem, however, if blood sugar drops too low it can result in weakness, lethargy, poor responsiveness to people or the environment and strange behaviours, and can progress to collapse, coma and death if untreated. Should any of these signs occur, a sugary substance such as honey or golden syrup should be rubbed on the cat’s gums to rapidly increase blood sugar and your vet should be contacted immediately.

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