DIABETES MELLITUS

In order to understand the problems involved in diabetes mellitus it is necessary to understand something of the normal body's metabolism.

The pancreas is nestled along the stomach and small intestine. It secretes digestive enzymes into the small intestine but it also secretes hormones into the bloodstream to regulate blood sugar.

The cells of the body require a sugar known as glucose for food and they depend on the bloodstream to bring glucose to them. They cannot, however, absorb and utilize glucose unless a hormone known as insulin is present. This special hormone, insulin, is produced by the pancreas. Insulin can be considered to be a key that unlocks the door separating our cells from the sugars in our bloodstream.

Glucose comes from the diet. When an animal goes without food, the body must break down fat, stored starches, and protein to supply calories for the hungry cells. Proteins and starches may be converted into glucose. Fat, however, requires different processing which can lead to the production of ketones rather than glucose. Ketones are another type of fuel which the body can use in a pinch but the detection of ketones indicates that something very wrong is happening in the patient's metabolism. Ketones may be detected in the urine of starving animals as massive fat mobilization is required for ketone formation. Ketones can also be detected in diabetic ketoacidosis, a severe complication of unregulated diabetes so it is helpful to periodically monitor for ketones in a diabetic patient’s urine.

Urine dipsticks to detect ketones are available at most drug stores and can be used for home monitoring. The presence of ketones in urine for three days or more in a row warrants a visit to the veterinarian

• The cells cannot receive glucose from the blood because there is no insulin to permit it.
  
  
• The body is unable to detect the glucose present in the blood and is fooled into thinking starvation is occurring.
  
  
• Protein, starch, and fat break-down occurs as in starvation.
  
  
• Yet, all along there has been plenty of glucose in the blood. In fact, by now, there is a large excess of glucose in the blood as all resources have been mobilized. Still, without insulin, this bounty of fuel cannot get to the tissues that need it.
  
  
• The normal kidney is able to prevent glucose loss in urine. In the diabetic animal, there is so much glucose in the blood that the kidney is overwhelmed and glucose spills into the urine and is lost.
  
  
• Glucose is able to draw water with it into the urine. This leads to excess urine production and excess thirst to keep up with the fluid loss in excess urine production.
  
  

• Excessive eating
  
  
• Excessive drinking
  
  
• Excessive urination
  
  
• Weight loss
  
  

It is usually fairly clear from the history and tests showing dramatic glucose elevations in the blood (and usually the presence of glucose in the urine, too) that diabetes mellitus is the diagnosis. Some pets are able to substantially raise their blood sugars from stress (such as might occur when a sensitive, sick, and anxious patient goes the vet’s office). This could create misleading test results. If there is any question about the diagnosis, a test called a fructosamine level may be requested. This test reflects an average blood glucose level over the past several weeks so if this is also elevated, a one time elevated glucose can be distinguished from the persistant elevations of true diabetes mellitus. The fructosamine test is also used in monitoring therapy for diabetes mellitus.

• Note, in the dog, sugars can enter the lens of the eye causing rapid cataract formation. Because the lens of the cat is different, this phenomenon occurs only in dogs.
  
  
• 1Another common symptom of diabetes mellitus is urinary tract infection. All the sugar in the urine makes the bladder an excellent incubator for bacteria. Antibiotics are necessary to clear up such an infection when it occurs and some monitoring may be needed to help detect these infections.

Diabetes mellitus is a classical disease in humans and most of us have heard some of the terms used in its description. In humans, diabetes is broken down into two forms: Type I and Type II. These are also referred to as "juvenile onset" and "adult onset" diabetes or "insulin dependent" and "non-insulin dependent” diabetes. In short, type 1 is the type where the pancreas produces no insulin at all, and type 2 is the type where the pancreas produces some insulin but not enough. Virtually all dogs have "insulin dependent diabetes" and must be treated with insulin. Most cats have "non-insulin dependent diabetes." This might suggest that most cats can get away without insulin injections but that is not the case at all. Instead, for cats, there is potential for the diabetes to actually resolve if the pancreas improves its insulin-secreting ability. Insulin injections are needed to treat most diabetic cats but for some cats, the situation is mild enough for oral medication to suffice. Good glucose control and proper diet can resolve the diabetes in some lucky cats but virtually never in diabetic dogs.

