Diabetes is estimated to affect 1 in 200 cats, and 1 in 300 dogs in the UK, although it may be under-diagnosed. In both species it’s said to be on the increase. According to a 5-year study of 900 pets by insurer Animal Friends started in 2011, cases of diabetes in dogs have risen by 850% and cats by 1,161%.

Diabetes is exceedingly rare in Guinea pigs and rabbits. Obesity is thought to be the major cause of these isolated cases so keeping your small pet a healthy weight is ideal. A high proportion of Chinese hamsters are born with a genetic predisposition to develop diabetes. 

Table of contents

We will concentrate on dogs and cats within this whistle-stop tour of diabetes. Although there is no cure, treatments for cats and dogs do exist. 

What is diabetes?

Diabetes is caused by a lack of the hormone insulin, or a lack of response to it. Insulin is produced by the pancreas and released into the blood after food. It allows glucose released into the bloodstream to be taken up by cells in the body and used for energy as well as keeping blood glucose levels steady.

Lack of insulin, or lack of response to it, means cells will not be able to use glucose efficiently for energy and blood glucose levels increase (hyperglycaemia). There are two main types of diabetes, and dogs and cats suffer it quite differently. 

Type-1 diabetes

This is the most common type seen in dogs and is due to failure to produce enough insulin. This is often because of irreversible damage to pancreatic cells by the immune system, but can be due to long-term inflammation of the pancreas, or end-stage type 2 diabetes. It’s commonly called ‘insulin dependent’ as pets require insulin injections for successful treatment.

Type-2 diabetes

Most common in cats, Type-2 diabetes occurs due to a combination of reduced insulin production, and insulin resistance (where cells do not respond normally to insulin). Over time the pancreatic cells become exhausted or destroyed. This ends in type-1 type diabetes, often the stage of diagnosis. There is a link between chronic pancreatitis and diabetes in cats.

Pets can suffer insulin resistance due to the effect of hormones, such as excess production of cortisol in Cushing’s disease in dogs, excess growth hormone production in cats, or progesterone in un-neutered female dogs. Unspayed females are twice as likely to become diabetic. Certain medication such as glucocorticoids can also cause resistance. In cats, insulin resistance is often due to obesity, which can increase chances of diabetes 4-fold.

In hamsters, diabetes appears to be related to an increased demand for insulin, exhaustion of supplies then a decrease in pancreatic cell mass causing a deficiency in insulin. 

What signs might my pet have?

Diabetic animals will urinate more and subsequently drink more to make up for lost fluid. As the energy in food is not used efficiently, pets will be hungrier but lose weight. Most animals develop cataracts. As cells are starved of energy, fat is changed into ketone bodies, an emergency fuel, creating by-products that can make animals extremely sick. This late stage is known as diabetic ketoacidosis and is fatal if not treated. These pets will be lethargic, have a poor appetite and may vomit.

How is diabetes diagnosed?

Diagnosis is done by simply looking for high levels of glucose in the blood and urine alongside the classic signs. In cats and other species, stress can cause high blood glucose. In cats, if in doubt, there is another lab test that looks at average glucose levels over the previous few weeks. Other tests to look for associated issues may be needed.  

How is diabetes treated?

Insulin

Most pets need twice-daily injections of insulin under the skin. Although this may sound scary, the needles are small, unnoticed by the pet, and are easy to give with practice and teaching. Some owners use an insulin pen, which makes it even easier. The dose is adjusted depending on your pet’s signs, urine, and blood results. It’s important to give the dose accurately as an overdose can cause an extremely dangerous, sometimes fatal, drop in blood glucose. Diabetic pets that show weakness or a drunken appearance immediately need sugar delivered orally followed by a veterinary assessment.

Diet

Diet can help enormously in diabetic control. Recommended diets for cats and dogs are quite different. A high-protein and low-carbohydrate diet is now thought most beneficial for cats. High-protein diets increase their sensitivity to insulin and cause less of a glucose spike after eating. Dealing with obesity is vital given the link with diabetes. In dogs we know stability in feed type and timing is vital. Type of carbohydrate is important and there is a debate about optimal fibre levels. Sticking to prescription diets recommended by your vet is the best idea. 

If your pet is really sick, they may require investigations and treatments as an inpatient. Pets may need tests for other related conditions such as Cushing’s disease if they do not respond to insulin as expected. If you have a female unspayed dog, then neutering will need to happen as soon as possible. Medications that may be impacting their sugar levels will need to be reviewed.

For hamsters, feeding a high-protein, low-sugar, low-fat diet, may help to prevent and control diabetes to a certain extent.  

The outlook

Treatment requires a huge time and financial commitment. 

Without treatment diabetes is eventually fatal. However if caught early and stabilised well, diabetics can have a good quality and quantity of life. If poorly controlled, diabetics can have a much-reduced lifespan and suffer complications that do impact on quality of life. 

If diabetes is managed well initially in cats, irreversible damage can be limited and, once rested, the pancreas MAY recover so remission is possible, with occasional cats not needing insulin long-term. This is rare. For dogs, other than with un-neutered females where neutering can occasionally lead to a remission of diabetes, dogs will need insulin injections forever. 

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