Diabetes in cats

What is diabetes ?

This disease occurs when there has been too much sugar (glucose) in the cat's blood for some time.

This rise in sugar happens either because the pancreas produces less insulin (type I diabetes) or because insulin is unable to bring glucose into the cells of the body's organs (type II diabetes).

Cats are more likely to have type II diabetes.

The result is the same regardless of the reason: glucose can not be used by the organs as a source of energy.

Clinical signs of diabetes

  • Weight loss despite a normal or increased appetite;
  • An increase in the amount of urine;
  • An increase in thirst;
  • Bacterial infections, especially of the skin and / or urine;
  • Muscular weakness that causes the cat to "walk on his heels" and have difficulty jumping or climbing.

Cats that are affected by this type of diabetes, also known as "uncomplicated" diabetes, often do not look sick.

However, sometimes diabetes becomes "complicated" when ketone bodies accumulate in the animal's blood. These ketone bodies are toxins that poison it.

We then see the following symptoms appear:

  • Loss of appetite,
  • Depression,
  • Dehydration,
  • Vomiting.

The accumulation of ketone bodies can even cause the death of the animal.

How is diabetes treated ?

The best way to control the animal's diabetes is to inject insulin to get the glucose into the cells.

In addition, it is recommended to feed the animal with a "diabetic" diet prescribed by a veterinarian, which contains a lot of protein and little carbohydrates.

The combination of this food with insulin injections can sometimes cause a remission of diabetes and the disappearance of symptoms. A remission is usually more easily achieved when diabetes is diagnosed soon after onset.

When remission occurs, insulin can usually be stopped. However, it is necessary to continue the special food for the remainder of the cat's life to reduce the risk that the diabetes returns. Indeed, if the cat is allowed to eat a regular diet then diabetes tends to return in less than a month in 95% of cases. Fortunately, a second remission is still possible if the diabetic diet and insulin treatment are reinstated.

Can insulin cause side effects ?

Insulin can lower the animal’s blood sugar to a level that can be dangerous (hypoglycemia). This happens especially when the dose of insulin is too high, for example if the cat is in remission or if one makes a dosage error. 

Symptoms to watch for are the following: 

  • depression and weakness; 
  • a faltering step; dizziness; 
  • stiffness; 
  • seizures, coma and possibly death in severe cases.

Ideally, the blood glucose level should be measured with a glucometer, if you have one, when you observe such symptoms in the animal to confirm that they are actually caused by a drop in blood glucose. 

If the glucose level is indeed very low then you can make the animal drink 1 tablespoon of corn or maple syrup or apply it on his gums.  

If you don’t have a glucometer, it is still advisable to give him the syrup.  

Afterwards, you will need to contact a veterinarian immediately to find out what to do from there.

Are there different types of insulin available ?

Yes. There are mainly two types of insulin used for cats: glargine (LantusÒ) and ProZincÒ.

The difference between them is mainly in the speed with which they begin to act and how long their effect lasts. 

In general, cats need 2 injections per day at 12-hour intervals. (eg if insulin is given at 8am then the second dose should be given at 8pm).

What are the other treatment options ?

There are also hypoglycemic tablets (eg Glyburide) that cats can take by mouth to try to lower their level of glucose in the blood. 

It is not clear how they work, but it appears that they increase insulin production by the pancreas and improve the insulin effect in the organs. 

Oral hypoglycemic agents are generally much less effective than insulin in treating type II diabetes. Moreover, they can not be counted on to hope for a remission and they do not work for type 1 diabetes. 

Another reason that it is best to treat diabetes with insulin instead of with oral hypoglycemic agents is that they can cause several side effects (eg, vomiting, liver damage, depression, loss of appetite, etc.). and that they are contra-indicated in several cases. 

When there are other illnesses present at the same time as the diabetes, it is important to treat them also (eg, urinary tract, dental or skin infection, etc.) because they can cause insulin resistance and prevent the treatment for diabetes from working well.

How does the cat's weight affect the control of his diabetes ?