Typically diabetes mellitus is seen in obese cats that are middle aged or older, and more commonly in males (the opposite of dogs). There is no specific breed predilection in cats.Dogs are typically middle aged and older, with purebred dogs showing a higher incidence. Common breeds are: Miniature Schnauzers, Labrador retrievers, and Miniature poodles.

Physical Examination

The findings of the physical exam depend on how severe the diabetes is, how long it has been present, what caused it, and if there are any other disease processes occurring simultaneously.

Many pets will have lost weight, yet they still could be obese. There might be dehydration, weakness, lethargy, an enlarged liver on abdominal palpation, and an acetone (juicy fruit) smell to the breath. Hypothermia and shock could be present in advanced cases.

Diagnostic Tests

The primary method of diagnosis is with a blood panel and a urinalysis. The blood panel will reveal hyperglycemia (elevated levels of glucose in the blood) while the urine sample will reveal glycosuria (glucose in the urine). Not every case of hyperglycemia means a pet has diabetes mellitus. Pets that recently ate, or those that eat canned foods that are rich in sugar, might have blood glucose levels higher than the normal range. Pets that are on cortisone, are in heat, on phenobarbital medication or hormone medications might also have hyperglycemia.

Cats are unique in that their stress response can cause a tremendous rise (up to 4x normal) in the blood glucose. This is a common occurrence when we take a blood sample in a cat and needs to taken into consideration when we analyze a blood report. This stress induced response is a normal reaction to the release of epinephrine (adrenaline). It is a transitory response and will not persist like the hyperglycemia of diabetes mellitus. These cats sometimes need to adjust to a hospital environment before we are able to determine their true blood glucose level.

This cat has diabetes mellitus, its blood glucose is 390.

Diabetes mellitus is diagnosed when there is a persistent fasting elevated blood glucose levels along with glucose in the urine, that is consistent with a history of excessive drinking and urination and excessive appetite.

Other blood tests are sometimes used in this disease. The two more common ones are serum fructosamine and glycosylated hemoglobin. They are used to to distinguish stress induced hyperglycemia from diabetes mellitus, and to also monitor insulin therapy. They give us an indication of what the blood glucose level has been for the preceeding weeks.

In addition to glucose in the urine and ketones, the urinalysis might indicate that a urinary tract infection is present. This is detected by a change in the pH of the urine, excess white or red blood cells, and bacteria.

First, an insulin type and dose will need to be selected. There are several types of insulins to select from and it is not possible to know how much insulin your individual pet will require. Your veterinarian can make a guess based on what works for other cats and dogs and what has been reported in the literature. Most pets require injections twice a day, approximately 12 hours apart, following a meal.

You will need to learn how to give insulin injections to your pet. The technique of subcutaneous insulin administration should be thoroughly demonstrated by your doctor or a veterinary technician. Be sure you know how to hold the bottle, manipulate the syringe, hold your pet, and give the injection. Some situations require that the pet be hospitalized for a few days for the initial regulation but most of the time your pet will be at home receiving injections shortly after the diagnosis has been reached.

Some insulins are available from the neighborhood pharmacy and some kinds are available only through veterinary offices and veterinary pharmacies. You will need syringes and bottle of insulin to begin home treatment. Your veterinarian will either provide you with supplies or will give you the necessary prescriptions. Insulin syringes are marked in insulin units so the insulin syringes must match the insulin concentrations (either “U-100” syringes for 100 unit/cc insulins or “U-40” syringes for 40 unit/cc insulins.) Whenever you receive more supplies, always double check these numbers.

Insulin Injections

It is imperative that you administer the precise amount of insulin required since small changes can have dramatic effects in the cat. Be consistent and give the insulin the same time and at the same location every day. If your cat is on twice daily insulin injections give each morning and evening dose at the same time every day. always feed your cat in the morning prior to giving the insulin. If it does not eat its food skip the morning dose of insulin. If it eats only half of its food, give it only half of its insulin dose. Giving a normal dose of insulin to a cat that is not eating greatly increases the risk of hypoglycemia. You must always err on the side of hyperglycemia instead of hypoglycemia.

A record should be kept of your pet's food intake to note any changes. The same thing holds for its water consumption.

