What Is Diabetes Mellitus?

There are two forms of diabetes in cats: diabetes insipidus and diabetes mellitus. Diabetes insipidus is a very rare disorder that results in failure to regulate body water content. The more common type of diabetes is diabetes mellitus. This disease is seen by the doctors at the Animal Hospital at Thorndale on a fairly regular basis, usually in cats 5 years of age or older. We have even diagnosed this disease in a 2 year old, rather obese cat. While having a “chubby buddy” may seem cute, the overweight cat is at risk for many health problems, just as is the overweight human. That said, not all diabetic cats are obese. There is also an increased incidence in older cats. Diabetes mellitus can be difficult to regulate in our pets. Understanding the disease will help you learn how to help your cat.

Simply put, diabetes mellitus a failure of the pancreas to regulate blood sugar. The pancreas is a small but vital organ that is located near the stomach. It has two significant populations of cells. One group of cells produces the enzymes necessary for proper digestion. The other group, called beta cells, produces the hormone called insulin.

Types of Diabetes in Cats

In cats, two types of diabetes mellitus have been discovered. Both types are similar in that there is a failure to regulate blood sugar, but the basic mechanisms of disease differ somewhat between the two groups.

1. Type I, or Insulin Dependent Diabetes Mellitus, results from total or near-complete destruction of the beta cells. This is the most common type of feline diabetes. As the name implies, cats with this type of diabetes require insulin injections to stabilize blood sugar.
2. Type II, or Non-Insulin Dependent Diabetes Mellitus, is different because some insulin-producing cells remain. However, the amount produced is insufficient, there is a delayed response in secreting it, and the tissues of the cats body are relatively resistant to it. These cats potentially could be treated with an oral drug that stimulates the remaining functional cells to produce or release insulin in an adequate amount to normalize blood sugar. However, most achieve better control when treated with insulin. Cats with Type II diabetes may ultimately progress to total beta cell destruction and then require insulin injections.
3. Interestingly, with the use of newer forms of insulin, some cats seem to “recover” from their diabetes. These cats may continue to have good control with proper diet, generally a low carbohydrate prescription food.

What Insulin Does for the Body

The role of insulin is much like that of a gatekeeper. It stands at the surface of body cells and opens the door, allowing glucose to leave the blood stream and pass into the cells. Glucose is a vital substance that provides much of the energy needed for life, and it must work inside the cells. Without an adequate amount of insulin, glucose is unable to get into the cells. It accumulates in the blood, setting in motion a series of events that can ultimately prove fatal.

When insulin is deficient, the cells become starved for a source of energy. In response to this, the body starts breaking down stores of fat and protein to use as alternative energy sources. As a consequence, the cat eats more; thus, we have weight loss in a cat with a ravenous appetite. The body tries to eliminate the excess glucose by eliminating it in the urine. However, glucose (blood sugar) attracts water; thus, urine glucose takes with it large quantities of the body’s fluids, resulting in the production of a large amount of urine. To avoid dehydration, the cat drinks more and more water. Thus, we have the four classical signs of diabetes:

CLASSICAL SIGNS OF DIABETES MELLITUS IN CATS:

1. Weight loss
2. Ravenous appetite
3. Increased water consumption – this is very important because normal cats do not drink much water
4. Increased urination – often seen as larger clumps in the cat litter.

Over time, an untreated diabetic cat will become very ill. Some of these cats no longer eat, may appear wobbly on their feet and don’t always drink as much water as they need to replace their losses.

Diagnosing Diabetes

The diagnosis of diabetes mellitus is based on three criteria: the four classical clinical signs, the presence of a persistently high level of glucose in the blood stream, and the presence of glucose in the urine.

The normal level of glucose in the blood is 80-120 mg/dl. It may rise to 250-300 mg/dl following a meal or when the cat is very excited. However, diabetes is the only common disease that will cause the blood glucose level to rise above 400 mg/dl. Some diabetic cats will have a glucose level as high as 800 mg/dl, although most will be in the range of 400-600 mg/dl.

