DIABETES MELLITUS

DIABETES MELLITUS

What is Diabetes Mellitus?

Diabetes mellitus is the correct term used to describe the medical condition that is commonly known as "sugar diabetes". "Diabetes" is a general term used to refer to a variety of disorders characterized by increased urine production (or polyuria) and increased water intake (or polydipsia). It is derived from the Greek words dia which means "through" and bainein which means "go". The term "mellitus" is derived from the Latin word mel which means "honey".

Diabetes mellitus is a complex metabolic disorder of carbohydrate, fat, and protein metabolism caused by a deficiency of the hormone, insulin. The pancreas is a small but vital organ that is located near the stomach. It consists of several types of cells. One group of cells called acinar cells produce the enzymes necessary for proper digestion. Another group, called beta-cells, produce insulin. Simply put, diabetes mellitus is a failure of the pancreas to regulate blood sugar.

There are essentially two forms of diabetes mellitus. 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:

Type I, or Insulin Dependent Diabetes Mellitus

results from very low or absent insulin secretion secondary to the total or near-total destruction of the beta-cells

this is the most common form of diabetes mellitus seen in dogs and cats

Type II, or Non-Insulin Dependent Diabetes Mellitus

in this form the beta-cells are present but the amount of insulin they produce is reduced or there is a delayed response in secreting it, or the muscle, fat and other tissues become "resistant" to insulin's effect

this form is only rarely diagnosed in dogs and cats

up to 40% of cats with Type II diabetes mellitus will regain the ability to control their blood glucose level and require no further treatment but this may take months to years, during which period treatment is required

Why is insulin so important?

Insulin is required by muscles, fat tissue and the liver to utilise the carbohydrates, proteins and fats ingested in the diet.

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 is unable to get into the cells and it accumulates in the blood, leading to high blood sugar or hyperglycaemia. When insulin is deficient, the cells become starved for a source of energy. In response to this, the body starts to breakdown stores of fat and protein to use as alternative energy sources. This leads to a series of metabolic changes that result in the signs of diabetes mellitus developing.

How common is Diabetes Mellitus?

Diabetes mellitus is a relatively common disorder and is diagnosed in approximately 1 in every 400 to 500 dogs and cats.

Is my pet at risk of developing Diabetes Mellitus?

It is known that certain breeds of dogs have a higher risk of developing diabetes mellitus than others. These include the Poodle, Dachshund, Miniature Schnauzer, Beagle, King Charles Cavalier Spaniel, Scottish Terrier, Miniature Pinscher and Cairn Terrier. Diabetes mellitus in the Keeshond is an inherited condition ie. is passed from one generation to the next.

No apparent breed predilections have been noted in cats.

Female dogs are diagnosed with diabetes mellitus twice as much as male dogs. Male cats (particularly desexed) are more likely to develop the disorder than female cats.

The average age of dogs that develop diabetes mellitus is 8 years. It is rare for dogs under 6 months of age to become diabetic. 75% of cats that are diagnosed with diabetes mellitus are 8 to 13 years of age.

Overweight dogs and cats have a higher risk of suffering from diabetes mellitus.

What causes Diabetes Mellitus?

The exact cause of diabetes mellitus may not be determined in every case and there are still causes of diabetes mellitus that are unknown. Some of the causes are thought to be:

Genetic susceptibility

as already stated, certain breeds of dogs are at greater risk of developing the disorder

Infectious diseases

viral infections may cause destruction of the beta-cells within the pancreas

Immune-mediated disease

the animal's own immune system may start to attack and destroy the beta-cells within the pancreas

Pancreatitis

this is a relatively common inflammatory condition of the pancreas, particularly in dogs

inflammation results in damage and scarring of the pancreas that, if severe enough, can result in loss of beta-cells

Predisposing diseases

dogs and cats with other underlying diseases (such as a syndrome known as Cushing's disease) are more at risk of developing diabetes mellitus

Drugs

medications such as cortisone and progesterones can predispose an animal to developing diabetes mellitus

Obesity

Cancer of the pancreas

What are the signs of Diabetes Mellitus?

There are four classic signs of diabetes mellitus. They are:

Increased drinking (polydipsia)

Increased urination (polyuria)

Increased appetite (polyphagia)

Weight loss

These signs may take a few weeks to a few months to become noticeable.

Other signs that can develop later in the disease syndrome include:

Anorexia

Lethargy and depression

Vomiting and/or diarrhoea

Muscle wastage along the back in cats

Oily coat with dandruff in cats

Sudden onset of cataracts

Blindness secondary to degeneration of the retina in the eye

Coma and death

Unusual hind limb gait

is seen only in cats

affected cats walk with their hocks (or ankles) touching the ground

Anorexia, lethargy, depression, vomiting, diarrhoea and coma are all indications of a life-threatening form of diabetes mellitus called ketoacidosis. Ketoacidosis occurs in those diabetic animals that are not treated soon enough or correctly. It represents a very serious disruption to the animal's metabolism and will most likely result in the animal's death if left untreated.