The actual administration of insulin is very straightforward. As a matter of fact, it is easier to give insulin injections at home than it is to give SQ (subcutaneous) fluids to cats that have chronic renal failure, a common finding in our hospital. This is because an insulin injection takes 1 second to give, whereas fluids take 5-10 minutes. The technique used to give insulin injections or SQ fluids is the same.

In order to simplify the process we will give you an insulin syringe that has been designed to be used with the specific type of insulin your pet requires. You will be giving insulin in a measurement called "units", and not in ml (milliliters) or cc (cubic centimeters) as is commonly used in most syringes. A typical insulin syringe is called U-100 or a U-40.

This is what a U-100 syringe looks like. The needle is very small and sharp so your cat will not feel it during its injection.

Insulin should be kept refrigerated at all times to preserve its freshness. Prior to use it should be gently warmed in your hands. Gently roll it (never shake it vigorously because excess bubbles will form) between your hands for 1-2 minutes to bring it to the proper temperature for administration. Storing the insulin bottle on its side in the refrigerator will help in mixing.

Make sure you are in a relatively calm location when you give the injection. Hold the insulin bottle upside down and draw out slightly more than the number of units your pet requires. Tap the syringe a few times to remove any air bubbles-this aids in accuracy. Push the plunger in the syringe slightly forward until you have the exact number of units you need to administer is in the syringe. Put the cap back on the syringe and put the insulin bottle back in the refrigerator. Do not reuse the syringe.

Give the injection in the scruff of the neck just as you would when giving SQ fluids. Your pet should not feel anything because the needle is so tiny and sharp. The whole process, from warming the insulin to giving the injections, should only take a couple of minutes. As you get confidence it is recommended to rotate your injection sites.

Improper administration of insulin is one of the most common causes for improper regulation. Please do not hesitate to contact us at any time for assistance in this vital procedure.

Never alter the insulin dose recommended by your doctor. To determine whether dose adjustments are needed (or even a different type of insulin would be more appropriate), the pet will need a "glucose curve" where blood sugar levels are monitored every 2-4 hours or so for 12-24 hours. This kind of testing tells the doctor how long the insulin injection is lasting as well as what the lowest and highest glucoses of the day are. It is important to find out when your pet's curve is due. Often in the beginning, it takes several doses selections and several curves before the right dose is determined.

Not every pet is amenable to getting pricked with a lancet so that a drop of blood can be harvested for testing. We do not want your pet to fear interaction with you and do not want you to get bitten or scratched; still, some pets are very comfortable with periodic glucose monitoring at home. Home testing may work best for pets that become so agitated by the trip to the vet that their blood sugar levels are altered at the vet’s office and cannot be interpreted. Further, a pet owner can save a great of deal of money if they can produce their own glucose curve at home when the veterinarian requests one.

Human glucose meters can be obtained from any drugstore but ideally the AlphaTrak glucometer should be obtained as it is designed especially for pet use. The AlphaTrak is more accurate in cats and dogs than the human equipment; though certainly the human equipment was all that was available for decades and worked sufficiently. If you would like to get an AlphaTrak meter, contact your veterinarian.

If you choose to use a glucometer at home, be sure to keep a log of when your pet was fed, when insulin was given, and what the glucose levels were that you found. Bring this log to your veterinarian when you come for check ups. Glucose levels obtained prior to the first insulin administration of the day are particularly useful.

If your pet is too sensitive for a valid glucose curve at the vet’s office and you do not think you are up to blood sugar testing at home, the fructosamine blood test may be particularly useful. Again, this test looks at average glucose levels so wide fluctuations will not be discovered but at least there is a monitoring option for this situation.

Ketostix can be obtained at any drug store and are used to detect ketones in urine. If it is not difficult to access your pet’s urine, a first morning test is helpful. Remember, the occasional presence of ketones is not a problem but a positive dipstick three days in a row is a criterion for a vet visit.

Home Monitoring

The best way to monitor your pets blood glucose at home is to perform the blood glucose yourself. Ears and feet pads are areas in which a small prick will give sufficient amount of blood to run an in home blood glucose. Some of our clients use a home glucose kit to check their pet’s glucose levels. It is easy to do once we show you, and gives a more accurate assessment of blood glucose levels at home than does the glucose in the urine.