To keep the body from losing its needed glucose, the kidneys do not allow glucose to be filtered out of the blood stream until an excessive level is reached. This means that cats with a normal blood glucose level will not have glucose in the urine. Diabetic cats, however, have excessive amounts of glucose in the blood, so it will be present in the urine.

The diagnosis of diabetes seems rather simple, and in most cats it is. However, some diabetic cats do not meet all the criteria. For these, another test is performed called fructosamine. This test represents the average blood glucose level for the past two weeks. It minimizes the influence that stress and eating have on blood glucose levels and can be very helpful in understanding difficult cases.

What It Means for Your Cat to be Diabetic

For the diabetic cat, one reality exists. Blood glucose cannot be normalized without treatment. Although the cat can go a few days without treatment and not get into a crisis, treatment should be looked upon as part of the cat’s daily routine. Treatment almost always requires some dietary changes. Whether an individual cat will require insulin injections will vary.

As for the owner, there are two implications: financial commitment and personal commitment.

When your cat is well regulated, the maintenance costs are minimal. The special diet, insulin, and syringes are not expensive. However, the financial commitment can be significant during the initial regulation process and if complications arise.

In some cases, your cat will be hospitalized for a few days to deal with the immediate crisis and to begin the regulation process. The “immediate crisis” is only great if your cat is so sick that it has quit eating and drinking for several days. Cats in this state, called ketoacidosis, may require a week or more of hospitalization with quite a bit of laboratory testing. Otherwise, the initial hospitalization may be only for a day or two to get some testing done and to begin treatment. At that point, your cat goes home for you to administer medication. At first, return visits are required every 5-7 days to monitor progress. It may take a month or more to achieve good regulation.

The financial commitment may again be significant if complications arise. We will work with you to achieve consistent regulation, but some cats are difficult to keep regulated. It is important that you pay close attention to our instructions related to administration of medication, to diet, and to home monitoring. Consistency is the key to prolonged regulation. The more you keep the medication, diet, and activity the same from one day to the next, the easier it will be to keep your cat regulated.

Another complication that can arise is hypoglycemia or low blood sugar; if severe, it may be fatal. This may occur due to inconsistencies in treatment or because some cats can have a spontaneous remission of their disease. This will be explained in subsequent paragraphs.

Your personal commitment to treating this cat is very important in maintaining regulation and preventing crises. Most diabetic cats require insulin injections twice daily, at about 12 hour intervals. They must be fed the same food in the same amount on the same schedule every day. If you are out of town, your cat must receive proper treatment while you are gone. These factors should be considered carefully.

Treatment

As mentioned, the key to successful treatment is consistency. Your cat needs consistent administration of medication, consistent feeding, and a stable, stress-free lifestyle. To best achieve this, it is preferred that your cat lives indoors. Although that is not essential, indoor living removes many uncontrollable variables that can disrupt regulation.

The first step in treatment is to alter your cat’s diet. Diets that are low in carbohydrate and higher in protein are sometimes all that will be needed, especially if the cat is remission (recovered) from its diabetes. This means that the cat does not have to process a large amount of sugar at one time. If your cat is overweight, measuring this food to use is as a reducing-type diet is fed until the proper weight is achieved. This is sort of like an Atkins, or “Catkins”, if you will, approach to metabolic control and can be very helpful.

Your cat’s feeding routine is also important. The average cat prefers to eat about 10-15 times per day, one mouthful at a time. This means that food is left in the bowl at all times for free choice feeding. Fortunately, this is an OK way to feed a diabetic cat. However, it is also desirable to monitor how much food is eaten each day. Twice daily feedings are therefore also helpful. Feeding the diabetic food to your other cats is not harmful unless they have problems with kidney function, then it must be avoided. We realize that if you have more than one cat, this may be difficult, but please make an effort, as this is part of the home monitoring that should occur.

The second step in treatment is to use a drug to control (lower) control blood glucose levels. The first choice is to give insulin injections. Rarely will cats do well with the oral medications.

