Living with a diabetic cat

Cats can cope well with diabetes. With help from its human a daibetic cat can still lead a long happy life. It is understandable that some people might be frightened by the prospect of a cat needing medication twice daily and medication with a needle atthat. At present there is no cure for diabetes, but with a well-managed diet, some cats may lose the need for insulin over time. As mentioned in other articles in this section, diabetes comes in two forms, type I and type II. If an obese cat has type II diabetes, slimming her down can work wonders, and once their weight is sorted out some cats can go into permanent remission (that is, the diabetes seems 'cured'). The news is not so good with type I diabetes, and if a cat suffers from this, it will probaby require insulin for the rest of her life.

If your cat is first diagnosed with diabetes, and the vet decides that she needs insulin injections, the cat will have to be monitored for at least 24 hours and regularly tested for blood glucose to determine what insulin dose is suitable. But in any case, the first dose is always only provisional, and it will need to be adjusted with time to get best results. The normal procedure at the start is to give a lower than required shot of insulin and increase this slowly over time. It is dangerous to give too much insulin because of the risk of hypoglycemia or Somogyi Rebound (see below).

The cat's level of blood glucose will need to be tested regularly. You can do this at home. Here is an excellent video showing home testing:

Guidelines to blood sugar level:(note that these are given in mmol/l and mg/dl (the scale used in the USA))

  1. normal non-diabetic range: 2.2-7.5 mmol/l or 40-130 mg/dl
  2. acceptable range for diabetic cats: 5.5-10 mmol/l or 100-180 mg/dl
  3. level when symptoms become obvious: 10-15 mmol/l or 180-270 mg/dl

The important thing with diabetic cats is to keep them within the acceptable diabetic range. Aim for the lower level. At the high level of 10 mmol/l some cats will be visibly ill. More than 15 mmol/l and the cat will be dangerously hyperglycemic. If you see such a high reading, make sure you also check for ketons in the blood.


A hypoglycemic episode (a sharp lowering of the blood sugar level) can happen even with very careful monitoring. It can happen through a change of insulin dosage or a different type of insulin used. But it can also happen unexpectedly, because a cat's insulin requirement can change. Hypoglycemic cats are very lethargic, and suffer spells of dizziness. They may also start vomiting or having seizures. If this happens it is very important that the glucose levels are raised as fast as possible. Give the cat some honey and if she can't or won't eat that, rub some honey on her lips. Take the to the vet immediately, but keep giving her honey all the time, since this may actually save her life.

Somogyi rebound

Somogyi rebound happens when the body itself starts to regulate its glucose level by releasing glucose from cells to protect itself against hypoglycemia. What normally happens is that if the glucose in the blood drops to a critically low level(normally less than 2.2 mmol/l)a hormone known as glucagon (produced in the pancreas) is rapidly released. Glucagon is the opposite of insulin. It works by stimulating cells to release glucose (cells have special mechanisms to store certain vital compounds in special places known as stores; so for example they have calcium stores and glucose stores. Compounds within the stores are not used unless the body needs them quickly to restore its chemical balance. So with a Somogyi rebound the body quickly empties the glucose stores of the cells to protect itself from hypoglycemia. This raises the glucose level in the bloodd, sometimes to a high level. A readout of the blood sugar at this point it will record hyperglycemia. You might react by giving a shot of insulin, which is actually the last thing you should do. Despite the high glucose reading, the cat is actually hypoglycemic (in need of glucose) and once the glucose stores from the cells are exhausted the level of glucose in the blood will nosedive, even without insulin speeding up the process.

In diabetic cats the Somogyi rebound can happen when too much insulin is used. Therefore despite appearances the correct response is to lower the level of insulin. The Somogyi rebound may also occur when a cat's blood glucose drops too rapidly, even if it never actually reaches a low level - the cat's body thinks it is heading there, and reacts accordingly.

If is often difficult to diagnose a Somogyi rebound. One way is to monitor blood glucose for 24 hours, taking reading every 2 hours after an insulin injection. When you plot the graph you should see a decrease in glucose levels for the first 6 hours followed by a slow increase which levels down again after 16 to 18 hours. With a Somogyi rebound there is a much sharper fall and rise of blood glucose. Another usful sign is apparent unresponsiveness to insulin for a couple of days.

If you think your cat has had a Somogyi rebound, lower the dose of insulin and take the cat to the vet.

Note: This information is for guidance only. It is not intended to replace consultation with a licensed practitioner.

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