To use the glucometer you need to find an ear vein. You can see this one running horizontally under the veterinary technician’s finger.

It is very simple to prick the ear with this machine and get your sample.

You only need a few drops of blood for the glucometer. After you place a drop of the blood in the tip the machine will give you a blood glucose reading in a few seconds.

Most people prefer to monitor the glucose in their cat's urine because it is simpler. Monitoring of the glucose in your cats urine will give you at best a rough idea of its blood glucose level. However, there are significant limitations to home monitoring using urine glucose as a criteria. Urine glucose measurements do not necessarily correlate with blood glucose measurements, the more important of the two.

To help in the urine monitoring process your cat's normal litter can be replaced with special litter that will not absorb urine. You can also use regular paper, newspaper, or even plastic wrap in the bottom of the cage. There is even a special litter that reacts with the glucose in the urine.

One of the more common urine dipstick kits is the Keto-Diastix. In addition to monitoring glucose it also monitors for ketones.

This is the chart on the Keto-Diastix bottle. The box to the far left is negative, which is the goal. The next box to the right is 100 mg/dl. Its OK to have this urine glucose value on occasion.

On the same bottle there is a chart to monitor for ketones in the urine. Your goal is to have negative with an occasional trace.

What is just as important as urine glucose is your subjective interpretation of how your cat is doing. If the original symptoms are greatly reduced then you are probably giving an accurate dose.

Determining the daily dose of insulin required at home is not an easy task. We have learned over the years that blood glucose determinations are variable, and that in many cases it is your perception at how well you pet is eating, how active it is, and how its drinking and urinating has decreased that is more important. A more accurate blood test is the fructosamine level, which gives us an average of your pets blood glucose levels of the last 2-3 weeks, and is much less variable than individual blood glucose determinations.

Do not make any changes in insulin dose unless you talk with one of our doctors. Do not make daily changes in insulin doses either, wait 3 days to determine if the new dose is having any effect.

Warning signs that necessitate an exam and blood glucose curve in the hospital:

• Lethargy or significant increase or decrease in appetite
• Significant increase in drinking or urinating
• (100 mg/dl) or more glycosuria for > 2 days
• Significant ketones in urine for > 2 days

Regulation is achieved via a balance of diet, excercise, and insulin. Realizing that special diets are not always attractive to pets, there are some ideal foods which should at least be offered.

The most up-to-date choice for cats is a low carbohydrate high protein diet such as Hill’s M/D diet or Purina’s DM diet. These diets promote weight loss in obese diabetics and are available in both canned and dry formulations. For dogs, high fiber diets are still in favor as fiber seems to help sensitize the pet to insulin.

One should avoid soft-moist diets as sugars are used to preserve them. Breads and sweet treats should be avoided. If it is not possible to change the pet’s diet, then regulation will just have to be worked out around whatever the pet will eat.

Your pet will probably require re-regulation at some point. During re-regulation periods, expect a glucose curve to be run a week or two after each adjustment in insulin dose. A blood glucose curve is a graph of blood glucose levels over time. It is the most effective way to determine the type, dose, and frequency of administration of insulin, necessary to keep the blood glucose at acceptable levels. Each pet responds very differently to insulin, and so the appropriate insulin therapy must be determined for each individual animal. In addition, a pet's insulin needs may change dramatically over time, so blood glucose profiles may need to be performed periodically for the lifetime of the animal.

Bring your pet in for a re-check exam and glucose curve if you note any of the following:

• the pet seems to feel ill.
• the pet is losing weight.
• the pet has a ravenous appetite or loses its appetite.
• the pet seems to be drinking or urinating excessively.
• the pet becomes disoriented or groggy.
• the presence of ketones in the urine for three days in a row.

If your pet appears wobbly or drunken, his/her blood sugar level may have dropped too low. This occurs after an insulin overdose. First try to get your pet to eat. If the pet will not eat, administer light Karo syrup at a dose of one tablespoon per 5 pounds. If no improvement occurs, immediately see your veterinarian for emergency treatment. When your pet is more stable, a glucose curve will be needed to determine a more appropriate insulin dose).

