I have had some interesting diabetic cases in the last month. Both cases were diagnosed with diabetes at other clinics and found their way to Four Lakes Veterinary Clinic. Generally, the diagnosis of diabetes is pretty straightforward. A dog or cat will be brought to the clinic because it is eating a lot, but losing weight, drinking a lot and possibly having urine accidents in the house, or looks skinny and is having problems walking or jumping. Blood and urine samples are taken to look for possible causes and, if diabetic, the blood glucose will be very high (often above 500, when the normal range is 80-120) and there will be glucose in the urine. If the pet is really sick, there may be ketones in the urine, too.
In a diabetic animal, the body isn't producing enough insulin. Insulin is the substance produced by the pancreas (an organ near the stomach) that helps glucose, a simple sugar, get into the cells of the body. Without insulin to "unlock" the door into the cell, the sugar molecules go right by. Now the body thinks it is starving, so it starts breaking down protein and fat to provide the body with glucose. But without insulin, the cells still think they are starving, even though there is now a lot of glucose in the blood stream. Extra glucose is excreted in the urine. So the blood and urine glucose levels from an untreated diabetic animal will be very high.
Once we diagnose diabetes, we start the pet on insulin injections. This insulin allows the cells to take in glucose again. Insulin produced by our pancreas is continuous and dependent on how much glucose is circulating in our blood. After a meal, more insulin is released to get the extra glucose into the cells; once the blood glucose level is normal, then no more insulin is released. But with insulin injections, the pet gets a large amount every 12 hours, generally at a meal time.
When the blood glucose is checked right before the morning insulin dose, it is at its highest level, since the previous dose of insulin has worn off. Once the insulin is injected, the blood glucose starts to drop at a fairly steady rate, with the lowest blood glucose level ideally occurring about 6 hours after the injection. Then the blood glucose starts rising again. This is called the "glucose curve" and it should be a nice bell shape.
So back to my cases. The first one was a family of two dogs, poodle brothers, that were diagnosed with diabetes at the same time. Obviously diabetes has a genetic component in dogs! They were started on insulin injections and showed improvement very quickly. But spot checks at predicted "peak insulin" times were often high, so the insulin dose was slowly increased. The owner did glucose checks at home which were often "wacky" -- there just wasn't a bell-shaped curve occurring. The dogs were feeling fine, but the insulin dose would be changed periodically based on the curves.
I saw the dogs first for a dental cleaning. We talked about their diabetes, but it seemed to be in good control at the time. The owner started sending me the glucose readings they were taking at home and the numbers just weren't making sense to me. So I had them leave the dogs at the clinic so I could do a curve over the 9-hour day.
The curve I got was not a curve at all! I suspected these dogs were getting too much insulin and exhibiting a Somogyi Effect. Remember, when insulin is present, the blood glucose level drops as the glucose goes into the cells. If there is too much insulin, almost all the glucose will go into the cells and a reading will show a very low blood glucose. But if there is still a lot of insulin in the blood stream, the body thinks it needs more sugar and will break down fat and protein to get more glucose into the blood. Now the blood glucose level is really high--if we took a reading now, it might look like the pet wasn't getting enough insulin. This is why a "spot check" of glucose is not helpful. These dogs were having their insulin dose increased, thinking they weren't getting enough, when they were actually getting too much!
I decreased the insulin dose on both dogs back to a more reasonable level. The owner noticed no changes in their drinking or appetite, which was good. If they had needed more insulin, they would have started drinking and eating more. After two weeks, I did another curve on them and it was almost perfect! One dog was a little high throughout the day and the other was a little low. So I tweaked the amount of insulin again and expect them to do very well.
My other case was a cat. This cat was seen at another veterinary clinic for a dental cleaning. Pre-anesthetic bloodwork showed a blood glucose over 500. A urine sample was obtained, which also had a lot of glucose. So the cat was diagnosed with diabetes. The interesting thing is that this cat showed NO signs of diabetes, in fact he had actually been gaining weight. Insulin was started and the cat started losing weight and not doing very well. Checks of the glucose showed he often had high glucose readings, so his insulin dose continued to be raised.
An interesting thing about cats - when they get stressed (by car rides, changes in routine, vet visits, etc), they "dump" glucose into their blood stream. This is known as "stress hyperglycemia" and I see it fairly often. But it usually only causes a glucose level around 200, not 500. But this particular cat was traveling about 20 minutes to get to the vet and really hates car rides. I don't think this cat was diabetic to begin with.
I had the owner completely stop giving the insulin and am anxious to find out how he is doing.
So while diabetes can be a very straightforward disease if the appropriate clinical signs are present and the bloodwork agrees, sometimes we can be fooled! Treatment is lifesaving for the pet, but it is very important to regulate your diabetic pet using glucose curves, rather than "spot checks." If you have any concerns about your pet's diabetes, please give us a call!
Hallmark Signs of Diabetes: