This handout provides detailed information on the principles of treatment for diabetes mellitus. For more information about diabetes mellitus and its treatment, see the handouts "Diabetes Mellitus in Cats: Overview" and "Diabetes Mellitus: Insulin Treatment in Cats."
What is diabetes mellitus?
Diabetes mellitus is caused by the failure of the pancreas to regulate blood sugar (glucose). Insulin regulates the level of glucose in the bloodstream and controls the delivery of glucose to the tissues of the body. The clinical signs of diabetes mellitus are related to elevated concentrations of blood glucose and the inability of the body to use glucose as an energy source.
In cats, diabetes mellitus is most often type II diabetes, meaning insulin is still being produced, but there isn’t enough, or the cells don’t respond to it appropriately (insulin resistance). This type of diabetes usually results from obesity, creating insulin resistance. Although most cats need insulin to stabilize their blood sugar, some cats lose their requirement for insulin if they are able to achieve a normal body weight.
Some people with diabetes take insulin shots and others take oral medication. Is this true for cats?
In humans, there are two types of diabetes mellitus. Both types are similar in that there is a failure to regulate blood sugar, but the basic mechanisms of the disease differ.
Type I diabetes mellitus (sometimes called insulin-dependent diabetes mellitus) results from total or near-complete destruction of the pancreatic beta-cells. This type isn’t as common in cats as it is in dogs, but can occur. As the name implies, cats with this type of diabetes require insulin injections to stabilize blood sugar.
Type II diabetes mellitus (non-insulin-dependent diabetes mellitus) is different because some insulin-producing cells remain. However, the amount of insulin produced is insufficient, or there is a delayed response in secreting it, or the tissues of the cat's body are relatively resistant to it (also referred to as insulin resistance). Cats with this form of diabetes may be treated with oral medication that triggers increased loss of glucose into the urine, resulting in normal blood glucose levels. However, not all cats with diabetes respond well to these treatments and may ultimately require insulin.
How is diabetes mellitus treated in cats? Is treatment expensive?
Your veterinarian will discuss the best treatment for your cat based on their condition and test results. Cats that receive oral medication are often monitored very closely initially, with recheck examinations and lab testing to ensure they are good candidates for the treatment.
Cats with insulin-dependent diabetes mellitus require one or more daily insulin injections. Although a cat can go a day or so without insulin and typically not have a crisis, this should not happen regularly. Treatment should be looked upon as part of your cat’s daily routine. This means that you, as the cat's owner, must make a financial and personal commitment to treat your cat. If you are out of town or go on vacation, your cat must receive proper treatment in your absence.
Costs of treatment can vary depending on how quickly your cat’s glucose is regulated with insulin and if there are any other underlying conditions contributing to diabetes. Many cats also benefit from some sort of dietary change. Your veterinarian may recommend a special diabetic formulation and possibly a change in their feeding schedule.
Initially, if your cat is ill, they may be hospitalized for a few days to deal with any immediate crisis and to begin the insulin regulation process. The "immediate crisis" is significant if your cat is so sick it has quit eating and drinking for several days and has abnormal blood and urine test results. Cats in this state, called diabetic ketoacidosis, may require several days of intensive care.
"It may take a month or more to achieve good insulin regulation."
Regular return visits may be required at intervals recommended by your veterinarian to monitor your cat’s progress and response to insulin. Your vet may recommend assessing your cat’s progress at home using home glucose curves or a continuous glucose monitor (usually applied at the clinic). It may take a month or more to achieve good insulin regulation.
Your financial commitment may be significant if complications arise during the initial regulation process or if regulation is complicated. Your veterinarian will work with you to try to achieve consistent regulation, but some cats are difficult to regulate and keep regulated. It is important that you pay close attention to all instructions related to administration of medication, diet, and home monitoring. One serious complication that can arise is hypoglycemia, or low blood sugar, which can be fatal. This may occur due to inconsistencies in treatment.
What specifically is the treatment of diabetes?
If your cat is feeling well, your veterinarian may recommend oral treatment. New medications have been approved to help regulate blood glucose levels in cats, including once-daily oral medications bexagliflozin (Bexacat®) and velagliflozin (Senvelgo®). These medications regulate blood glucose by getting the kidneys to release more glucose into the urine, causing blood sugar levels to fall to normal levels. Good candidates for this treatment are cats in the early stage of diabetes, who can likely still produce insulin. See handout “Diabetes Mellitus: Oral Treatments for Cats” for more information.
Most often, the treatment for many diabetic cats is insulin injections. Many people are initially fearful of inflicting pain or harm by giving insulin injections. Fortunately, this fear is unfounded. Modern, disposable insulin injection needles are extremely sharp and cause minimal pain; newer formulations of insulin do not sting or otherwise hurt on injection; and the injections are given just underneath the skin in areas where it is impossible to damage internal structures. Specific details about the use and storage of insulin are provided in the handout: "Diabetes Mellitus: Insulin Treatment in Cats."