Insulin injections are usually the first choice because this approach is to replace the hormone that is missing or made in inadequate amounts. Although many people are initially uncomfortable with the thought of giving injections, for most cats, insulin injections are easier than giving tablets for reasons described below.

This is generally our preferred way to treat diabetic cats.

Many people are initially fearful of giving insulin injections. If this is your initial reaction, consider these points.

1. 1) Insulin does not cause pain when it is injected.
2. 2) The injections are made with very tiny needles that your cat hardly feels.
3. 3) The injections are given just under the skin in areas in which it is almost impossible to cause damage to any vital organ. Please do not decide whether to treat your cat with insulin until we have demonstrated the injection technique. You will be pleasantly surprised at how easy it is.

Insulin Therapy and Administration

About Insulin

Insulin comes in an airtight bottle that is labeled with the insulin type and the concentration. Before using, mix the contents. It says on the label to roll it gently, not shake it. The reason for this is to prevent foam formation, which will make accurate measuring difficult. Some of the types of insulin used in cats settle out of suspension in a few hours. If it is not carefully mixed, then dosing will not be accurate. Therefore, the trick is to roll it vigorously between your hands enough to mix it without creating foam. Since bubbles can be removed (as described later), it is more important to mix it well than to worry too much about foam formation.

Insulin is a hormone that will lose its effectiveness if exposed to direct sunlight or high temperatures. It should be kept in the refrigerator, but it should not be frozen. Insulin is safe as long as it is used as directed, but it should be kept out of reach of children.

Several types of insulin are used in cats. Some are made for use in humans and obtained from regular pharmacies. Insulins made for humans have a concentration of 100 units per milliliter and are called U100 insulins. Protamine zinc insulin (PZI) is made specifically for cats and obtained from veterinarians. PZI has a concentration of 40 units of active insulin crystals per milliliter of fluid. Thus it is called U40 insulin. This is important to know because there are two types of insulin syringes, U40 syringes and U100 syringes. They are made to be used with their respective types of insulin and must not be interchanged or improper dosing will occur. Most cats can do very well, and often go into remission when using the human glargine U100 (Lantus) insulin. Generally we recommend beginning cats with this insulin. While it may seem that cats would be better controlled with a PZI insulin, that is not always the case. Also, veterinary insulin products have had a history of disappearing from availability, leaving cat owners in need of switching to the human products anyway.

Drawing up Insulin

Have the syringe and needle, insulin bottle, and cat ready. Then, follow these steps:

1. Remove the guard from the needle, and draw back the plunger to the appropriate dose level.
2. Carefully insert the needle into the insulin bottle.
3. Inject air into the bottle; this prevents a vacuum from forming within the bottle by replacing the volume you are drawing out.
4. Withdraw the correct amount of insulin into the syringe. To do this, it is best to overfill the syringe and then inject the excess back into the bottle. When doing this, hold the bottle and syringe vertically with the needle stuck into the bottle, the bottle upside down with the syringe below it. If you rest this against your hand, your can tap any bubbles loose from the syringe. They will rise toward the bottle and you can inject them back into the bottle with the excess insulin. Our office will be happy to demonstrate this technique.

Before injecting your cat with the insulin, verify that there are no air bubbles in the syringe. If you get an air bubble, and cannot accomplish step #4 above, you can draw twice as much insulin into the syringe as you need. Then withdraw the needle from the insulin bottle and tap the barrel of the syringe with your finger to make the air bubble rise to the nozzle of the syringe. Gently and slowly expel the air bubble by moving the plunger upward. This way you are discarding the excess insulin along with the air bubble.

When this has been done, check that you have the correct amount of insulin in the syringe. The correct dose of insulin can be assured if you measure from the needle end, or “0” on the syringe barrel, to the end of the plunger nearest the needle. Be certain you are reading your syringe correctly. Cats are small and usually only need 1-3 units of insulin. We will be certain to prescribe the easiest size of the U100 syringes for you and demonstrate how to read the correct dose on the syringe.

