Cat Diabetes: Causes, Signs, Diagnosis, Treatment
When a cat is diabetic, it means he has too much circulating glucose (sugar) in his bloodstream because his body is unable to make insulin (Type 1 diabetes) or his cells do not respond to insulin (Type 2 diabetes). Type 2 diabetes is the most common form in cats.
Insulin is a hormone that allows glucose to be taken up by cells from the bloodstream and allows it to be stored in various forms. When there is not enough insulin or the body does not respond to insulin, too much glucose remains in the bloodstream. When glucose is at normal levels in the bloodstream, the kidneys are able to reabsorb it so glucose is not found in the urine. In a diabetic animal, the kidneys are not able to reabsorb all the extra glucose and the glucose is spilled into the urine. The glucose in the urine pulls more fluid with it, so the cat produces more urine, which results in fluid loss and creates thirst in the cat.
Signs of diabetes in cats
The most common sign of diabetes is an increase in thirst and urine. Other common signs include an increase in appetite and weight loss. Increased appetite is especially true in the early stages of the disease. The cat’s cells are not able to use the glucose in circulation, so they send signals to the brain that create an increase in hunger. As the disease progresses, many cats actually lose their appetite because of a series of secondary effects on the body.
Weight loss happens because the cat is not absorbing nutrients. Insulin also helps with the building of proteins, so not having or not being able to use insulin results in less protein production and less muscle mass.
Additional common signs of diabetes include dehydration, weakness, a rough hair coat, a distended abdomen and a plantigrade posture (i.e., the cat’s ankles are low to the ground).
Diagnosing feline diabetes
As soon as any of the above signs are noticed, the cat should be taken to a veterinarian. If the cat is eating and seems mentally normal, it is not typically necessary to go immediately to an emergency clinic. However, things can change relatively quickly with diabetic cats, so it is not advisable to wait several days.
Even though there are classic signs of diabetes in cats, other diseases can act the same way. Kidney disease, an overactive thyroid gland, liver disease and urinary tract infections can all have similar presenting signs and look the same outwardly to the veterinarian. So, to actually diagnose diabetes, the veterinarian will have to perform blood tests and a urinalysis. The blood will show an elevated glucose level and the urine will have glucose in it.
Diabetes cannot be diagnosed simply on an elevated blood glucose because a cat’s glucose level can go up significantly due to stress. The trip to the veterinarian’s office and the drawing of blood can be enough to increase a cat’s blood glucose level. However, the glucose typically does not spill into the urine with such a quick spike. That’s why, to diagnose diabetes, both a blood test and a urinalysis are needed.
There is another blood test that can be used to determine if a cat’s blood glucose has been elevated for longer than the time period of the stressful event. This test measures a cat’s level of fructosamine, a protein that has glucose attached to it, and can give the vet an idea of what a cat’s blood sugar has been over the last 1-2 weeks. It can be used to confirm a diagnosis of diabetes, but is more commonly used when obtaining a urine sample is not possible. Some cats come to the veterinary office with an empty bladder, empty their bladder on the way to the office, or just will not allow a sample to be taken.
Causes of Type 1 and Type 2 cat diabetes
There often isn’t one direct cause of diabetes. It is more appropriate to talk about what factors predispose a cat to develop diabetes. The biggest factor under our control is a cat’s weight. Overweight cats secrete too much of some hormones and not enough of others, causing the body to not respond as well to insulin.
Feeding a high-carbohydrate diet can also predispose a cat to becoming diabetic. Cats are obligate carnivores and their metabolism is geared toward a diet that’s high in protein and low in carbohydrates. Eating too many carbohydrates leads to chronically elevated blood glucose levels, which can lead eventually to lower insulin secretion, causing glucose levels to go even higher. A low-carbohydrate diet is more easily achieved with canned food rather than kibble. (Note: Contrary to some popular misconceptions, canned food has not been shown to lead to worse dental health for cats.)
Other diseases that are untreated can also predispose a cat to diabetes. An overactive adrenal gland, an overactive thyroid gland, a chronically inflamed pancreas and acromegaly (a condition in which the pituitary gland produces too much growth hormone) can all contribute to a cat becoming diabetic. In addition, male cats are more likely than females to be diabetic.
