Diabetes is a disorder of carbohydrate, fat, and protein metabolism, caused by a deficiency in, or a disorder of, the hormone, insulin. The deficiency of insulin results in abnormally high levels of glucose (or sugar) in the blood, for which the disease of diabetes is known.
Diabetes in cats is most similar to Type II diabetes in people, which means, that in cats, insulin is still being produced in the cat's pancreas, although the amount is inadequate. The pancreas is not responding properly to high levels of glucose (sugar) in the blood. Because insulin is still being produced, it is often possible for diabetic cats to revert to a normal non-diabetic state if it is diagnosed and treated early. Later in the course of the disease, it's less-likely to be reversible.
So, diabetes in cats is possibly reversible. This is a wonderful possibility when you start treating, and offers substantial encouragement to proceed. However, treating cats for diabetes can be very frustrating, both for the cat owner, and the veterinarian.
Dogs are relatively easy to treat. You start insulin, find a good dose, then check them in 6 months. That may be an exaggeration, but compared to cats, it's true. If you're treating a cat for diabetes, you can hope that he/she quickly responds and you can stop insulin (something that's very unlikely in dogs), but you may also be in for emergency clinic visits, hospital stays, and reports from your vet that makes it seem you'll never get it right.
It's even hard to write about. Almost everything you say about feline diabetes has exceptions and special circumstances. I think diabetic cats should be treated. It's a treatable disease, and it shouldn't be a death sentence. But, there's no getting around the fact that you must be committed enough to deal with problems and possible expense involved. If you're treating your cat for diabetes, there is a good likelihood that at some point, you will run into problems with low or high glucose levels that will require emergency attention. You should decide how far you'll go, and how capable you are. For these reasons, it's important to be informed about the disease, instead of treating blindly.
The cat's response to different types of insulin varies from cat-to-cat. Response to insulin injections can vary from day-to-day. Getting a single glucose measurement may not tell us whether the glucose was high or low just a few hours earlier. A lab test for fructosamine, which gives us a determination of how well glucose levels are controlled, will not tell us if insulin dosage is low, high or good.
Treating a diabetic cat can be very rewarding, but requires a committed owner, and some understanding of the relationship between glucose and insulin.
With this in mind, I'd like to review the interaction of insulin and glucose.
Insulin promotes the movement of glucose out of the blood and into the body's tissue cells. As the effect of insulin increases, blood glucose decreases. So, if blood glucose is higher than you want, you need to give more insulin. If blood glucose is lower than you want, you want to give higher doses of insulin.
In a diabetic cat on insulin, the owner would likely be giving an injection of insulin twice daily, about 12 hours apart. After the insulin injection is given, blood glucose levels will start to drop. The peak effect of insulin will occur hours later. How much later will depend on the type of insulin used, and the individual cat.
For example, an owner might give an injection at 8 AM. Glucose at that time may be high. At 11 AM, blood glucose may be in the normal range. By 1 PM, glucose levels may again be rising. By 8 PM, blood glucose levels are high again. The time of day that glucose is at it's lowest will vary on the type of insulin and the individual cat.
Let's look at this example again. If the cat's blood glucose is high from 8 AM to 10 AM, normal from 11 AM to 12 PM, and then high from 1 PM to 8 PM, then blood glucose control is not great. Glucose is high most of the day. If this were a person, his/her physician would not be happy with the results. However, increasing the insulin dose is not likely to increase the length of time that glucose is normal. It more likely will cause the glucose to drop too low before 12 PM, and possibly precipitate a low blood glucose episode that may need emergency attention.
So, if you can't change the insulin dose to help this cat's control, what can you do? Well, in most cases, if the symptoms are acceptable at this point, we'd most likely leave it as is. If the symptoms are unacceptable, such as urinating frequently around the house, the choices would be to try another type of insulin, possibly multiple types of insulin, or increase the frequency of injections.
Well, if you made it this far, and you understand it, you're in pretty good shape. Everything that follows deals with individual circumstances and problems.