"Your veterinary team will carefully review your cat’s specific treatment and offer advice on how to best administer insulin injections."
Although insulin injection may at first seem complicated and somewhat overwhelming, the procedure will quickly become second nature. Your veterinary team will carefully review your cat’s specific treatment and offer advice on how to best administer insulin injections.
What your cat eats can be important in the management of diabetes mellitus. Cats with diabetes are often prescribed a diet specific to their needs. This diet may promote weight loss for an overweight cat or prioritize protein and calorie density in a cat that is underweight. There is no best diet for diabetic cats. Your veterinarian will discuss specific diet recommendations for your cat's needs.
Your cat's feeding routine may also be important. Some owners feed their cats by always leaving food in the bowl, so that the cat can eat whenever it wants (called free-choice feeding). When feeding this way, you must find a way to accurately measure the amount of food that is consumed in a 24-hour period. This may work for some diabetic cats; however, your veterinarian may recommend switching to meal feeding if your cat is being treated with insulin. The preferred way is to feed twice daily, just before each insulin injection.
"Consistent treatment is a vital component of proper management of a diabetic cat."
Consistent treatment is a vital component of proper management of a diabetic cat. Your cat needs consistent administration of insulin or prescribed oral medication, consistent feeding, and a stable, stress-free lifestyle. Although it is not essential, your cat should live indoors to minimize uncontrollable variables that can disrupt regulation.
How often do diabetic cats need to be monitored?
Your cat's progress must be checked on a regular basis. Monitoring is a joint project that owners and veterinarians must work on together. Most cats require more frequent monitoring initially, regardless of treatment. After your cat’s condition is stabilized, and you are comfortable with the prescribed treatment and diet, blood and urine testing will typically be performed every one to three months.
What is involved in home monitoring?
You may be involved in several types of monitoring. You need to be constantly aware of your cat's appetite, weight, water consumption, and urine output.
- You should feed a consistent amount of food each day, which allows you to be aware of changes in consumption.
- You should weigh your cat at least monthly and notify your veterinarian if there is any weight loss. It is best to use the same scales each time. It is also important to be aware of their muscle condition. Your veterinary team can show you how to assess this.
- You should develop a way to measure water consumption. Keeping a record of your cat's water consumption for a few weeks will allow you to establish what is normal for your cat. Measure the quantity of water you put in their bowls in the morning and measure how much is left about 24 hours later. You can also estimate whether your cat's drinking is normal by counting the number of times it drinks each day. When properly regulated, your cat should drink no more than six times per day. If they exceed this, take an accurate measurement.
Any significant change in your cat's food intake, weight, water intake, or urine output may be an indicator that the diabetes is not well controlled. If you observe changes, schedule an appointment with your veterinarian for blood testing.
If your cat is on oral treatment, your veterinarian may recommend monitoring ketones in their urine. This monitoring can help catch signs of impending diabetic ketoacidosis before your cat becomes sick, allowing appropriate treatment to be initiated. Your veterinarian will recommend what strips to apply in the litter box, or may recommend testing in clinic. Your vet may recommend you test your cat for glucose in the urine. This monitoring can be valuable in cases where there is concern for hypoglycemia, as no glucose in the urine often indicates hypoglycemia.
"Any significant change in your cat's food intake, weight, water intake, or urine output may be an indicator that the diabetes is not well controlled."
There are several ways to detect glucose in urine. You may purchase urine glucose test strips in any pharmacy. They are designed for use in humans with diabetes but can also work for cats. These strips can be placed in the litter box. Regardless of when you test the urine glucose, you must be consistent. If you can test in the morning, try to perform all tests in the morning. If no glucose is detected two mornings in a row, your vet should be notified, as there the insulin dose may need to be changed.
Some cats may also have their blood glucose monitored at home. For best results, this requires special veterinary (pet) blood glucose monitors (AlphaTrak 2™). Your veterinarian will recommend this type of monitoring if your cat is a suitable candidate. Not all pet parents or cats will allow, or enjoy, this type of monitoring that requires you to obtain small blood samples from your cat.
Another option for home monitoring is a continuous glucose monitor (FreeStyle Libre™) that is inserted into the skin and stays in place for up to 14 days. The sensor tracks glucose every minute and stores up to 8 hours of data. The owner passes a scanner or compatible cell phone over the device several times a day and this records glucose levels reflective of blood glucose. Ask your veterinarian if this is a good option for your cat.
How will my veterinarian monitor my cat's diabetes?