Treatment for diabetic cats
The mainstay of diabetes treatment in cats is insulin therapy. Insulin injections are typically given twice daily, though some cats do well on once-daily injections. The injections are given under the skin. Many people have concerns about giving injections to their cat, but with rare exceptions, cats tolerate the injections well, and even the most needle-phobic person is able to administer the injections.
Types of insulin
There are many types of insulin available. The one to use is often determined by the veterinarian’s comfort level with a particular insulin, the availability of different insulins and cost. Vets have their preferences based on what their experience has been, how they were taught and what insulins are available in their area.
Glargine (Lantus) insulin is often the recommended insulin for newly diagnosed, uncomplicated cases of diabetes in cats. It is thought that cats have the greatest chance of going into remission (i.e., they no longer need insulin therapy) if they are started out using Lantus insulin. One drawback is that this insulin is quite expensive. However, the fact that cats have the greatest chance of going into remission with this insulin may make it the most economical choice because it’s possible that the cat will not need to keep getting the insulin and going through the recommended follow-up visits.
Other types of insulin include NPH, Novolin N, Vetsulin, and PZI (ProZinc). Of these, PZI usually works the most consistently and has a longer duration of action, but as with Lantus, it is more expensive.
Oral diabetes drugs for cats
Oral diabetes medication, such as Glipizide, can be used, but most veterinarians prefer that cats be treated with injectable insulins. The oral medications do not work as well in cats, and it’s often easier for people to give a cat injections rather than pills. However, there are some circumstances in which oral medication may be used. Some people are very uncomfortable around needles, and some cats will not allow injections, but will eat the oral medication in food.
Diet change and weight loss
The other mainstay of diabetes treatment is diet change, an important part of possibly getting a cat to go into remission. Feeding a high-protein, low-carbohydrate diet allows the insulin to work better and helps the cat to lose weight. Canned food is better than dry food, since it is lower in carbohydrates, is not as calorie-dense and contains more fluid.
In conjunction with a change in diet, weight loss is a vital part of diabetes management. Weight loss is often achieved by feeding the cat a high-protein, low-carbohydrate diet, but it is also achieved by only feeding a certain amount of food at designated meal times. Feeding at select times also makes it easier to ensure that the cat will eat, which then allows insulin to be administered.
Exercise programs also help with weight loss and management in cats. Exercise can include taking the cat for walks using a harness and leash, having the cat chase toys or even encouraging the cat to “hunt” for his food if kibble is still being fed.
Treating other medical conditions
To help with diabetes control, any other disease conditions should be diagnosed and treated. Infections can lead to insulin resistance, as can other systemic diseases such as kidney disease, heart disease or overactive adrenal glands. Some of the most common interfering conditions include urinary tract infections and dental disease.
Natural or holistic therapies for diabetes
There are no proven natural or holistic therapies to treat diabetes. However, some veterinarians may use some holistic or herbal therapies that they have found beneficial. And, technically, switching the cat to a high-protein, low-carbohydrate diet is a “natural” treatment.
Untreated diabetic cats
If diabetes is left untreated, the cat will go into a condition call diabetic ketoacidosis (DKA). In essence, because the cat has not been able to use glucose for energy, he starts making ketones to be used for energy. As these ketones build up, the body can no longer function, and the cat will die without treatment. The treatment is usually 3-10 days of intensive hospitalization, usually in a 24-hour veterinary hospital. If the DKA is treated but therapy is not started to control the diabetes afterward, the same thing will happen again.
Important considerations when giving a cat insulin
No matter which type of insulin is used, it is vital that the cat eats before the insulin is given. It is much more dangerous for a cat’s blood sugar to drop too low than to stay elevated for an extra day.
The concentration of the insulin being used is also important, because there are different insulin syringes that are calibrated to work with different concentrations of insulin. The syringes are labeled for the concentration of insulin with which they should be used. If the wrong syringe is used, the cat may either be over-dosed or under-dosed.