Injecting Insulin

The steps to follow for injecting insulin are:

1. Hold the syringe in your right hand (switch hands if you are left-handed).
2. Have someone hold your cat while you pick up a fold of skin from somewhere along your cat’s back with your free hand (pick up a different spot each day). If you are alone, you can kneel on the floor with the cat wedged between your legs. Covering the front of the cat with a towel my calm him.
3. Quickly push the very sharp, very thin needle through your cat’s skin. This should be easy and painless. However, take care to push the needle through only one layer of skin and not into your finger or through two layers of skin back outside agaain. The latter will result in injecting the insulin onto your cat’s hair coat or onto the floor. The needle should be directed parallel to the backbone or angled slightly downward.
4. To inject the insulin, place your thumb on the plunger and push it all the way into the syringe barrel.
5. Withdraw the needle from your cat’s skin. Immediately place the needle guard over the needle and discard the needle and syringe.
6. Stroke your cat to reward it for sitting quietly.
7. Be aware that some communities have strict rules about disposal of medical waste material so don’t throw the needle/syringe into the trash until you know if this is permissible. If it is not, we can dispose of them for you. Keep used needles in a sealed coffee tin out of the reach of children

It is neither necessary nor desirable to swab the skin with alcohol to “sterilize” it. There are four reasons:

1. Due to the nature of the thick hair coat and the type of bacteria that live near the skin of cats, brief swabbing with alcohol or any other antiseptic does not really kill all the bacteria.
2. Because a small amount of alcohol can be carried through the skin by the needle, it may actually carry bacteria with it into the skin
3. The sting caused by the alcohol can make your cat dislike the injections.
4. If you have accidentally injected the insulin on the surface of the skin, you will not know it. If you do not use alcohol and the skin or hair is wet following an injection, the injection was not done properly.

Although the above procedures may at first seem complicated and somewhat overwhelming, they will very quickly become second nature. Your cat will soon learn that once or twice each day it has to sit still for a few minutes. In most cases, a reward of stroking results in a fully cooperative cat that eventually may not even need to be held.

Monitoring

It is necessary that your cat’s progress be checked on a regular basis. Monitoring is a joint project on which owners and veterinarians must work together.

Home Monitoring

Your part can be performed in several ways.

The first way is to monitor your cat for signs of diabetes. To do this, you need to be constantly aware of your cat’s appetite, weight, water consumption, and urine output. You should be feeding a constant amount of food each day, which will allow you to be aware of days that your cat does not eat all of it or is unusually hungry after the feeding. You should weigh your cat at least twice monthly. It is best to use the same scales each time. A baby scale works well for this. If you have several cats that eat together and use the same litter box, monitoring weight is the best because it is specific to this one cat.

If possible, you should develop a way to measure water consumption. The average 10 pound (4.5 kg) cat should drink no more than 7 1/2 oz. (225 ml) of water per 24 hours. Since this is highly variable from one cat to another, keeping a record of your cat’s water consumption for a few weeks will allow you to establish what is normal for your cat. Another way to measure water consumption is based on the number of times it drinks each day. When properly regulated, it should drink no more than four times per day. If this is exceeded, you should take steps to make an actual measurement.

Urine output can be measured by determining the amount of litter that is scooped out of the litter box. This is a little less accurate if you have more than one cat that uses the litter box, but it can still be meaningful. The best way to measure litter is to use a clumping litter and scoop it into a sealable container. After a few weeks you will be able to know the normal rate at which the jar fills. Too rapid filling will indicate that your cat’s urine production has increased.

Any significant change in your cat’s food intake, weight, water intake, or urine output is an indicator that the diabetes is not well controlled. We should see the cat at that time for blood testing.

