The majority of cats diagnosed with diabetes require treatment with insulin, diet changes and lifestyle modifications. While diabetes is not a curable disease, with proper treatment, it is manageable. The goal of treatment is to resolve the signs of the disease, maintain a proper body weight, reduce the likelihood of any complications and provide the cat with a good quality of life.
The Decision to Treat
Treating a diabetic cat is not for the faint of heart, so not all owners of diabetic cats choose to pursue treatment. Before committing to a strict treatment schedule for the life of the cat, it is important that owners are well-informed about the treatment process and associated costs.
It can take as little as two weeks or as long as several months to regulate diabetes with insulin and diet changes in cats. During this time, frequent visits must be made to the veterinarian to test a cat’s blood glucose by means of a blood glucose curve or fructosamine blood test. With prompt and effective treatment, it is possible for some cats to go into remission.
With treatment, insulin must be given every 12 hours, at the same time each and every day, likely for the remainder of the cat’s life. Insulin is administered through an injection under the cat’s skin. When first beginning an insulin regimen, a veterinarian or veterinary technician should demonstrate the proper technique. In order to be effective, insulin must be properly handled with refrigeration and the gentle rolling of a vial to mix it.
Without proper treatment, a cat’s health and quality of life will begin to deteriorate over a period of days to weeks to months. For owners that decide not to pursue treatment, euthanasia is a humane option.
All About Insulin
There are several types of insulin used in the treatment of cats with diabetes mellitus. The characteristics differ as to the source, duration of action, concentration and the frequency of administration. Different types of insulin are not interchangeable, so once a cat is well-regulated with one type of insulin, it is not generally advised to change the type or brand being used.
Insulin preparations can be short-acting (regular insulin), intermediate-acting (Lente or NPH), or long-acting (glargine, Ultralente, protamine zinc insulin - PZI). Generally, insulins which are short- or intermediate-acting are given twice daily, whereas long-acting insulins may need to be given once or twice a day, depending upon the individual cat’s response. The number of units of insulin your cat receives depends upon the type of insulin used, and your cat's response.
Insulin is available in concentrations of 40 units/milliliter (U/ml), 100 U/ml, and 500 U/ml. There are corresponding syringes to use for the measurement of the three concentrations of insulin. For example, if you are using insulin with 40 U/ml, you must measure and administer it with a U-40 syringe. Using a U-100 or U-500 syringe would result in an incorrect dosage, potentially resulting in a fatal outcome. Always verify that you have the correct syringes to correspond with your cat’s type of insulin and address any concerns with your veterinarian.
In general, long-acting insulins are most appropriate for cats. Glargine insulin is a human recombinant insulin that results in a continual release of small amounts of insulin. This keeps the blood glucose level far more stable. Glargine is often considered to be superior to PZI or lente insulins in newly-diagnosed diabetic cats. In some cats, it can even result in remission when used in combination with a low-carbohydrate-high-protein diet. For those cats that have been on long term therapy with other insulins, the chance of going into remission is less likely.
At Home Treatment of Diabetes
While diabetic cats need frequent veterinary visits for monitoring, their day to day treatment and monitoring happens at home. Insulin should be kept in the refrigerator. Prior to administering a dose, gently roll the vial between your hands. Insulin should not be vigorously shaken, as this can make the molecules ineffective.
When administering insulin, keep a record of each insulin dose given. It is best to have one family member responsible for administration, so missed doses and double doses do not occur as a result of miscommunication. Remember, if a cat receives only a partial dose of insulin, do not give another dose. Wait until the next scheduled dose.
Diet is another important aspect of diabetic management in cats. Rather than free feeding, meals should be offered twice daily. It is generally preferable to feed a prescription diet, but certain over the counter diets can be acceptable for some cats, if fed consistently and recommended by a veterinarian. Monitor their appetite and food consumption, as changes may impact the insulin dose needed.
Monitoring Diabetic Cats at Home
Diabetic cats require a considerable amount of monitoring with respect to their signs and symptoms, as well as blood testing. Since stress can result in false elevations in a cat’s blood glucose, performing a blood glucose curve in a relaxed home environment can provide more accurate results. Based on an individual cat’s temperament and owner’s desire to do so, a veterinarian may discuss using an instrument called a glucometer to measure a cat’s blood glucose at home. Insulin requirements often change over time and the dose of insulin may need periodic adjustments based upon blood glucose monitoring.
On a day to day basis, cats should be monitored for their overall attitude, water consumption, frequency and amount of urination, appetite and signs of hypoglycemia (low blood glucose). These are all clues as to how well a cat is responding to therapy. This information is very valuable in evaluating a cat's progress. Signs that the blood glucose is too low include lethargy, depression, weakness, seizures and coma. Should you see any of these signs, immediately apply corn syrup to your cat’s gums and contact your veterinarian.