Determining the optimal insulin dosage
Some veterinarians like to hospitalize the cat on the first day of insulin treatment to ensure that the cat does not become hypoglycemic (i.e., his blood sugar has dropped too low). If the cat’s blood sugar level does drop too low, the vet may elect to lower the insulin dose. Normally, insulin doses are not increased after this first day, as not enough time has passed for the cat to adjust to the insulin.
It can take weeks to find the correct dose of insulin. To determine if the dose needs to be changed, a veterinarian may do a glucose curve 7-14 days after the insulin is started. The cat will stay in the hospital and have his blood sugar checked every 2-4 hours to determine how low the glucose level goes and how long after the insulin is given it happens. Based on the results, the vet may alter the dose of insulin.
Alternatively, the cat’s person can perform the glucose curves at home with the use of a glucometer, an in-home glucose-measuring device. These are relatively easy to use and most people can become quite comfortable using them.
As discussed earlier, cats are prone to stress hyperglycemia, which means their blood sugar goes up when they are nervous. That stress reaction might have an effect on an in-hospital glucose curve, so it’s one reason to have the cat’s person do the glucose curves at home. The vet could also run a fructosamine level to get an idea of what the blood sugar has been over the last 7-14 days. This is a good idea for cats who are really stressed in the hospital and whose people are unable to perform the curves at home. However, a fructosamine level cannot tell how low the insulin goes nor at what time past the insulin administration is the low point in the blood sugar.
It is also important for people to monitor their cats’ clinical signs at home. An increase in activity and a decrease in weight, water consumption and urine production are indicators of response to therapy. If the lab tests are off, but the cat is acting a lot better, it may be possible to make smaller adjustments to treatments. People also need to look for signs of hypoglycemia (low blood sugar), including weakness, collapse, seizures, wobbliness, disorientation and excessive drooling. If these signs are noted, the cat should be given a little sugar water or Karo syrup and taken to a veterinary hospital immediately.
Prognosis for diabetic cats
The prognosis for a cat with diabetes depends on a number of things. Poor indicators of long-term control over the disease include other endocrine diseases such as an overactive adrenal gland and an overactive pituitary gland. If a cat develops ketoacidosis and cannot get out of this state, or is in this state during follow-up visits, there is a correlation with poor long-term survival.
For most diabetic cats, the ability of the cat’s person to manage him is the biggest factor when it comes to prognosis. For instance, if the person cannot consistently give the insulin, the cat tends to do worse and is hard to regulate. Also, if the cat will not eat a canned high-protein food, it is harder to get good control of his blood sugar.
It is not possible to cure a diabetic cat, but it is possible for the cat to go into remission. Being in remission means that he does not need insulin for four months. However, even in remission, a diabetic cat typically needs to stay on a high-protein diet. He also should have his blood sugar checked frequently and have an exam done by a vet to make sure he does not require insulin again.
Diabetic cats do require more extensive veterinary care, but those who have their blood sugar adequately managed can live for years.
Costs of caring for a diabetic cat
The costs can vary quite a bit from cat to cat. The variability in cost comes from the type of insulin used, concurrent diseases, if the cat’s person is able to do follow-up glucose curves at home, the cost of food, and how long a bottle of insulin lasts.
In general, expect to spend the following:
- Insulin: The cost ranges from $35 to $325 a bottle. Again, the more expensive bottle may actually be less expensive in the long run because less is needed and there is a greater chance of remission. A bottle will last anywhere from one to six months.
- Glucose curves: Depending on how the veterinarian elects to do them, the cost can range from $40 to $200 every 2-4 weeks until the cat is well regulated, and then every 1-6 months thereafter. Again, there is a lot of variability between veterinarians’ choices and individual cats’ needs. If the cat’s person elects to do the glucose curves at home, a starter glucometer kit (blood-measuring kit) costs about $40 to $50 and this kit will do up to 10 curves as well as some spot glucose checks.
- Concurrent diseases: In cats who have concurrent diseases, the vet may need to do follow-up urinalysis, full blood panels or even specialized endocrine testing.