Let's say in the example above, while regulating the cat with your vet, you tested the glucose just at 8 AM and 1PM. Well, each time you tested, the glucose would be high, even though the level was normal about 10 AM,and your vet might tell you to increase the insulin dose. In no time at all, you'll have a cat with dangerously low blood glucose, and he/she will probably end up at the emergency clinic. And, what will you find when you get home to the cat with low blood sugar, a cat seizuring.
I mentioned fructosamine. Fructosamine is a protein in the blood that interacts with glucose, and can be measured. It gives us an indication of whether glucose has been low, normal or high over the entire period of time 2 weeks previous to testing. If we tested our cat in the example above, the results would be high, because for most of the day, for every day in the past 2 weeks, the glucose was high. If the insulin dose is increased based on this, you've got your hypoglycemic (low blood sugar), seizuring cat again.
So what happens if you're giving too much insulin to a cat. Remarkably, after the blood glucose goes too low, it may immediately bounce back to a very high level. Let's say in our example above we were giving too much insulin, and at 10:00 the blood glucose was too low, but not low enough to cause seizures. Well, at 12:00, the blood glucose may bounce back and go even higher than it would have. A measurement taken at that time might indicate that more insulin was needed, and the result is your seizuring cat again.
Now another situation. Your cat became hyoglycemic and seizured, and went to the emergency clinic. Your cat's blood glucose may remain low for weeks, and you might not need to give insulin for awhile.
Veterinarians will tell you not to give insulin if your cat doesn't eat. The reason for that, is that if they're not eating, they don't need as much insulin, and giving the regular insulin dose could result in hypoglycemia. Well guess what. What happens when the diabetes is not under control and the blood glucose is high for so long that your cat becomes sick? -- they stop eating. So guess what happens if you stop insulin? -- they get sicker, and you're back at the emergency clinic. If your cat stops eating, don't just stop insulin. You need to find out what there blood glucose is. One good thing for the committed owner, blood glucose can be measured at home.
Just a few notes about insulin types. Not every cat reacts to each type of insulin the same way. Some cats have problems absorbing some insulins.
Idexx PZI insulin has been frequently used in cats. It is a beef-pork insulin product. Beef insulin is closer to the cat's natural insulin than pork or human insulin, and as far as I know, it's the only beef insulin product. It requires special syringes.
Vetsulin is a pork insulin product that uses the same syringes. Some veterinarians mistakenly use this product interchangeably with Idexx-PZI insulin, but that is a mistake. The products are not interchangeable.
Human glargine insulin is currently popular for treating cats. This is a long-acting insulin that requires knowledge of both the lowest point that the blood glucose reaches, and how long the affect of one shot is.
We now know that dietary change can significantly affect the diabetic cats response to treatment, and early-on may be a factor in eliminating the need for insulin. I didn't mention these diets earlier in the text, because I don't want the owner of a newly diagnosed diabetic cat to think they can just change the cat's diet and everything will be better. You still should be starting insulin along with the dietary change. Prescription low carbohydrate, high protein diets are used.
Non-injectable drugs are also used occasionally instaed of insulin. Response to these drugs are occasionally, but not frequently, seen, and may only delay the need to start insulin. Frankly, I wouldn't use these medications unless a cat owner absolutely refused to give insulin injections.
Last thing. Underlying disease can frequently complicate diabetes. Some of these diseases are common infections that diabetics are more susceptible to. Others are hard to diagnose, seemingly unrelated illnesses, that can make diabetes difficult to control. I have also seen cancers that caused diabetes (hyperglycemia), that in later stages caused low blood sugar.
I hope I haven't convinced you not to treat your diabetic cat, but I feel you should have some idea of what to expect. At the Animal Emergency Clinic, I've seen too many cat owners that were lost, and had no idea what they were getting into.
If you have or had a diabetic cat, and wish to share your experience good or bad, please send it to yourpetdoc@aol.com. I'll post these experiences on a link from this web page.
