Cats are quite different from humans – four legs, much more fur and a tail! But they can get many of the same diseases we get, such as diabetes. Today we will be discussing what diabetes in cats is, how vets diagnose it, and how we can treat it. 

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What is Diabetes in Cats?

‘Diabetes’ usually refers to the disease diabetes mellitus (there is a condition called diabetes insipidus which is a disease of the urinary system). In short, diabetes mellitus is a condition where the body does not react in the correct way to insulin.

Insulin is a chemical produced by the pancreas to control the body’s blood sugar (glucose) levels. When a healthy cat eats, glucose is absorbed into the blood. This raises the cat’s blood glucose levels. The pancreas detects this and releases insulin. Insulin acts on the muscles, liver, kidneys and other organs to convert glucose to its storage molecule glycogen. Insulin thus lowers blood glucose and helps store glucose for later use. After eating, glucose is also carried into the brain by insulin which tells the body to stop feeling hungry to avoid increasing blood sugar levels again. Insulin also increases the storage of fat and protein.

Type I diabetes mellitus 

(Rare in cats) is where the pancreas stops producing insulin altogether, allowing blood glucose to get dangerously high. It can be caused by chronic pancreatitis, immune destruction of the pancreas, or chronic high blood glucose in cats.

The more common type II diabetes mellitus 

This is where insulin is still produced but the body does not respond to it effectively. There is ‘insulin resistance’. This also results in high blood glucose. In cats, it is most commonly caused by obesity, but can also be linked to the use of certain drugs like steroids, pancreatitis, cancer and some genetic diseases. Long-term type II diabetes can progress to type I in some cases, and this is thought to be more common in cats than in humans.

Obese cats over 7 are most likely to have diabetes. Exotic breeds, such as Burmese, Tonkinese and Norwegian forest cats are also more prone to diabetes. Cats with chronic pancreatitis or other inflammatory diseases, or on long-term steroids are also at risk.

What Are the Consequences of Diabetes in Cats?

Cats with diabetes mellitus have high blood glucose. This causes a number of issues. The kidneys are unable to reabsorb all the glucose, leading to sugary urine; however, this also removes too much water from the blood, resulting in dehydration. This leads to increased urination. To compensate many cats will drink more too. High glucose in the blood also means less is in storage as glycogen, ready to be used for energy. As a result, cats’ bodies have to use stored fat and protein for energy instead. They start to breakdown muscle, resulting in weight loss and muscle wastage. 

Diabetic cats will also eat more 

This is because insulin cannot transport glucose into the brain to reduce appetite. Some cats will have a ‘plantigrade’ stance, where they drop their back legs flat when standing – look for ‘lameness’ or a strange gait. Other general signs to look out for are lethargy and weakness, depression, poor fur quality, smelly breath, stomach pain, neurological signs, smelly wee, painful urination and cloudy eyes.

Finally, cats with diabetes can enter a condition called diabetic ketoacidosis (DKA). 

This is where the body cannot use glucose for energy (as insulin does not help it enter the cells), so fats are used. Chemicals called fatty acids and ketones are produced as by-products. These cause dangerous acidic blood, dehydration, a rapid breathing rate, vomiting and diarrhoea. If untreated, DKA can be fatal.

To sum up… 

A cat with diabetes may;

  • drink and wee more
  • lose weight while eating more
  • have a funny stance
  • be slow and depressed
  • have poor hair, breath and eyes
  • show signs of pain.

If diabetic ketoacidosis develops, they can become dehydrated, vomit and have diarrhoea, collapse and even die.

How Do Vets Diagnose Diabetes in Cats?

Unfortunately, diabetes is sometimes first diagnosed when a sick cat is brought in with diabetic ketoacidosis. In these cases, a vet will look at the clinical signs and observe the cat is dehydrated. Blood tests will show high blood glucose and ketones, acidic blood, dehydration and high liver enzymes. Urine testing will also show high glucose and ketone levels.