The second method of home monitoring is to determine the presence of glucose in the urine. If your cat is properly regulated, there should be little to no glucose present in the urine. Keep in mind that this test may not always be accurate. It should never be used as a sole indication to increase the dose of insulin. Urine accumulates in the bladder over time, between trips to the litter box. A single urine sample only gives a general average of the amount of sugar filtering into the urine over that entire period of time between urinations. As such, if at some point during between urinations the blood sugar drops dangerously low, and then rebounds to a higher level, this averaging effect may tell you the cat is well controlled or suggests you need a higher insulin dose. On the contrary, increasing his dose could be fatal. Urine glucose is useful to detect trends and tell you when your cat needs blood sugar levels checked. No sugar in the urine may mean your cat is very well controlled or perhaps is in remission. Blood sugars need to be checked. Consistently very high urine sugar may mean the control is poor and the dose needs adjusting or a different type of insulin, with a different blood sugar profile needs to be tried.

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 they will also work in the cat. The use of special non-absorbing kitty litter permits you to dip the test strip into urine in the litter box. Aquarium gravel, Styrofoam packing “peanuts,” and commercial non-absorbing litter can be used. Since these are not ideal litter materials, they are best used on a periodic basis.

The third method is to learn how to measure your cats blood sugar levels at home. There are “Glucometers” designed for pet use. Blood samples can be obtained from the ear or foot pad with a special stylet. This is not particularly difficult to learn to do and has a number of advantages:

You may be able to perform a glucose curve at home when we have made adjustments to the dose. This will save you the expense of us doing the curve, and may actually give a more accurate refection of your cat’s response to the insulin dose. Stressors, such as coming into the hospital can cause even a normal cat’s blood sugars to elevate. Your cat could stay at home comfortably while you obtained the blood values.

Spot checks on blood sugar can be done at home. This is very important if you think you cat may have been overdosed or no longer needs his insulin (in remission). Of course, overdosing and other problems often require a visit to the veterinarian, but you can be talked through some emergency care (giving Kayo syrup for example) before bringing your cat to the hospital. Consistently high values may indicate a change in dose is needed, after another glucose curve is done.

Monitoring of Blood Glucose

Spot Checking the Blood Sugar Levels

Once we have established a Glucose Curve for your cat, we will know how long after insulin is given that it has its peak effect. This will be the lowest blood sugar through the day. This value is important because we do not want it to dip too low (see hypoglycemia below). Often this low point is about 6 hours after you give the insulin. We would like to see this value read about 100. Ideally, we would also like to measure a blood sugar right before the insulin is given, because this is the high blood sugar point, when there is little to no insulin left in the system.

Because hypoglycemia (too low blood sugar) is generally much more serious than hyperglycemia (too high blood sugar), the peak effect of the insulin is more critical. If the blood sugar levels are still very high at the time of day when the insulin should have pushed them to their lowest levels, we may need to adjust the dose you are using and repeat the full glucose curve to determine how your cat is responding to the insulin through the day.

The Glucose Curve

Determining the level of glucose in the blood is the most accurate means of monitoring. Glucose curves will be done initially to determine the proper dose and schedule for your cat. Then the glucose curve should be done about every 6 months if your cat seems to be well regulated. It should also be done at any time the clinical signs of diabetes return.

Timing is important when the blood glucose is determined. Eating will elevate the blood sugar for several hours.

Feed your cat its normal morning meal then bring it and your insulin to hospital. While it is best for us to given the insulin in the hospital the day of the glucose curve that is not always possible. If you typically give the insulin and feed your cat extremely early in the morning, we will likely ask you to keep to you regular schedule and feed and give the insulin at home.

Otherwise bring your cat, some food, and the insulin in the morning. If he has a favorite blanket or bed that may help keep him calm and comfortable.

For the curve, a blood sample will be taken immediately upon arrival, then we will give insulin and feed your cat if it did not eat at home. We continue to test his blood sugar levels every two hours to determine when there has been a peak insulin effect and how low the blood sugar levels go. Based on this information, we can determine whether we need to adjust the type of insulin or dosage.

If your cat gets excited or very nervous when riding in the car or being in the hospital, the glucose readings may be falsely elevated. We always take that into account when prescribing insulin.

