Diabetes mellitus is one of the most common hormonal medical conditions in cats.   Sometimes referred to as sugar diabetes, diabetes mellitus is caused by a lack of insulin.   Insulin is required to regulate glucose in the body and in the absence of insulin the cat will become hyperglycaemic.
This is mainly seen in middle-aged and older cats and is more common overweight cats.   Some breeds of cat have also been shown to be more susceptible, e.g. Burmese.  The following gives more information on the disease, including signs and treatment options ...

An endocrine disease

Insulin is normally produced by the cat's pancreas organ and is important for the control and use of blood glucose, i.e. sugar.  

Insulin is produced and passed into the blood when an increase in blood glucose is detected.  In normal situations this allows the body's cells to take up the glucose and use it for energy and help maintain normal levels of glucose in the cat's blood.

If insulin is deficient the amount of glucose in the cat's blood will increase, without any uptake by the body's cells.  The body still needs an energy source so will depend on other sources, e.g. breakdown of the cat's own fat cells.   

Diabetes mellitus can be diagnosed easily and with the treatments available, managed successfully.   Diabetes can occur secondary to other diseases but this will be investigated as part of your cats diagnosis.

Common signs
  1. Increased urination:   An increase in blood glucose levels in the bloods means that glucose is passed into the cat's urine drawing water with it.  The result is more urine production and the cat needing to go the toilet more often - known as polyuria
  2. Increased drinking:   As more water is being lost because of this increase in urine production, the cat becomes thirsty and will drink more - known as polydipsia
  3. Weight Loss:   The cat is unable to use the energy taken in by their food, so fat reserves are broken down.  Over time this can lead to weight loss.
  4. Increased appetitie:   This isn't always present but can be quite marked in some cats - known as polyphagia
  5. Other signs:   The following can be associated with diabetes mellitus, though can vary between individuals:  enlargement of the cat's liver which may be felt during veterinary examination; weakness, especially of the hindlegs caused by damage to the nerves; bacterial cystitis secondary to diabetes, (this can present by your cat straining to urinate and/or passing blood in their urine).   Most cats remain well in themselves but if a cat is left without treatment they may become depressed and develop vomiting , diarrhoea, anorexia and collapse - this becomes an emergency situation.

Testing is needed to confirm a diagnosis and to rule out other conditions that can cause similar signs.   A full veterinary examination will be followed by urine and blood tests.  

Urine testing will show the presence of glucose.   Ketones may also be present and are a sign that the cat has been using an alternative source of energy during the diabetes.   (Urine testing will also identify if the cat has a urinary tract infection, secondary to this condition.)

In the case of diabetes mellitus, blood analysis will show a high concentration of glucose. Fructosamine levels may also be tested and shows if the condition has been prolonged and not simply caused by the cat being stressed.  


This is usually a very treatable condition, but needs the dedication and commitment from the cat's owners.   In principle it involves dietary management and insulin injections alongside close monitoring.

Dietary management forms an important part of the treatment plan.  If the cat is overweight or obese a diet plan is needed to regain their optimum weight - this in itself can resolve the cat's diabetes as obesity can interfere with the action of insulin.  It is important that close monitoring takes place during this time - glucose levels need to be checked as the dieting cat's insulin levels will change.   Our nurses can help your cat achieve this with a combination of a reduced calorie diet and exercise program tailored to your cat.  

Once the cat has reached their optimum weight or if they are already at their optimum weight, a diet high in protein and very low in carbohydrates is used in combination with insulin injections.   Again our nurses can advice you on this, the diets we recommend and how to switch their food.

Insulin injections will be needed to manage the cat's diabetes in most cases, this may be prescribed once or twice a day.   Our nurses will show you how this is done and help you practice safely until you feel confident to do this on your own cat.  The insulin needles are very small and usually painless when injected under the skin, on the scruff of the cat's neck.

For a short video on giving your cat an insulin injection click here

Stabilising a cat with diabetes mellitus

It may be necessary to hospitalise the cat for initial stabilisation.  The cat can be given insulin and have regular blood tests to monitor the effect on it's blood glucose concentration.  This close monitoring will give us the chance to adjust the amount of insulin given and have a good control of the cat's condition before it is sent home.   This can be achieved on an out-patient basis but will mean frequent trips for blood glucose testing and ultimately it will take longer to stablilise your cat.  You will be given all the information you need before deciding the best route for your cat.  If they are to be admitted it is important that your cat is comfortable when away from home and we can advice you how best to do this.   We would also ask the following questions:
  • (If treatment has already started: How much insulin are they currently on and when was it last given?)
  • What is your cats appetite like? 
  • What is your cat currently eating and when did they have their last meal or something to eat?
  • What are they like generally at home?
  • Do you have any concerns?
Going home

When we are happy that your cat is stabilised and can go home we will spend as much time as needed to help you prepare for their ongoing needs at home.   It is important that their daily needs are kept as strict routines - e.g. feeding times, type of food and amount of food; activity and exercise.  Your cat's weight will need to be monitored as variations in their weight will fluctuate which can affect their insulin needs.

We will need to monitor your cat intermittently to make sure they remain stablised, you will be advised of this but it will include retesting the cat's urine and blood, their general health status and weight.   

Collecting urine from your cat is easy - we will give you special non-absorbent litter and a collection pot.  This litter should be used in a clean litter tray and the urine collected and brought to us as soon as possible.  If you have more than one cat, your diabetic cat will need to be kept separate until they have passed urine.

When your cat goes home they will be sent home with their own diabetic chart for your to complete on a daily basis.   This is to monitor: the insulin your cat is given; their demeanor (graded 1 - 5) e.g. more sleepy or lethargic than normal; their food and water intake (noting is this is increased / normal or reduced) and any other comments you wish to record.   

The following advise will help you care for your cat:
  • Eating   Unless told otherwise you can continue to feed your cat however you do normally, they can be fed adlib or structured twice daily feeding but if you feed twice daily it needs to be 12 hours apart. It also needs to be the same amount at the same time every day. Please feed your cat before injecting the insulin. 
  • Drinking   You may have noticed that your cat has been drinking more recently, this will settle down once they become more stable on their treatment. We ask that you monitor their drinking as much as possible, so if you only have one pet, measuring would be ideal. If not then just monitor how much time they are at the water bowl/tap. 
  • Demeanor    This is not something that we can monitor at the practice so we ask for you to keep a watch on how they are doing in themselves. We scale this on a 1-5, 1 being poor and 5 being 100% normal. Be aware that it is what is normal for your cat, this may be sleeping all day. 
  • Insulin     Injections are to be given 12 hours apart, although you can give up to an hour earlier or later. If it is going to be longer or shorter than this then do not give the insulin and just wait until the next injection is due. The insulin is to be kept in the fridge at all times. DO NOT SHAKE THE INSULIN. When you get the insulin out to draw up your cat’s dose gentle agitate the bottle to get it to combine. Once you have drawn up the dose then inject straight away. The insulin is a prescription medicine and we require 48 hrs to re order. 
  • Syringes and Needles     Insulin is injected using specifically manufactured insulin syringes.  The needles are permanently attached and are for single use only.   The insulin syringes Needles are to be used once.  The needle should be recapped safely and the whole syringe stored in a sealed container (e.g. ice-cream tub).  We can dispose of the insulin syringes if you bring them back to us.
  • Glucogel     You may be sent home with a tube of Glucogel, this is to be used if you suspect your cat is having a “hypo”. This may look like any of these symptoms; lethargy, collapse, muscle tremors/twitches, vomiting, appearing “not with it/drunk”. The gel is to be put directly onto the gums and ring the practice immediately. 
  • Complications     Such as vomiting, not eating, or signs of a “hypo” then do not give any insulin and ring the practice immediately.
Hypoglycaemia - low blood glucose concentration

This can occur if too much insulin in given and is life-threatening.   Signs include general weakness, disorientation, the cat may appear drunk and this can progress to collapse, seizures and a coma.  You need to contact us immediately.  It is a good idea to have a small bottle of glucose syrup in the house if you have a diabetic cat, for this very reason.  A small amount of this can be rubbed on their gums and will be absorbed quickly into the cats system.  We will advice you about hypoglycemia and what to do if this emergency was to occur.


The long-term prognosis will vary depending on how well the cat is stablised and if the cat is suffering from other conditions, but generally patients will cope for years with an excellent quality of life with daily care from their owners and regular contact with their vet and nurse.  This ongoing contact is necessary to regular examine and evaluate their status. 

If you have any concerns at all please do not hesitate to ring us: 01376 325511.

For further information on cats and diabetes, visit the International Cat Care (ICC) website diabetes page click here

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