There are common blood tests for monitoring diabetes in your cat, including blood ketones, a blood glucose curve either from sequential blood sampling or a continuous glucose monitor, and fructosamine testing. New tests are also available that can aid your veterinarian in accurately monitoring your cat’s diabetes. One or more of these tests may be recommended at periodic intervals for monitoring, even if your cat appears well regulated.
Testing should also be done any time clinical signs of diabetes are present. Your veterinarian may recommend other testing, such as pancreatitis testing or urine cultures to check for infection.
The most common diabetes monitoring test, a blood glucose curve, involves monitoring the level of glucose in the blood over a 12–24-hour period. Blood glucose curves generally start around the time of insulin administration and continue until the next dose or, in some cases, for a full 24 hours. Blood samples may be collected every 1–2 hours during this time and will reflect how the pet is responding to insulin on that day.
The usual procedure for measuring a blood glucose curve is as follows:
- Feed your cat its normal morning meal and then bring your cat to the hospital immediately, before administering insulin. If you cannot get your cat to the hospital within 30 minutes, do not feed him and bring your cat's food with you. Also, be sure to bring your insulin to the veterinary hospital.
- A blood sample will be taken immediately to assess your cat's pre-insulin glucose level.
- The veterinarian will give your cat's dose of insulin and feed your cat if necessary.
- Blood samples will be taken every one to three hours throughout the day, generally for an eight- to ten-hour period or longer. This will allow your veterinarian to determine the peak insulin effect and how your pet responds to insulin over the course of the day. This is often referred to as an "insulin-response curve."
Some cats get too excited or nervous when riding in the car or being in the hospital, causing a false elevation in glucose readings. Your veterinarian may recommend admitting your cat to the hospital the morning (or afternoon) before testing so it can settle down for testing the next day. Alternatively, they may instruct you on how to perform a blood glucose curve at home or how you can use continuous glucose monitoring to assess your cat’s blood glucose regulation.
"Some cats get too excited or nervous when riding in the car or being in the hospital, causing a false elevation in glucose readings."
An alternative test is a fructosamine test. Fructosamine gives your veterinarian an approximate average of blood glucose levels for the last two weeks. Stress and inconsistencies in diet and exercise have less effect on this test than on the blood glucose test. If no glucose curve options work for your cat, this may be the preferred test. It does not require fasting and can be done at any time of day. It can also be useful if there is worry about hypoglycemia. Your veterinarian will discuss this test and if it is appropriate for your cat's monitoring program.
Does hypoglycemia occur in cats?
Hypoglycemia means low blood sugar. If the blood sugar falls below 54 mg/dl (3 mmol/L), it can be life-threatening. Hypoglycemia generally occurs under two conditions:
- When the prescribed insulin dose is too high. Although most cats may require the same dose of insulin for long periods of time, it is possible for a cat’s insulin needs to change. The most common causes for a sudden change are a reduction in food intake and an increase in exercise or activity. The cat should eat before giving the insulin injection, because once the insulin is administered, it can’t be removed from the body. If your cat does not eat, skip that dose of insulin. If only half of the food is eaten, give only a half dose of insulin. Always remember it is better in the short term for the blood sugar to be too high than too low. Ask your veterinarian for guidance on what to do if your pet fails to eat or eats only a portion of its food. These are only general guidelines and may vary in your cat.
- When too much insulin is given mistakenly. This can occur because the insulin was not properly measured in the syringe or because two doses were given. You may forget that you gave it and repeat the dose or two people in the family may each give a dose. A chart to record insulin administration will help to prevent your cat being treated twice.
Watch for any subtle signs of hypoglycemia. It is the first sign of impending problems. A cat is most likely to become hypoglycemic during peak insulin effect, which is generally 5 to 8 hours after an insulin injection. When blood glucose is only mildly low, your cat may act tired and unresponsive. You may call your cat and get little or no response. Your cat may stumble or appear unstable when walking. Within a few hours, the blood glucose will rise, and your cat will return to normal. Since many cats sleep a lot during the day, these important signs can easily be missed. If you see any signs of hypoglycemia, bring your cat in for blood glucose testing.
If your cat is slow to recover from this period of lethargy, you should give corn syrup by mouth (one tablespoon for every 20 pounds, or 15 mL/10 kg) or a commercially prepared diabetic sugar solution. Sugary syrups can be absorbed from the gums, so do not force them to the back of your cat’s mouth; doing so could risk them aspirating the solution into their lungs if they are unable to swallow properly. Contact your veterinarian immediately for further instructions. This can be an emergency.
If severe hypoglycemia occurs, a cat may have seizures or lose consciousness. Ultimately, untreated hypoglycemia will lead to coma and death. It is an emergency that can only be reversed with intravenous administration of glucose. If it occurs during office hours, take your cat to the veterinarian's office immediately. If it occurs at night or on the weekend, call your veterinarian's emergency phone number for instructions.
