What is diabetes mellitus?

Diabetes mellitus is an uncommon disease in cats, but is seen more frequently in middle to old-age cats and more common in males than females. Brown Burmese cats are more commonly affected than other breeds.  Diabetes mellitus arises from 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 insulin. 

Why is insulin so important?

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 inside 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 in unable to get into the cells. It accumulates in the blood, setting in motion a series of events which 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 excreting it in the urine. High levels of glucose in the urine also draws more water into the urine resulting in the production of a large amount of urine. To avoid dehydration, the cat drinks more and more water.

CLASSICAL SIGNS OF DIABETES MELLITUS

The most common clinical signs seen in diabetic patients are an increase in the volume of urine that is produced and, to compensate for this, an increase in the amount of water that is drunk. Weight loss is also a common feature, and an increase in appetite may be noticed in some cats. Recognition of these signs is variable though, particularly because of the life-style of some cats. If a cat spends a lot of time outdoors for example, it may drink from ponds or pools of water outside rather than appearing to drink excessively from what is provided indoors.

How is diabetes mellitus diagnosed?

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

To prevent glucose loss from the body the kidneys only allow it to pass out in the urine when very high levels of glucose are circulating in the blood. 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.

What are the implications for me and my cat?

Treatment should be looked upon as part of the cat's daily routine. Treatment almost always requires administration of insulin and some modification of the diet.

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 very expensive. However, the financial commitment is significant during the initial stabilisation process and if complications arise.

What is involved in treatment?

Initial steps in treating a diabetic cat may involve removal of any predisposing causes for the diabetes. For example, the administration of some drugs predisposes cats to develop diabetes, and withdrawal of these drugs may lead to resolution of the condition. Also obese cats are more prone to develop diabetes and again, reduction in bodyweight can lead to resolution of the signs in some of these individuals.

If there are no predisposing causes, or if correction of the predisposing causes does not lead to resolution of the diabetes, specific treatment is required. Although a small proportion of cats will respond to a form of tablet (‘oral hypoglycaemic’) designed to increase the amount of insulin produced by the pancreas and increase its effectiveness, most cats will require insulin supplementation in the form of injections to control the diabetes.

Initially, your cat may be hospitalised for a few days to deal with any immediate crisis and to begin the stabilisation process. The initial hospitalisation for stabilisation averages from two days to one week or more.  Time is needed to formulate a regime that suits your cat and discover the necessary amount of insulin needed to maintain normal blood sugar levels.  Cats with advanced, untreated diabetes will become very ill.  They may vomit, stop eating and drinking, and will eventually fall into a coma.   Cats in this state, called ketoacidosis, often require a week or more of hospitalisation, intensive fluid therapy and laboratory tests.  Once stabilised your cat will return home for you to continue to administer the required medication. At first, return visits are required frequently to monitor progress.   Once your cat is settled into a regime only periodic blood tests and check-ups will be required to monitor progress.

The financial commitment may again be significant if complications arise. We will work with you to try and achieve consistent regulation, but a few 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. Another complication that can arise is hypoglycemia, or low blood sugar. If severe, this can be fatal. This may occur due to inconsistencies in treatment. This will be explained in subsequent paragraphs.

Your personal commitment to treating your cat is very important in maintaining regulation and preventing crises. Most diabetic cats require insulin injections once or even twice daily. 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 before deciding to commence treatment.

Consistency is vital to proper management of the diabetic cat. Your cat needs consistent administration of medication, consistent feeding, and a stable, stress-free lifestyle. 

1. Insulin does not cause pain when it is injected.

2. The injections are made with very tiny needles that your cat hardly feels. The injected volumes are minute.

3. The injections are given just under the skin in areas in which it is 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.

About Insulin

Insulin comes in an small, airtight bottle.  As it 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. It is not ruined if left out of the refrigerator for a day or two, although this is not advisable. Insulin is safe as long as it is used as directed, but it should be kept out of the reach of children.

Drawing the insulin into the syringe:

1. Shake the bottle to mix the contents. Some of the types of insulin used in cats have a strong tendency to settle out of suspension. If it is not shaken properly it will not mix well, and dosing will not be accurate. Therefore, the trick is to shake it vigorously 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 about foam formation.

