Did Steroids Cause My Cat’s Diabetes?


In this very special Halloween edition of my column I am answering two questions.

Help! There are phantom poops in my cat’s litter box! What should I do? Thanks, Joe.

Get a Labrador Retriever and tell him they’re phantom Snickers bars.

My 11-year old cat has gotten Depo Medrol shots for allergies for some time now, and is newly diagnosed with diabetes. My vet is unaware of a connection between the two. Going this afternoon to learn to give insulin shots. My question is, if she stops getting the Depo Medrol, what do we do about her allergies? Will we possibly be able to change her diet and eventually not use insulin?

Thanks so much,


Eating too much Halloween candy is a common cause of diabetes in people but not cats. Steroids, on the other hand, can be linked to diabetes in feline companions.

Depo Medrol is a long-lasting injectable steroid that is commonly used in cats. It is related to and works similarly to prednisolone. Depo Medrol and prednisone are cortisone analogues. They modulate the activity of the immune system, which is why they work so well for allergies.

For many (although not all) cats, the first injection of Depo Medrol will have seemingly miraculous results. Allergy symptoms resolve. Overgrooming may stop. Signs of arthritis may disappear. But, after a few weeks, the medicine wears off. Most cat owners return to the vet for another round of the miracle therapy, but most of them end up chasing the metaphorical dragon.

Over time, with repeated injections, the effects of Depo Medrol become less miraculous. Simultaneously, the side effects become an every greater menace.

What are those side effects? Steroids can be linked to increased thirst and urination, increased appetite, behavior changes, and weight gain. Cortisone and its analogues also have an effect on blood sugar — they make it go higher. Therefore, some cats who receive enough Depo Medrol will develop diabetes mellitus (also known simply as diabetes) as a side effect. (And let’s not even go into the issues that might occur in cats receiving Depo Medrol produced at the New England Compounding Center!)

Mary, it is not certain that the Depo Medrol caused your cat’s diabetes all on its own. But the medicine certainly isn’t going to help the situation. And you should be aware that many cats who develop diabetes as a complication of Depo Medrol may revert to a non-diabetic state after the medication is withdrawn. Even if your cat is not one of them, you should be aware that continuing the Depo Medrol injections will make regulating your cat’s diabetes very difficult or perhaps impossible.

I therefore recommend that you talk to your vet about elimination of steroids from your cat’s allergy treatment regimen. Go back to the basics to treat the allergies: Use appropriate flea control. Consider switching to a novel protein (hypoallergenic) diet. See a veterinary dermatologist to talk about other non-steroid treatments for allergies. If your cat’s allergies can’t be controlled without steroids, talk to your vet about oral steroids at very low doses that won’t lead to big intermittent steroid surges like Depo Medrol provides. Those steroid surges will make controlling the diabetes really difficult.

If things go perfectly, you can discontinue all steroids (they may need to be tapered to prevent withdrawals) and control the allergies with the tricks above. After the steroids are out of your cat’s system, she may revert to a non-diabetic state. It may not work out this way, but in my opinion, this is a much better goal than continuing the steroids and adding insulin as well.

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