Stress hyperglycemia

An elevated blood sugar doesn't always mean there’s a problem.


When Cata’s owner passed away last year, the elderly kitty was adopted by Good Samaritan One, who soon noticed she was losing weight. Maybe Cata was grieving the loss of her original owner. Perhaps she was simply growing frailer with age, as older kitties sometimes do. But there are also illnesses that can cause weight loss in that demographic, such as hyperthyroidism, kidney failure, diabetes, cancer, or heart disease. We advised blood tests to rule out some of these. Cata’s results looked basically normal, except her blood glucose (sugar) was slightly elevated. To give you a frame of reference, normal feline blood glucose runs between 70 and 150 mg/dL. Cata’s was 202 mg/dL. We weren’t too concerned by that. Why not? Because cats, being cats, have a unique reaction to acute stress. It can make their blood sugar shoot up significantly above normal. To 200 or even higher. Not every cat. Not every time. But veterinarians know that in a stressed cat, an elevated blood sugar doesn’t always mean there’s a problem. On the other hand, once that blood glucose gets to 300 or higher, it’s highly likely that cat has diabetes.

Whoa. Let’s back up a minute for a brief endocrinology lesson. Diabetes mellitus is a condition in which the pancreas produces inadequate insulin, the hormone necessary to move glucose from the blood into the cells where it is needed for fuel. Without insulin, blood sugar goes way up, but the body can’t utilize it. The patient gets hungry and thirsty, but loses weight. That’s the simplified version. There are all kinds of details about Type I versus Type II, and how diabetes is different in cats versus dogs versus people, but today’s takeaway is that a moderately elevated blood sugar in a stressed cat does not necessarily mean diabetes.

Except Cata did have diabetes. We just didn’t know it yet. Several months later her symptoms had progressed. It’s difficult to ask an owner to repeat tests they have already paid for once, but the reality is, that may be what’s needed to make a diagnosis. Eating also raises blood sugar, so this time we had the owner fast Cata for 12 hours, then we drew blood with as little stress as possible. This time her blood glucose was 376 mg/dL. In retrospect, it is possible that the earlier mildly elevated glucose level might not have been just from stress. It might have been a harbinger of things to come. Now, however, her blood sugar was so high there was no question that this was truly diabetes.

The great thing about diabetic cats is that if you switch to the right diet and start insulin injections immediately, a significant percentage will go into remission within a few months. That means the diabetes will resolve. Some relapse eventually, but others can be controlled just with appropriate diet and weight management. Good Samaritan One didn’t feel comfortable managing a frail, elderly, diabetic cat needing twice-daily shots. Totally understandable. Happily, Good Samaritan Two, a medical professional, stepped up and offered to take over. Cata went to another new home, where she is doing well.

Not long after Cata left, Caspar the cat arrived. Poor Caspar. He had been a stray for who knows how long. Someone had been feeding him, and during that brutal cold snap, took him into her house, and noticed he wasn’t eating. She called the animal control officer, who brought him to us to evaluate. Caspar was looking bad. Really bad. Thin as a rail. Yellow pus pouring from his nose and eyes, which he could barely open. Face encrusted with dried goo. Coat caked with massive amounts of flea dirt. Dehydrated. Hypothermic. Fecal matter matted under his tail. Fur stained with urine. “Doesn’t look good, ” I said, stating the obvious. But I have seen cats come back from worse. This could all just have been from neglect, exposure, and parasites, with secondary infections. “Let’s run some tests,” I said. “If he has something life-threatening, like feline leukemia virus, or advanced kidney failure, we should probably call it quits right now,” I added reluctantly. I’m a sucker for hopeless cases.

Caspar was so cold and dehydrated I couldn’t get a blood sample at first. We began supportive care. Fluids, hot water bottles, antibiotics, flea control. When we finally got a blood sample, our tests revealed many minor abnormalities, but they could all be attributed to his extreme debilitation. His blood glucose was 270 mg/dL. Well, I thought, not surprising considering how stressed he is. Except Caspar was diabetic. I just didn’t know it yet.

Over the next week, we continued to treat Caspar with antibiotics and supportive care. By day four he was eating, and had gone from six pounds to seven. His ocular and nasal discharge had almost completely resolved. He was shy but not wild. “We can send him to the shelter soon,” I concluded, “but let’s just double-check that blood glucose before he goes.” You can see where this is headed, right? His fasted, nonstressed blood glucose was 324 mg/dL. Caspar was diabetic. (What I said next can’t go into the paper.) Now what? Caspar had a microchip which enabled us to determine he is around 11 years old, but no one has claimed official ownership. The animal control officer wanted to help, and I hated to give up on Caspar, considering how far he had already come.

This morning we started Caspar on insulin. His blood sugar this afternoon was a lovely 109. Now we just have to see if he stabilizes well, like Cata did. If he does, he’ll need a real home soon. Maybe another good Samaritan will read this and volunteer to adopt Caspar. If you are willing to give tiny insulin injections twice daily (it’s really easy, don’t be intimidated), and to work with a cat who may be a little shy, but who has been through an awful lot and survived, contact the Tisbury ACO at 508-696-4209.