Luckily, diabetes in cats is often identified early. Most commonly after an owner mentions their cat is drinking and weeing more and has lost weight. In this case, blood and urine will again show high glucose levels. However, glucose can be high for a number of other reasons, including stress (such as from a nasty vet poking them!), making it tricky to know if a cat has high blood glucose because of diabetes or something else. Glucose can also fluctuate during the day and a vet may sample the cat’s blood but miss the window when it was excessively high.

To compensate for blood glucose fluctuations, a chemical called fructosamine can be measured – fructosamine shows the average blood glucose level over the past few weeks. High fructosamine indicates that glucose has been chronically high – this is a much more accurate indicator of diabetes than glucose alone.

How Do Vets Treat Diabetes in Cats?

Well, it depends what state the cat is in.

Diabetic ketoacidosis in cats is an emergency so requires hospitalisation. 

Vets will provide fluids to reduce dehydration, insulin and potassium to encourage glucose to enter cells, pain relief, anti-sickness drugs and nursing care. It can sometimes take many days to stabilise a cat with DKA.

Treating non-emergency diabetes starts with insulin to lower blood glucose. 

Cats will require insulin daily (often twice a day), usually injected under their skin. Vets can show owners how to do this at home. Dosing insulin involves a lot of trial and error, so we usually start with a low dose of insulin and check the glucose level after – if it is not low enough we increase the dose. The ideal is to get a cat onto a dose that keeps their glucose level just right. It can take many months to get this correct dose. A cat with diabetes will require insulin every day for long-periods or even the rest of its life. This can be difficult for many owners to manage. Unfortunately, some cats may have too much insulin resistance and do not respond well to given insulin. 

It is also important to manage a diabetic cat’s weight 

As we said before, most diabetes in cats is caused by obesity. It is crucial to reduce a cat’s weight to help reduce insulin resistance. However, rapid weight loss can cause liver damage so it must be slow and guided by a vet. Weight loss mainly involves reducing food intake and increasing exercise, both of which can be tricky in cats. A diabetic cat’s diet should be low in carbohydrates to reduce glucose intake, high in protein to encourage muscle recovery, and ideally wet to improve hydration. Many pet food companies sell pet food designed for diabetic cats. 

Owners at home should monitor their cats 

Look out for their demeanour, water intake and urine output, appetite, weight and body condition and insulin dosing. It can be a great idea to keep a ‘diabetic diary’ for this. It is also good for the owner to record how they are managing – diabetes is a challenge and it is important owners are comfortable too. The cat should also visit the vets regularly for check-ups and to monitor blood glucose.

Finally, owners should look out for signs of low blood sugar

This can occur due to the insulin dose being too high and reducing blood glucose too far, or a condition called diabetic remission where the body starts to respond to insulin again. Low blood glucose causes lethargy, tremors, anorexia, vomiting, difficulty walking, seizures and even death if not treated. Owners should prepare by having glucose or honey to give to their cat to quickly raise their blood sugar again, before taking their cat to the vets.

How Long Does a Cat with Diabetes Live?

It really varies. A cat with diabetic ketoacidosis can die quickly while a well-managed diabetic cat on insulin can live for years. Generally, the earlier diabetes is diagnosed the better the prognosis. A cat can even enter diabetic remission and start to respond to self-made insulin again. 

However, diabetes is not a simple fix and usually cannot be fully cured. Vets should inform owners of the treatment involved, the cost, the time necessary to put in, how lifestyles may have to change, and offer help where needed. Owners should be encouraged to ask for help or support. 

It is also important to consider whether you or your cat may be struggling with diabetes, and may have to consider putting them to sleep. 

This is an incredibly hard decision, so we encourage owners to ask their vet for advice. If they think their cat is in pain, struggling to eat, drink or toilet, losing a lot of weight, or otherwise having more bad days than good, they should consider saying goodbye at their next vet visit. An owner’s well-being is just as important, and although we know many owners would give the world for their cats, it is important to look after our own health too. There is no shame in an owner admitting they are struggling with a diabetic cat in any way, including financially.

Final Thoughts

We hope this guide has explained what diabetes mellitus is in cats, what it does to a cat, and how we diagnose and treat it. If you are the owner of a diabetic cat and have further questions, please comment below or ask your vet for further advice and assistance.

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