Overweight cats should lose weight at a gradual pace, allowing them to achieve a healthy body weight. As a cat's weight changes, their insulin requirements may also change. Monitoring a cat’s body weight is an excellent way to monitor the success of insulin therapy.
Diabetic cats should be kept indoors or under very close supervision while outside. Outdoor cats are at much greater risk of missing their scheduled insulin injections and feeding times. While unsupervised outdoors, cat owners are unable to accurately monitor food intake, water consumption, urination or signs of hypoglycemia. For cats accustomed to going outside, many will learn to walk on a leash or be content to go outside on a harness and long lead while you are in the yard with them.
Depending on a cat's overall health, weight, difficulty in regulation or other factors, a veterinarian may also recommend measuring water intake or urine glucose (measured using paper strips and watching for a color change). Insulin dosages, however, should not be changed based solely on urine glucose levels. A urine glucose test is an average of the glucose level in the urine since the cat last urinated, which that could be many hours ago.
It is extremely important that owners of diabetic cats keep all of the appointments for exams and blood tests that a veterinarian recommends. The time of day that these appointments are scheduled is often critical. Owners should be sure to communicate any concerns or observations to the veterinarian. Working as a team greatly increases the probability of successfully regulating a diabetic cat. Remember to be patient. Regulating a cat with diabetes is much more difficult than regulating a dog or a person.
Insulin Resistance
Insulin resistance is said to occur when the blood glucose level of a cat cannot be regulated with an insulin dosage lower than two units per pound of body weight per day. There are many causes of insulin resistance and 'apparent' insulin resistance. Causes of 'apparent' insulin resistance include:
• Improper insulin administration: Inadequate mixing of insulin, improper measurement of the dose (misreading the syringe, using the wrong type of syringe) and errors in injecting the insulin can result in the cat not receiving the proper dose of insulin. If insulin resistance is suspected, this is the first area to review. • Inactive insulin: If insulin is improperly stored, used after the expiration date has lapsed, has been vigorously shaken or exposed to higher temperatures, it may lose its potency. The easiest way to determine if inactive insulin is the problem is to use a new bottle of insulin. • Somogyi effect: The Somogyi effect, also called insulin-induced hyperglycemia or rebound hyperglycemia, is somewhat difficult to understand. Essentially, if too much insulin is given, the blood glucose level goes so low that it stimulates the production of other hormones in the body, such as epinephrine. This promotes the breakdown of glycogen (the chemical compound which the body uses to store glucose) and increases the blood glucose level above normal. • Changes in food or feeding schedule: If the feeding schedule, type of food or access to food has changed, apparent insulin resistance could occur.
If the above causes of an inadequate response to insulin have been eliminated, true insulin resistance may be occurring. It is sometimes difficult to determine the cause and it may require multiple laboratory tests to make the determination. Causes of true insulin-resistant states include:
• Interference by medications: The long term administration of glucocorticoids, such as dexamethasone, methylprednisolone (e.g. Depo-Medrol) or prednisolone, can result in the onset of diabetes mellitus and insulin resistance. • Poor absorption of insulin: Even when active insulin is administered correctly, some cats do not absorb insulin well from the site of injection under the skin. These cats generally respond well to insulin given intravenously or intramuscularly, but this should only be performed under a veterinarian’s guidance. • Concurrent diseases: Infections, diabetic ketoacidosis, pancreatitis, hepatic lipidosis, kidney disease or hormonal disorders, such as Cushing's disease, hyperthyroidism or acromegaly can affect the metabolism and effectiveness of insulin in the body. Many of these diseases change the levels of other hormones in the body, which ultimately affect the glucose level. • Obesity: In humans, obesity is more commonly related to insulin resistance. It has been suggested that obesity in cats can also result in insulin resistance. It is known that as obese cats lose weight, their need for insulin therapy decreases and is sometimes eliminated. • Production of antibodies against insulin: Insulin and other components added during the manufacture of injectable insulin can be considered 'foreign' by the body and cause the body to produce antibodies to destroy them. This is generally quite rare and is more likely to occur in cats if pork or human recombinant insulin are used.
There are many combinations of insulin types, dosages and frequencies of administration to be considered when attempting to regulate a cat with diabetes. The successful regulation of a diabetic cat is determined by the results of a blood glucose curve and the response of the cat, including their appetite, attitude, water consumption and urine production. The ongoing monitoring and treatment of a diabetic cat is a major commitment, but can be accomplished with the dedication of the pet owner and veterinarian.