Some pets seem to require re-regulation frequently. There may be an underlying reason to sort out. Here are some possibilities should your pet seem to fit in this category:

1. Improper administration of insulin. If possible, have your doctor observe you giving the insulin to your pet. Your insulin may be out of date.
   
   
2. Rapid insulin metabolism. Insulin wears off quickly in some animals. Your pet may require a different type of insulin or a second injection during the day.
   
   
3. Insulin overdose may actually lead to elevated glucose levels (and clinical signs of diabetes mellitus) at the end of the day. In these cases, excess drinking, eating, or urinating are seen in the afternoon and evening but not in the morning.
   
   
4. Steroid administration (such as prednisone, prednisolone etc.) will interfere with insulin.
   
   
5. Progesterone, a female hormone, also interferes with insulin. Unspayed female diabetics should be spayed once they are sufficiently regulated.

Long Term Care

It must be understood that insulin administration does not cure diabetes mellitus, it only controls it. The body has very sophisticated and refined mechanisms to keep the blood glucose at optimum levels. This cannot be replicated easily by giving insulin.

To minimize problems we should monitor your pet's blood glucose level in the hospital and perform a urinalysis every 3 months. Since pets can exhibit an exaggerated stress response causing a profound hyperglycemia a glucose curve is necessary to ensure accuracy. Every 6 months we should also perform a complete blood panel to look for changes in other organs caused by the diabetes. A further reason to run a complete blood panel every 6 months is to monitor routine age related changes like hyperthyroidism and kidney disease. Diabetes can also predispose your pet to high blood pressure (hypertension).

This long term monitoring is important for another reason. In almost every diabetic pet insulin requirements change, necessitating the need for close monitoring and communication with us. If your pet goes into heat (another reason to spay females and even neuter males) its insulin requirements might change. In some diabetic cats the problem goes away and they no longer have a need for insulin. Giving insulin to these cats can cause hypoglycemia, which if it is severe enough, can lead to seizures.

Complications of Diabetes

Hypoglycemia

One of the more alarming side effects to insulin administration is hypoglycemia. Symptoms include shaking, a starry eyed appearance, lethargy, shaking, greatly enlarged pupils, muscle tremors and even seizures. A pet with these symptoms should be taken to a veterinarian immediately.

In most cases the cause is an overdose of insulin. A common scenario involves a cat that eats significantly less than its normal amount for the day. Hypoglycemia can result if the dose of insulin is not adjusted to take this into account. If your cat is not eating well and you are unsure, either give less insulin that day or do not give any at all. A blood glucose test in the hospital will let us know for sure.Other causes of hypoglycemia include improper insulin administration resulting in an accidental overdose, along with cats that spontaneously recover from their diabetes and no longer need insulin.

Liver Disease

Cats with diabetes are forced into using an energy source that will eventually cause a fatty infiltration of liver cells. As a result the liver will not function at optimum capacity, a potentially serious problem since the liver is such a vital organ. The liver enzyme test on the blood panel will alert us to this complication. When the diabetes is treated this problem might resolve.

Radiography might reveal an enlarged liver (hepatomegaly) due to the fatty infiltration. This liver is larger than normal-it is extending towards the right far beyond the margin of the ribs. The 4 white arrows on the bottom outline the lower edge of the wedge shaped and enlarged liver.

One of the most important disease syndromes associated with a fatty liver is called hepatic lipidosis. It occurs in overweight cats that are exposed to a stress that causes them to stop eating. This lack of appetite can become so severe that a feeding tube needs to be put in.

Infections

Diabetic pets are prone to infections, especially of the urinary tract. Good dental hygiene is critical also since many pets with diabetes have dental disease. Chronic dental disease can make regulation almost impossible.

Summary

Diabetes is a complex disease that requires diligence on your part for proper control. Since every pet is different, your doctor will make a custom plan that will work for you and your pet, and will not necessarily follow any pre-established protocol. Be prepared for constantly changing insulin requirements and potential complications. The more consistent you are with feeding the same food, in the same amount, at the same time(s) every day, will add to a successful outcome.

The majority of diabetic pets on insulin therapy have a significantly increased quality of life. This usually makes the time and economic commitment necessary for proper regulation well worth the effort.

• www.felinediabetes.com
• www.caninediabetes.org