Fructosamine Levels

This test is useful in monitoring “borderline” diabetic cats and when glucose curves are not practical due to the cat’s stress levels. We also use fructosamine levels to monitor cats that seem to be well controlled at home. In a single blood test, frustosamine gives a reasonable measure of the level of control of diabetes for 2 week’s to a month’s worth of time. Cats do not need to stay in the hospital for this test, and the timing for the blood sample during the day is not a problem.

Hypoglycemia is extremely dangerous!

Hypoglycemia means low blood sugar. If it is below 40 mg/dl, it can be life-threatening. Hypoglycemia occurs under three conditions:

1) If the insulin dose is too high. Although most cats will require the same dose of insulin for long periods of time, it is possible for the cat’s insulin requirements to change. However, the most common causes for change are a reduction in food intake and an increase in exercise or activity. The reason for feeding before the insulin injection is so you can know when the appetite changes. If your cat does not eat, skip that dose of insulin. If only half of the food is eaten just give a half dose of insulin. Always remember that it is better for the blood sugar to be too high than too low.

2) If too much insulin is given. 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 it, or two people in the family may each give a dose. A chart to record insulin administration will help to prevent the cat being treated twice.

3) If your cat has a spontaneous remission of the diabetes. This is a poorly understood phenomenon, but it definitely occurs in about 20% of diabetic cats. They can be diabetic and on treatment for many months, then suddenly no longer be diabetic. Since this is not predictable and happens quite suddenly, a hypoglycemic crisis (“insulin shock”) is sometimes the first indication.

The most likely time that a cat will become hypoglycemic is the time of peak insulin effect (5-8 hours after an insulin injection). When the blood glucose is only mildly low, the cat will be very tired and unresponsive. You may call your cat and get no response. 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, this important sign is easily missed. Watch for it; it is the first sign of impending problems. If you see it, please bring in your cat for blood testing. This is an important time for monitoring blood sugars at home. You can easily distinguish if your cat is just sleeping or is hypoglycemic.

If your cat is slow to recover from this period of lethargy, you should give it corn syrup (1 tablespoon by mouth) or feed one packet of a semi-moist cat food. If there is no response in 15 minutes, repeat the corn syrup or the semi-moist food. If there is still no response, contact us immediately for further instructions. (Note: Diabetic cats should not be fed semi-moist foods except for this situation. They tend to have a high sugar content.)

If severe hypoglycemia occurs, a cat will have seizures or lose consciousness. This is an emergency that can only be reversed with intravenous administration of glucose. If it occurs during office hours, come in immediately. If it occurs at night or on the weekend, call our emergency phone number for instructions.

Spontaneous Remission

This is a poorly understood phenomenon that only happens in a few cats. Unfortunately, it can happen rather suddenly so a hypoglycemic crisis may be created when the normal amount of insulin is given. When it occurs, the cat may be normal for a few weeks or for many months. Some of these cats can remain in remission for longer times if they have shed their excessive weight and are eating a low carbohydrate prescription diet.

SUMMARY OF INSTRUCTIONS FOR CATS RECEIVING INSULIN INJECTIONS

Read and reread this material so that you understand the specifics of proper regulation and how to recognize and treat hypoglycemia.

Get the supplies for treatment. Your prescription will specify the type of insulin and syringes. If you wish to use urine glucose tests strips, they should be purchased at a pharmacy.

Schedule an appointment so we can demonstrate how to properly mix, draw up and administer the insulin. It is best if you bring your cat to this appointment so you can both practice under a watchful, encouraging trained eye. Our goal is to have you be comfortable giving injections before you leave our hospital. We will practice with sterile saline injections (not insulin).

We may direct you to return the next day for either a spot blood sugar check or a full glucose curve. Generally the curve will need to be run around the seventh day of treatment.

Return for a glucose curve, no later than 8:00 a.m., on your scheduled day. Feed your cat that morning and immediately bring it to the hospital. Do not give insulin, but bring it with you. (If you are dosing at unusual hours because of your life schedule, let us know and we will instruct you on whether to give the insulin at home.

Based on the results of the glucose curve, we will discuss and schedule further testing.