2. Remove the guard from the needle, and draw back the plunger to the appropriate dose level.

3. Carefully insert the needle into the bottle through the centre of the rubber lid.

4. Inject air into the bottle; this prevents a vacuum from forming within the bottle.

5. Withdraw the correct amount of insulin into the syringe.

6. Before injecting your cat with the insulin, check that there are no air bubbles in the syringe. If you get an air bubble, 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.

7. Check that you have the correct amount of insulin in the syringe. The dose of insulin should be measured to the end of the plunger nearest the needle.

The injection technique is as follows:

1. Hold the syringe in your right hand (switch hands if you are left-handed).

2. Pick up a tented fold of skin from the scruff of your cat's neck (pick a different spot each day).

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. The latter will result in injecting the insulin straight through the skin onto the  floor. 

4. Withdraw the plunger a little to check that you have not entered a blood vessel.  If you see blood in the barrel of the syringe withdraw the needle completely and start again.

5. To inject the insulin, place your thumb on the plunger and push it all the way into the syringe barrel.

6. Withdraw the needle from your cat's skin. Immediately place the needle guard over the needle and store the needle and syringe back in the fridge. The needle and syringe can be reused many times over.

7. Stroke your cat to reward it for sitting quietly.

8. Be aware that councils have strict rules about disposal of sharp medical waste material so don't throw the syringe into the rubbish.  We can dispose of them safely for you. 

Note: It is not necessary nor desirable to swab the skin with alcohol first. 

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 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.

How do I check on the progress of my cat?

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

A) Home Monitoring
You will need to monitor your diabetic cat in two ways:

Firstly,  it is important to take note of variations in your cat's

We will provide you with a chart on which you can record many of the above observations.  Always bring this to the surgery when you visit with your cat for a check-up so that the veterinary surgeon can study it, it may help in diagnosing a problem.

Secondly, determining the level of glucose in the urine

This is best done on urine that is passed during the night or first thing in the morning. To collect urine, it is usually easiest to replace the normal cat litter with clean (washed) aquarium gravel at night which will not soak up any urine passed. The urine collected can be tested using specially designed strips. The test only takes a matter of seconds to do and is very simple.  The strips, which we will supply to you, also measure for the presence of ketones in the urine.  Ketones indicate that the diabetes is not properly controlled.  If you detect ketones then we should see your cat for a check-up.  If there is any marked change in the amount of glucose in the urine, this may indicate the need to alter the insulin dose. Changes in the insulin dose are usually based on trends in urine glucose concentrations as there is normally some day-to-day variation.   

B) Veterinary Monitoring 
Determining the level of glucose in the blood is the most accurate means of monitoring. This should be done about every 3-4 months if your cat seems to be well regulated. It should also be done at any time the clinical signs of diabetes are present or if appreciable amounts of glucose are detected in the urine for several days.

Timing is important when the blood glucose is determined. Since eating will elevate the blood sugar for several hours, it is best to test the blood at least 6 hours after eating.  As the blood glucose levels vary throughout the day we usually need to take several blood glucose measurements to get an accurate picture.  We are mostly interested in what the highest and lowest glucose readings are for the day.

If your cat is to be admitted for the day for blood glucose monitoring then please follow this procedure:

1. Bring your cat to the hospital at 8.30 am without giving it insulin or food.

2. Please bring your cat's usual food, insulin and daily regime (bring your chart) 

3. A blood sample will be taken immediately, then we will feed your cat and give insulin.

4. Several blood samples will be taken at regular intervals throughout the day to help us determine when the insulin has its peak effect.

5. 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. If this occurs, it is best to admit your cat to the hospital the morning (or afternoon) before testing so it can settle down for testing the next day. In this way the tests are likely to be more accurate.

Does hypoglycaemia (low blood sugar) occur in cats?

Yes, and it can be life-threatening.  It occurs under two 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. If your cat does not eat, you need to call your veterinarian. 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.

The most likely time that a cat will become hypoglycaemic 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 it 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 notice it, telephone and we will organise blood tests.

If your cat is slow to recover from this period of lethargy, you can try feeding sugar or glucose. A teaspoonful of sugar in a little water given as a drink should bring about an improvement. If not repeat it after 15 minutes.  If there is still no response  contact us immediately for further instructions. 

If severe hypoglycaemia occurs, a cat will have seizures or lose consciousness.  If this happens smear honey or glucose syrup on the gums THEN CALL US IMMEDIATELY, THIS IS AN EMERGENCY.   This can only be reversed with intravenous administration of glucose.