Why does my diabetic pet drink and urinate so much?

Blood is made up of two components. These are:

Cellular component

contains such cells as red blood cells and white blood cells

Fluid component

is called plasma

contains a large amount of dissolved chemicals and nutrients

The kidneys act as one of the blood's filter systems. Blood passes through the kidneys and is separated into its cellular and fluid components. Waste materials and toxins are removed from the blood by the kidneys and excreted from the body in the urine. Along with these wastes and toxins, nutrients such as glucose also pass into the urine. In a normal animal, the kidney reabsorbs all of these useful nutrients so they can be utilised by the body. In diabetic animals excessive amounts of glucose pass into the urine. This excessive amount overwhelms the kidneys' ability to reabsorb the glucose. The glucose in the urine attracts more water from the fluid component of the blood into the urine via a process called osmosis. As a result an increased amount of urine is produced. To avoid dehydration from the excessive urine production the animal must drink increasing amounts of water.

Why is my diabetic pet always hungry but has lost weight?

The liver, fat tissue and muscle of the body rely on insulin to allow glucose to pass from the blood stream into the cells so the glucose can be used for energy. Without the glucose the cells essentially "starve". This results in weight loss. As a response to this, the part of the brain known as the "feeding centre" is stimulated to increase the amount of food consumed. In addition to this, the part of the brain called the "satiety centre" is switched off. The "satiety centre" is responsible for creating the sensation of having eaten enough after a meal. This sensation is caused by an increase in the blood sugar after a meal resulting in more glucose passing into the "satiety centre" and switching it on. The passage of the glucose is controlled by insulin. Because diabetic animals have no insulin the glucose is unable to pass into the "satiety centre" and thus it is not switched on and the animal will continue to eat.

How is Diabetes Mellitus diagnosed?

Diabetes mellitus is diagnosed on the basis of:

The animal's symptoms

An abnormally high blood glucose measurement

the normal level of glucose in the blood is 4 to 7 mmol/L

diabetes mellitus is the only common disease that will cause blood glucose levels to rise above and stay above this normal level

Diabetes mellitus is not the only cause of an elevated blood glucose measurement. Stress, particularly in cats, is a common cause of an increased blood glucose level. This increase does not persist but in certain cases it may be difficult to distinguish if the high blood glucose level is due to diabetes mellitus or to stress. An analysis of the animal's urine may be performed. Diabetic animals will consistently have large amounts of glucose in their urine. Alternatively, a blood test to determine the level of a protein called fructosamine can give an indication of the animal's blood glucose level for the previous 3 weeks. Diabetic animals have an increased fructosamine level while those animals with an elevated blood glucose level due to stress have a normal fructosamine level.

Because diabetes mellitus is such a complex disease there are often other metabolic abnormalities or diseases occurring in conjunction with an elevated blood glucose level. These include various degrees of liver dysfunction, dehydration, inflammation, electrolyte abnormalities and urinary tract infections. As a consequence of this, it is often necessary to perform more extensive blood tests to assess the animal's overall health before the correct treatment can be given. These tests are performed at Karingal Veterinary Hospital using our IDEXX VetLabÔ equipment.

How is Diabetes Mellitus treated?

Before deciding to treat their diabetic pet an owner MUST consider two important factors:

Personal commitment

diabetes mellitus CANNOT be cured and as such the animal will require DAILY medication for the REMAINDER OF ITS LIFE
this means, for example, if you go away on holidays then someone has to be organised to give your pet its medication
the aim of treatment is to manage the diabetes mellitus so that the animal is as close to normal as possible

Financial commitment

the cost of treating a diabetic dog or cat can vary depending on how sick the animal is when it is diagnosed with diabetes mellitus

once the animal is stabilised the costs are relatively constant

the initial treatment costs and the cost of ongoing treatment will be explained to you to allow you to make a decision on whether you want to treat your diabetic pet or not

These factors should be considered carefully before deciding to commence treatment.

Treating diabetes mellitus can be classified into 4 main areas.

Intensive Care Treatment

This is only necessary if the animal is severely affected by the diabetes (ie. is dehydrated or is ketoacidotic) as this can be a life-threatening situation. Treatment involves hospitalisation and the administration of intravenous fluids, insulin and other medications to try and return the animal's metabolic state back to normal. Once this is achieved then long-term control of the diabetes can be started. Such intensive care treatment can take 2-4 days and cost at least $450-500. In the majority of cases, newly diagnosed diabetic animals do not require such intensive treatment.

Diet

The type, amount and time the food is given all affect the treatment of the diabetes.

