Diabetes Mellitus Part 2

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.