Obesity promotes the development of diabetes. In addition, it impairs the control of the disease because it also decreases the effectiveness of insulin. That is why it is necessary to prevent your animal from gaining too much weight and becoming obese. If he already is obese, then he must lose weight and, once he has reached his optimal weight, he must also maintain it. 

One can increase the animal’s level of physical activity and feed him the diabetic diet to help him lose weight. It is important to measure exactly how much food the cat can eat during the day and not give more food than the amount permitted. 

The calculated amount is divided into two meals a day. We wait about 30 minutes after he has eaten and then insulin is injected. 

However, if the animal prefers to eat small amounts of food throughout the day, it can continue to be fed in this way.

What is fructosamine ?

Fructosamine is a protein that binds to excess glucose in the blood. Its level increases when the level of glucose in the blood has been too high for more than 6 to 12 hours.  

The measurement of fructosamine indicates the mean level of blood glucose for the last 2-3 weeks.

Why measure fructosamine ?

Measuring fructosamine is therefore a way of distinguishing between a blood glucose level that is too high because of the stress of the visit or because of the diabetes. Indeed, if the level of fructosamine is too high then it means that it has been at least 2-3 weeks that the glucose level is too high. It is therefore concluded that diabetes is the cause of this excessively high glucose and not stress. 

We can also measure fructosamine to see if diabetes is under control or not, if the blood glucose curves can not be done at home. However, this option is not ideal for different reasons. 

First, because the amount of glucose can vary a lot in the same day. This may cause the mean value of fructosamine to remain normal, even if the blood glucose level is high for long periods. 

Secondly, it is only when the rise of glucose exceeds a certain level that fructosamine increases. Consequently, we might miss the beginning of diabetes in some cats if we rely only on the measurement of fructosamine. Indeed, the level of glucose is generally not that high when the disease starts. 

Finally, although the measurement of fructosamine can be used to show that there has been a loss of control of diabetes, it can not explain why this loss of control has occurred. It is only with a blood glucose curve that we can identify if it is the dose of insulin or the duration of it’s effect that is no longer adequate.

Treatment monitoring

When we start the treatment, we will want to monitor the blood glucose level of the cat closely. The goal is to check that the prescribed dose of insulin is effective and also to make sure that the glucose level does not get too low. 

Generally, it takes about 10-14 days for the glucose level to stabilize. We will want to do what is called a "blood glucose curve" at that time. It means measuring the level of glucose a few times during the day.  

It is best to do the blood glucose curve at home to prevent the stress of hospitalization from raising the blood glucose level of the cat. A glucometer designed specifically for animals (eg. AlphaTRAK2®) must be used because human glucometers are not calibrated for animals and could provide false numbers. 

If the curve is done at home, it will be necessary for you to transmit the results to the veterinarian in charge of the animal so that he or she can analyze them and determine if the insulin dose needs to be changed or not.  

The blood glucose curve is the only reliable way to know if the diabetes is controlled adequately. Indeed, the glucose level may still be too high even if the symptoms have disappeared. This needs to be avoided because when there is too much glucose in the blood for a long time, it can damage the pancreatic cells that make insulin. In addition, it can also reduce the effectiveness of insulin in organs. 

Thereafter, the frequency of the blood glucose curves will vary depending on whether the diabetes is under control or not. As a general rule, curves should be done 10-14 days after each insulin dose change. Also, blood and urine tests are recommended every 6 months.

How to handle insulin ?

To conclude, here are some tips to follow regarding the storage and handling of the insulin vial:  

  • Keep the vial in the refrigerator. The product can be kept for a few months (depending on the type of insulin prescribed) as long as the bottle remains clean;
  • Mix the product well by inverting the vial a few times (do not brew it);
  • When inserting the needle into the vial and pulling the plunger, an air bubble will enter the syringe at the same time as the product. This air bubble must be expelled by "flicking" the end of the syringe;
  • Before injecting the product into the cat, first take a pinch of skin on the side of his chest and lift it to make a small tent;
  • Then, insert the needle at the base of the tent and push the plunger. Make sure that the syringe is snug against the skin before injecting. The needle should move freely if it is well positioned under the skin and not in its thickness;
  • It is necessary to change syringes and alternate the sites of injection.

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