The ideal type of food for animals with diabetes mellitus is one that is high in fibre, low in fat and high in complex carbohydrates. There are several reasons for this:

These diets reduce the risk of the animal becoming obese

overweight diabetic animals are more difficult to stabilise and control their diabetes as they require more insulin and they can develop resistance to the insulin's effects

These diets take a longer time to be digested

this means that the glucose in the food is more slowly absorbed from the intestine into the blood stream

the result of this is that there is not a sudden surge in the blood glucose level after eating and thus the animal does not have to process a large amount of glucose at one time

this makes controlling diabetes mellitus easier

Soft, moist foods (ie. canned foods) tend to be low in fibre, high in fat and contain low amounts of complex carbohydrates and for these reasons should be avoided

The problem with diets that are high in fibre, low in fat and high in complex carbohydrates is that they are often not very palatable and animals will not eat them! The aim is to feed them a consistent diet that they will reliably eat. Obese animals should be fed a diet that will result in gradual weight loss over 2-3 months. All diabetic animals should be regularly weighed.

Diabetic animals should be fed the same amount of food each day. It is best to weigh out or measure the food each day rather than guessing the amount. This ensures the animal eats the same amount of glucose each day allowing for more accurate control of the diabetes.

The timing of feeding is also very important. It is best to feed animals with diabetes mellitus twice daily. The animal should be fed 1/2 its daily food intake in the morning (preferably at the about the same time each day) and the other 1/2 some 8-10 hours later. Treats and scavenging of food should be avoided.

Activity

Diabetic animals should receive a similar amount of exercise each day. Variations in the amount of exercise will alter the animal's energy requirement. This in turn will vary the glucose requirement and effect the control of the diabetes

Insulin

The administration of insulin is the most important aspect of controlling diabetes mellitus. A diabetic animal will require insulin injections every day for the rest of its life - this means you will have to give them! Most animals require only one injection of insulin per day though occasionally two may be needed. Your Veterinarian will determine this.

Once your pet has been diagnosed with diabetes mellitus, the attending Veterinarian will inject your pet with a certain amount of insulin and then take several blood glucose measurements during the day. These measurements give the Veterinarian an indication of what effect the dose of insulin has had and whether the dose needs to be increased or decreased. Once the dose has been determined then you will be shown how to administer the insulin and your pet will be sent home. In the initial stages of treatment you will need to bring your pet into the Hospital fairly regularly to have the blood glucose measurements taken. The Veterinarian will determine the frequency of these visits. As the diabetes becomes stabilised, these visits will become less frequent and ultimately may only have to be performed every 4-6 months.

Some important points about insulin

Insulin comes in an airtight bottle that is labeled with the insulin type and the concentration. The concentration of insulin is measured as Units per ml. At Karingal Veterinary Hospital we use two different types of insulin. Caninsulin contains insulin at 40 Units per ml and is used for cats and small dogs. Monotard insulin contains insulin at 100 Units per ml. It is more concentrated and so not as much needs to be injected. It is used for medium to large dogs.

Insulin can settle over a few hours and you may notice a white layer in the bottom of the insulin bottle. The bottle should be well shaken before use. If it is not shaken well, it will not mix well and dosing will be inaccurate.

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. It will not be ruined if left out of the refrigerator for a day or two, although this is not advisable.

As with all drugs, insulin should be used only as directed and kept out of reach of children.

How do I inject the insulin?

Many people are initially afraid of giving insulin injections. If this is your initial reaction then consider these points:

Insulin does not cause pain when it is injected

The injections are made with very tiny needles that your pet will hardly feel.

The amount that is to be injected is very small

The injections are given just under the skin in areas where it is almost impossible to cause damage to any vital organ.

While giving injections may seem daunting at first you will be surprised how quickly it will become second nature to you and your pet.

Drawing up insulin from the bottle

Remove the guard from the needle and draw back the plunger of the syringe to the appropriate dose level

Carefully insert the needle into the insulin bottle and turn the bottle upside down

Inject the air in the syringe into the bottle

this prevents a vacuum forming within the bottle which will make it increasingly more difficult to withdraw the insulin

Withdraw more than the appropriate dose of insulin into the syringe

Gently tap the syringe with your finger to ensure there are no air bubbles in the syringe while still holding the bottle upside down

any bubbles present will rise to the tip of the syringe

Inject the excess insulin and any air bubbles back into the bottle and check the correct amount of insulin is in the syringe

Remove the syringe and needle from the bottle and replace the guard on the needle if moving about

Injecting the insulin

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

Pick up a fold of skin from somewhere on your pet's body

ideal places include the back of the neck, over the shoulder blades, just in front of the back legs (the flank region) or over the back

you should choose a different position each day but start with the back of the neck until you become proficient with injecting

you may find it helpful, particularly in long-haired animals, to keep an area shaved or clipped short so you can see the needle go into the skin

Quickly push the very sharp, very thin needle through the animal's skin

this should be easy and painless

take care to push the needle through only one layer of skin and not into your finger or through the other side

To inject the insulin, place your thumb on the plunger and push it all the way into the syringe barrel
Withdraw the needle from the skin and replace the needle guard
Reward your pet with a pat for sitting quietly while you gave the injection

If in the process of injecting you don't get the entire amount of insulin into the animal (eg. the animal moves or you push the needle through the skin) DO NOT give any more insulin. This may result in you overdosing the insulin. A slightly underdosed diabetic is much better than an overdosed one!

