Diabetes in cats: a guide for pet parents

There are two forms of diabetes in cats: diabetes mellitus and diabetes insipidus. They are completely different diseases that affect different body systems. Diabetes mellitus is the most common type, causing elevated blood glucose levels and an inability to use sugar for energy. Diabetes insipidus is rare, and it affects how a cat creates urine in the kidneys. Both types of diabetes require a diagnosis to receive proper treatment from a veterinarian. If you are a cat owner, read on to learn:

• What are the two forms of diabetes in cats?
• What are the clinical signs of feline diabetes?
• Is my cat at risk for diabetes?
• How is feline diabetes diagnosed and treated by a vet?

The most common symptoms of both forms of diabetes are excessive thirst and urination. Cats with diabetes mellitus may also show weight loss and lethargy despite a good appetite.

There are two forms of diabetes that can develop in cats. Diabetes mellitus (DM), or sugar diabetes, occurs when the blood sugar levels in the body cannot be properly regulated because  either:

• The body is not producing enough insulin
• The body is not responding to insulin

Diabetes insipidus (DI) occurs when there are issues either producing or responding to antidiuretic hormone (ADH), which signals the kidneys to stop creating urine. When talking about diabetes, people are most often referring to diabetes mellitus because it is far more common than diabetes insipidus in both cats and humans.

Diabetes mellitus (DM)

Diabetes mellitus is the most common form of diabetes in cats. DM occurs when blood sugar levels cannot be properly regulated because either:

• The body cannot produce enough insulin (type I diabetes mellitus)
• The body is not responding to insulin (type II diabetes mellitus)

There is less of a difference between the types of DM in pets than in people, so veterinarians rarely refer to types when discussing DM in cats. However, type II is the most common type of diabetes mellitus in cats. A healthy body uses sugars, or glucose, as a main source of energy, and the hormone insulin created in the pancreas is needed to process them. When the body cannot utilize available sugars, it begins to break down fats and muscle tissue for energy instead. Clinical signs such as low energy levels, weight loss, and increased appetite occur as a result of the body not getting enough of these sugars for energy despite a high blood glucose level.

Diabetes insipidus (DI)

Diabetes insipidus is rare in cats. DI occurs when antidiuretic hormone (ADH) is either:

• Being insufficiently produced by the brain
• Not being absorbed by the kidneys

ADH regulates how much urine the kidneys make. Without ADH’s influence on the kidneys, urine is produced constantly, leading to dehydration and electrolyte imbalances. Severe dehydration has negative effects on nearly every part of the body.

DM and DI share some clinical signs, but because the two conditions affect the body differently, there are key differences in their symptoms. Symptoms of diabetes mellitus include:

• Increased thirst and urination
• Increased appetite
• Lethargy
• Unexplained weight loss
• Walking with hind limbs close to the ground

Cats with DM sometimes walk or stand abnormally with flat back feet (ankles touching the ground). Increased thirst and urination are almost always present, but not all cats will have other symptoms of DM, especially early in the course of the disease.

Signs of diabetes insipidus include:

• Increased thirst
• Excessive urination
• Lethargy

The most common signs of DI are increased thirst and excessive urination. Other symptoms, such as lethargy, tacky gums, or sunken eyes, are signs of severe dehydration, so they are more common in more advanced stages of the disease.

The first clues that a cat is developing either DM or DI may be finding the water bowl or fountain is empty more often than normal, and they may make more frequent trips to the litter box, flood the litter box, or have accidents around the home.

Is diabetes an emergency in cats?

Most cats with either DM or DI show obvious symptoms for weeks to months before the situation becomes an emergency. Ketoacidosis and hypoglycemia are complications of DM that can be emergencies. When the body breaks down fats as an energy source, chemicals called ketones are released into the bloodstream, making the blood more acidic. If too many ketones are released into the blood, ketoacidosis occurs, causing widespread dysfunction throughout the body. Symptoms of ketoacidosis include:

• Vomiting
• Loss of appetite
• Severe lethargy
• Acetone-like smell to the breath (similar to fingernail polish remover)
• Disorientation
• Seizures
• Yellow eyes, skin, or gums (jaundice)

Hypoglycemia, or low blood sugar, can occur as a result of medications used to lower blood sugar levels in patients with DM. Symptoms of hypoglycemia include:

• Weakness
• Vomiting
• Severe lethargy
• Lack of coordination
• Seizures

Severe dehydration can occur in patients with DI. Emergency symptoms of dehydration include:

• Sunken eyes
• Tacky or dry gums
• Severe lethargy

It’s crucial for cat owners to be aware of emergency symptoms and to seek veterinary help right away if they occur.

Diabetes mellitus is caused by insufficient production of or inadequate response to insulin. Associated conditions and risk factors for DM include:

• Obesity
• Hyperadrenocorticism (Cushing’s disease)
• Pancreatitis
• Increased age
• Sedentary lifestyle
• Long-term steroid use

Obese cats are four times more likely to develop DM than other cats, making it the greatest risk factor.

DI is caused by either inadequate production of the hormone that helps regulate the amount of water and salt in the body (ADH) or by a failure of the kidneys to respond to ADH. Potential causes, risk factors, and associated conditions for diabetes insipidus include:

• Trauma to the head
• Lymphoma
• Kidney disease or failure
• Medications such as steroids, certain anesthetics, and diuretics
• Brain or kidney tumors
• Infection
• Hyperthyroidism
• Congenital kidney abnormalities
• Acromegaly (a pituitary disorder)

However, DI is rare even in cats with a risk factor.

Is my cat at risk for developing diabetes?

