Making a diagnosis of diabetes mellitus in a cat can be frustrating. On the one hand, cats generally respond very well to treatment. Some can even be weaned off of insulin injections and eventually be managed with diet alone. On the other hand, it takes a very dedicated owner to successfully treat a diabetic cat. Insulin injections almost always have to be given twice daily, ideally as close to 12 hours apart as possible, and cats with diabetes need to be monitored closely at home and rechecked frequently as their insulin needs often change over time.
Frankly, not every owner is up to this level of care. I would rather euthanize a diabetic cat than send it home to suffer from poor (or no) regulation. Whenever I make a new diagnosis of diabetes in a feline patient, I have a candid discussion with the owner about what treatment involves. One question that usually pops up is whether or not I can predict how easy to regulate the cat in question will be. In other words, if we initiate treatment, what are the chances that it will be successful? I recently read a study that will help me better answer that question in the future.
Researchers used the medical records of 114 diabetic cats to investigate a variety of factors that could affect the length of time a cat with diabetes might survive. They found that there was a 16.7% chance that the patient died within 10 days of diagnosis. The median survival time for all of the cats was 516 days (almost 1½ years). 59% of cats lived for longer than 1 year, and 46% lived for more than 2 years.
Two factors appear to be associated with shorter survival times: high serum creatinine levels (an indicator of kidney disease) and a diagnosis of another illness in addition to diabetes. It shouldn’t be too surprising that cats that have more than one diagnosis have a harder time being successfully treated for diabetes. If diabetic management is like walking a tight rope, adding another disease into the mix is akin to walking a tightrope in a snowstorm. The relationship between increasing creatinine levels and decreasing survivability was especially strong. For every 10 ug/dl increase in creatinine the risk of dying increased by 5%.
Interestingly, the presence of ketoacidosis (a complication of severe and uncontrolled diabetes mellitus that leads to dehydration, electrolyte disturbances, and sometimes death) was not associated with a poorer prognosis. In fact, 32% of the cats with ketoacidosis survived for more than three years. This finding has to go against what many veterinarians assume: The more ketoacidotic a cat is at the time of diagnosis, the worse its prognosis must be.
My take home message is this: No matter how bad newly diabetic cats look at the time of diagnosis, their chances of enjoying another good year or two is reasonable, so long as they are not suffering from a serious concurrent disease and they have an exceptionally dedicated caretaker.
Dr. Jennifer Coates
Survival time and prognostic factors in cats with newly diagnosed diabetes mellitus: 114 cases (2000-2009). Callegari C, Mercuriali E, Hafner M, Coppola LM, Guazzetti S, Lutz TA, Reusch CE, Zini E.
J Am Vet Med Assoc. 2013 Jul 1;243(1):91-5.