It is neither necessary nor desirable to swab the skin with alcohol to "sterilise" it. There are four reasons for this:

Due to the nature of the thick hair coat and the type of bacteria that live near the skin of dogs and cats, brief swabbing with alcohol or any other antiseptic is not very effective

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

The sting caused by the alcohol can make your pet dislike the injections

If you 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.

Disposing of syringes

Insulin syringes can be used 2-4 times before they become blunt. Syringes and needles SHOULD NOT be thrown out in the household rubbish. The best way to dispose of them is to place used needles and syringes in a large, empty soft drink bottle. When the bottle is full bring it into the Hospital and we will dispose of the needles and syringes appropriately.

Are any other drugs used to treat Diabetes Mellitus?

Many people with diabetes mellitus are able to control their condition with tablets that stimulate the pancreas to produce more insulin. These drugs have proved to be ineffective in controlling diabetes in dogs and only moderately successful in cats. Research into a number of other possibly useful drugs is being carried out.

How are diabetic animals monitored?

It is important to closely monitor diabetic animals to ensure their diabetes is under control. There are several ways this is achieved.

Home Monitoring

owners of diabetic animals should be constantly aware of their pet's appetite, weight, water consumption and urine output. Changes in water consumption are a good indicator that re-testing is needed

diabetic animals should be weighed at least each month and it is best to use the same scales each time

normal animals and stabilised diabetics should drink between 50 to 100mls of water per kilogram of body weight per 24 hours

eg. a 20 kg dog should normally drink 1 to 2 litres of water per day

Blood Glucose Measurements

the most accurate way of determining if the diabetes is under control is to measure the animal's blood glucose level throughout the day

as already mentioned, once the diabetes is controlled this should only need to be performed every 4-6 months

Some Veterinarians like to have owners of diabetic animals test the animal's urine daily for the presence of glucose and adjust the dose of insulin accordingly. At Karingal Veterinary Hospital we don't like handling urine and so we don't expect our clients to do so! We also prefer to make adjustments to the insulin dosage ourselves so we can better monitor the amount of insulin the animal is receiving.

What does blood glucose monitoring involve?

The aims of the blood glucose measurements are:

To determine the highest blood glucose level

this is usually in the morning just before the insulin injection is given

To determine the lowest blood glucose level

this is usually 6-8 hours after the insulin injection is given

the aim is to have the blood glucose level drop to between 5 and 10 mmol/L

To determine the duration of action of the insulin ie. how long does the insulin work for?

In order to perform the measurements the animal must be hospitalised for the day to allow the blood samples to be collected at certain times.

Animals should be admitted to the Hospital between 8 and 9am. You should bring with you:

The food the animal would normally be fed at its morning meal

The animal's bottle of insulin and a syringe

DO NOT give your pet its insulin as we will give it when we take the first blood glucose measurement

How long will my pet live with Diabetes Mellitus?

With proper treatment and commitment most diabetic animals can lead a normal life and live to their normal life expectancy.

Once stabilisation has begun you should see a reduction in your pet's water intake and urine production within a few days. After a few weeks your pet's appetite should return to normal and their weight should begin to normalize.

Does hypoglycaemia occur in cats and dogs?

Hypoglycaemia is the correct name for low blood sugar. Hypoglycaemia occurs in diabetic animals for 2 reasons:

The insulin dose is too high

although most animals require the same dose of insulin for long periods of time, it is possible for their insulin requirements to change

the most common cause for this change is a reduction in food intake and an increase in exercise or activity

Too much insulin is given

this occurs if the amount drawn out was incorrect or two family members give the animal the insulin without realising that the other person already has

The most likely time that an animal will become hypoglycaemic is 6-8 hours after the insulin is given. This is when the insulin has its peak effect.

The early signs of hypoglycaemia include weakness and lethargy. This progresses to shaking and unsteadiness. In severe cases the animal may start to have seizures, slip into a coma and die.

Should your pet show any weakness or lethargy then place a teaspoon of sugar in a little water and pour it into the animal's mouth or rub some honey or glucose syrup onto the animal's gums. If the symptoms are more severe then THIS IS AN EMERGENCY and a Veterinarian should immediately see the animal.