Diabetes mellitus is far more common in cats than diabetes insipidus. Obese and senior cats are most at risk for developing DM. Many studies show male cats are also at a significantly higher risk than female cats. DI doesn’t have a known predisposition in any age, breed, or sex of cat.

Routine blood tests and urinalysis are typical first steps for any cat showing excessive thirst and urination to diagnose both forms of diabetes in cats. Diagnosing DM is usually a straightforward process when a cat has persistently elevated blood sugar levels and glucose in the urine. If there is no evidence of DM, additional diagnostic testing such as imaging or additional blood tests are performed to look for other more likely endocrine disorders such as hyperthyroidism. If a cat doesn’t respond well to insulin therapy for diabetes mellitus, acromegaly or another endocrine disorder may also be present. When everything else is ruled out, DI may be suspected.

If DI is suspected, a water deprivation test or ADH response test may be recommended. A water deprivation test involves measuring urine concentration levels, withholding water for a few hours, and then re-evaluating urine concentration. Cats with DI will continue to have increased production of dilute urine. Water deprivation tests must be done carefully and under a vet’s observation because withholding water can be life-threatening in some cases of DI. In an ADH response test, supplemental ADH is given, and urine concentration is remeasured. If the concentration increases, it points to a DI diagnosis. Therapeutic trials, which are clinical studies used to evaluate the efficacy of a treatment, may also be used to diagnose diabetes insipidus in cats.

“Diabetes mellitus and diabetes insipidus are two entirely different medical conditions that have nothing to do with each other,” explains Dr. Jo Myers, a veterinarian on the Vetster platform. “As a result, they are treated very differently.”

The goal of treatment for DM is glycemic control or maintaining healthy blood glucose levels. The treatment of diabetes mellitus involves:

• Insulin injections
• Weight management
• Special diet

Cats with well-managed DM sometimes go into remission, where they will no longer require insulin treatment. Cats who no longer need insulin but continue to receive insulin injections are at risk of hypoglycemia. It’s important to check a diabetic cat’s blood sugar levels regularly and talk to a veterinarian when things change.

Even cats in diabetic remission must maintain a healthy weight and stay on an appropriate diet. Diabetic diets are low in carbohydrates and high in protein to help regulate blood sugar. A cat with DM may need a strict feeding schedule, a daily routine at home, and regular blood sugar checks using a glucometer. Close monitoring with a vet is necessary to adjust insulin doses as needed.

Diabetes insipidus can originate in the brain or in the kidneys. The form of DI caused by the kidneys not responding to ADH has no treatment and cannot be cured. In DI that originates in the brain, treatment may not be necessary because some cats can live a relatively normal life simply by being allowed  unlimited access to clean, fresh water — as long as their corresponding excessive urination can be managed. It’s possible for DI due to a head injury to completely resolve over a couple of weeks as the injury heals. ADH supplementation may be given once or twice daily, and sometimes diuretics are beneficial. If the cat has an underlying condition contributing to DI, symptoms may lessen with successful management of that condition. Never withhold water from a cat with DI, as this can be life-threatening.

Does my diabetic cat require insulin shots?

The majority of cats with diabetes mellitus will require insulin therapy in the form of injections. Pet owners give the insulin shots at home, usually twice daily. The insulin dose and frequency of injections varies for each cat and can change over time. Failing to store, mix, measure, and administer insulin correctly can render it ineffective, so get specific directions from your vet. Insulin administration can result in hypoglycemia, which can be rapidly life-threatening, so close monitoring and communication with a vet is essential. An online vet can help walk you through insulin injections at home if you are unsure and need help.

Some cats with DM may go into diabetic remission and no longer need insulin shots. However, they still must maintain a healthy weight and have a high-protein, low-carbohydrate diet recommended by a veterinarian and a strict feeding schedule to prevent a relapse.

For cats with diabetes mellitus, follow a vet’s instructions on feeding and insulin administration. Always ask for help if you are unsure how to give insulin or what dosage your cat needs. For cats with diabetes insipidus, follow your vet’s advice on the right course of treatment, as it can vary between patients. For both types of diabetes, be aware of the signs of emergencies and keep a close eye on your cat. If you need help administering insulin or want advice on feline diabetes, veterinarians on Vetster are available 24/7 in online virtual care appointments.

How can you tell if a cat has diabetes?

The most common symptoms in cats with diabetes mellitus or diabetes insipidus are increased thirst and excessive urination. Cats with diabetes mellitus may also lose weight, feel lethargic, and have a ravenous appetite. Several different illnesses cause increased thirst and excessive urine production, so blood work, urinalysis, and other diagnostic tests are necessary to determine which illness the cat has.

Can feline diabetes be cured?

Diabetes mellitus cannot be cured, but some cats will go into diabetic remission and no longer require daily insulin injections. Diabetes insipidus caused by a head injury may resolve within a couple of weeks as the brain heals.

How long do cats live with diabetes?

Cats with diabetes mellitus, or sugar diabetes, can live a normal lifespan if the condition is well-managed and responds well to treatment. The prognosis for a cat with diabetes insipidus varies depending on the underlying cause. It may completely go away or be successfully managed by providing plenty of water and litter boxes. However, uncontrolled diabetes mellitus and severe dehydration from diabetes insipidus can be rapidly life-threatening.

Is a cat with diabetes in pain?

Other than showing excessive thirst and urination, cats with early diabetes mellitus or diabetes insipidus usually act completely healthy. Over time, diabetes mellitus in cats can lead to unpleasant symptoms such as lethargy, weight loss, and vomiting. Diabetes insipidus in cats can cause cats to become severely dehydrated. Cats with well-managed diabetes can often live normal lives and have a good quality of life.