Overview:

Diabetes Mellitus ("sugar" diabetes) is a common endocrine disorder in cats. There are two types of diabetes, type 1 in which the pancreas doesn't produce enough insulin or type two in which the body's cells don't respond appropriately to insulin.

Insulin is a hormone produced by the pancreatic islet cells. When a cat eats, food is broken down into organic compounds, one of which is glucose. Glucose is taken up by the cells for energy, growth & repair.

When the cat eats, the pancreas should produce the right amount of insulin, which attaches to the cell walls & enables the glucose to move into the cells.  In the diabetic cat, because the quality or activity is decreased, the body tissues cannot use glucose.  The glucose accumulates in the bloodstream causing  the cat to develop hyperglycaemia (high blood sugar) & subsequent glucosuria (sugar in the urine).

What happens in the diabetic cat?

Diabetes has many effects on the cat's body.

Because the glucose is unable to enter the cells, the body is starved of energy & the cat begins to lose weight, despite having a healthy appetite. If the diabetes goes untreated the body will begin to break down the body's own fat & protein to use as energy, leading to weight loss.  Ketones in the urine & blood are a by-product of the body's digestion of it's own tissues to produce energy. The presence of ketones in blood or urine are a sign the disease has progressed. Ketoacidosis is a serious complication & requires immediate veterinary attention.

High glucose levels in the blood cause the cells begin to malfunction due to lack of glucose, and are unable to reproduce themselves when their life span is complete.

The kidneys try to remove the glucose from the blood, and high levels of urine are produced, which causes excess thirst in the cat. This is known as polydipsia (PD). Due to the higher workload on the kidneys they are often the first organs to show signs of damage.

High blood sugar also has a damaging effect on the tiny blood vessels which nourish the retina. This is known as diabetic retinopathy & can lead to mild vision problems to blindness.

Weakness in legs (neuropathy).  Nerve cells are also susceptible to high glucose levels in the blood. Nerve, eye & kidney cells do not require insulin to take up glucose so in the diabetic cat they may take in high levels of glucose. Weakness in the legs is caused by this nerve damage.

The earlier diabetes is detected, the less time the disease has had to damage the cat's body, so it is important to seek veterinary attention as soon as you see any changes in your cat.

What are the symptoms of feline diabetes?

Symptoms of diabetes include:

What causes feline diabetes?

Nobody knows the exact cause of diabetes yet. There are several reasons a cat may become diabetic. Genetic predisposition, obesity can cause insulin resistance, previous  diseases such as Cushings Disease, hyperthyroidism & pancreatitis. Some medications (steroids)  may also  play a role.

How is feline diabetes diagnosed?

Diagnosis is based on the signs the cat is displaying. A physical examination from your vet may indicate diabetes. Enlarged liver (hepatomegaly) due to lipid accumulation, weight loss, poor coat, dehydration can all point to diabetes (but may be caused by other diseases also).

Diagnosis based on a single blood test may prove inaccurate as it is possible for the blood to show elevated glucose levels as a result of stress (transient hyperglycaemia). Therefore a diagnosis based on a single blood & or urine test can not give a definite diagnosis of diabetes. There are several solutions to this. Perform several blood & urine tests over time. Try to collect a urine sample from home, when the cat is not stressed.

Measuring levels of fructosamine in the blood is another method to test for diabetes. Fructosamine is formed when albumin and glucose react together irreversibly and gives an idea of average blood glucose over the preceding 1-2 weeks. Reduced total protein and hyperthyroidism can cause a decrease in the result. Chronic stress can cause a small increase but not usually into the same range as diabetes.

The presence of ketones in the urine indicate the disease has progressed.

Which cats are at risk of feline diabetes?

Diabetes can affect any cat, of any age, breed or gender. However, it is seen more often in obese & or middle aged to older cats. Male cats are affected more often than female cats.

How is feline diabetes treated?

There are possible regimes for the diabetic cat. Depending on the severity of the disease.

In mild cases, the cat may be managed with diet alone. If the cat is not ill, and has no ketones it may be possible to manage diabetes without the use of insulin. This may include dietary modification & or careful weight loss, under the careful guide of your veterinarian.

Oral hypoglycaemic drugs (glipizide) may also be prescribed.  The exact mechanism of glipizide isn't known but it is believed that it stimulates  the pancreas to release insulin.

Monitoring: Even though the diabetes may be mild, careful monitoring of the cat is vital. If they become unwell, develop ketones or remain persistently hyperglycaemic then the next step will be insulin.

Insulin: This involves the injection of insulin once or twice a day. It is administered subcutaneously (under the skin), at the scruff of the neck. These can be given at home, usually at the same times daily. Individual cats respond differently to insulin, and may need to be adjusted based on blood glucose profiles, clinical response & urine glucose monitoring.

Hypoglycemia (low blood sugar) is a potentially dangerous complication of insulin therapy. This is caused by either too much insulin or the cat not eating enough food. The cat's blood sugar levels dip dangerously low. Feeding small but frequent meals will help avoid this condition but careful monitoring of your cat's blood sugar levels is important. Signs of Hypoglycemia include weakness, listlessness, lethargy, wobbly gait, convulsions & coma. If left untreated it can lead to death. If you notice any of these signs in the diabetic cat you should offer it some food to eat. If this is not possible, rub a tablespoon of corn syrup onto it's gums. Do NOT force fluid or liquids down the mouth, and keep your fingers be placed inside the mouth of a cat having convulsions or in a comatose state. You should notify your veterinarian immediately so that the insulin dose can be re-adjusted.

Prognosis:

If properly managed a diabetic cat can live for many years. In some cases diabetes has resolved itself in time. It is important to regularly monitor your cat & work closely with your veterinarian.