My 10 1/2 year old male cat has just been diagnosed with diabetes.

He usually grazes on dry food through the day and has a wet pouch. He is on 1 unit of prozinc. I've been told not to change his food until I go back Sunday, but to only give morning and evening feedings with his insulin.

My worry is that he is a very fussy eater who doesn't readily gobble his food. Today I've encouraged him to eat before I gave the injection; he has only eaten 3g of dry food and 33g of wet food. I then gave him 5 minutes to eat more food before the injection, but he refused and left to groom himself. I then gave him his 1 unit of insulin in his scruff.

I have to go to work shortly and I'm worried whether I've done the right thing by giving the insulin without him eating much. I won't be home until 6pm. The vet is not yet open. Can someone help ease my worry? He seems okay, but I don't want to go to work as I'm worried.

  • That's really tough. I cannot answer this for sure, trying to find someone who can. When the vet does open, check about instances where the cat isn't eating much. Please let us know how you get on. I hope your cat is ok.
    – user6796
    Commented Feb 18, 2020 at 13:54
  • 1
    This isn't a good place for time-sensitive questions; there are online vets available who are better if you need an answer fast. Most of the users here are self-educated pet enthusiasts, not trained veterinarians.
    – Allison C
    Commented Feb 18, 2020 at 14:29
  • 1
    not an answer but you can heat the wet food to 35-40C to make your cat eat more,heating the food makes it smell more and the nose of cats are better than their taste buds. Commented Feb 18, 2020 at 14:32

3 Answers 3


I have spoken to my vet via the nurse and I was advised that with him being newly diagnosed, it's okay to leave some kibble in a bowl because if his blood sugar drops before I get home he would feel hungry and eat it. They said they would rather his blood sugar be up a little over him having hypoglycemia.

Tonight when I got home from work, he had eaten all the kibble and was hungry, asking me for food. The nurse also advised to give him one hour to eat his food and to try to encourage him to keep eating, then give the insulin, which I have done.

Tom ate lots more food tonight than he did this morning. I allowed him an hour in which I kept stroking and reassuring him, and he ate well. I gave him his unit of insulin, he went to groom himself, and settled down for a little snooze. He's currently acting normally.


There are 2 categories of insulin: fast-acting and slow-acting. Fast-acting insulin is mostly prescribed for humans with a bad case of diabetes and as emergency medication.

ProZinc is a slow-acting insulin specifically developed for cats. It acts over a time of 10 - 14 hours (according to the manufacturer). That means, as long as your cat eats anything at all, he should be fine.

The reason why he's supposed to eat something before the shot is probably to:

  1. Make sure he isn't ill and will refuse to eat after he got the insulin, which would definitely worsen his condition.
  2. Emulate the natural rise and fall of the insulin level in a healthy cat.

I had a look at the product information sheet and it states:

The dose should be given concurrently with or right after a meal.

Your vets might have some experience with other cats or other types of insuling that prompted them to give the advice they gave you, but your cat should be fine even if you give the shot during or right after feeding.

Since you are just starting with the insulin therapy, you should watch out for sings of hypoglycemia and probably offer him some food throughout the whole day (if you cannot be with him)

ProZinc insulin, like other drugs, may cause some side effects. Serious side effects can occur with or without warning. Please contact your veterinarian immediately if you think your cat has a medical problem or side effect from ProZinc therapy. The most common insulin-related side effect is low blood glucose (hypoglycemia). Signs of hypoglycemia may occur suddenly and can include:

  • Weakness
  • Muscle twitching
  • Depression, lethargy, sluggishness
  • Seizures
  • Staggering gait
  • Coma
  • Behavioral changes
  • Death

What actions do I take if my cat shows signs of hypoglycemia?

  • If your cat is unconscious or having a seizure, this is a medical emergency.Take your cat to the veterinarian immediately.
  • If your cat is conscious, rub approximately 1 tablespoon of corn syrup or honey on your cat’s gums. When it is able to swallow, give corn syrup or honey by mouth until your cat is alert enough to eat. Feed the usual meal and contact your veterinarian.

As with any medication, ProZinc is not free of adverse effects. Things to watch out for include:

In a 45-day effectiveness field study, 176 cats received ProZinc insulin. Hypoglycemia (defined as a blood glucose value of < 50 mg/dL) occurred in 71 of the cats at various times throughout the study. Clinical signs of hypoglycemia were generally mild in nature (described as lethargic, sluggish, weak, trembling, uncoordinated, groggy, glassy-eyed or dazed). In 17 cases, the veterinarian provided oral glucose supplementation or food as treatment. Most cases were not associated with clinical signs and received no treatment. One cat had a serious hypoglycemic event associated with stupor, lateral recumbency, hypothermia and seizures.


The following additional clinical observations or diagnoses were reported in cats during the effectiveness field study: vomiting, lethargy, diarrhea, cystitis/hematuria, upper respiratory infection, dry coat, hair loss, ocular discharge, abnormal vocalization, black stool, and rapid breathing.

If your cat doesn't want to eat, vomits or has diarhea, you should call you vet and ask if you should adapt the dosage of insulin.

And, as with all types of insulin, don't forget to mix the liquid before administration:

ProZinc insulin should be mixed by gently rolling the vial prior to withdrawing each dose from the vial.

You simply put the vial vertically between both hands and rub them gently together, like a child working putty into a snake. Never shake the vial! That introduces bubbles and can result in inaccurate dosages.


If you are worried your cat will not eat its food after being given insulin, you could consider giving your cat a carb-free food when you are at work.

I do not know the nutritional content of wet cat food, but if you give your cat some chicken or maybe some tuna, you would not need to give them insulin, because chicken and tuna are carb-free.

Both chicken and tuna can be left out for 12 hours, and will not go "bad" during that time.

If your cat does not like chicken or tuna, try finding another meat that they do like, or find a brand of wet food which does not contain carbs.

  • This is a very bad answer. Chicken can sit out two hours max: stilltasty.com/questions/index/211 Tuna is the same: stilltasty.com/fooditems/index/18558 and just "deciding" to stop giving insulin by switching food without discussing it with the vet is dangerous to the cat.
    – Allison C
    Commented Feb 25, 2020 at 14:34
  • Nadine stated in the Q that there was no time to consult a vet. For all types of diabetics (type 1, type 2, or pre), without injecting insulin or taking medication, the persons/pets blood sugar will not fall. Eating carbs w/o taking insulin or meds will cause BS to rise very high. Eating carb-free meat w/o taking insulin or meds will likely cause BS to rise slightly. Having BS rise slightly is the safest option. And cats' immune systems are stronger than humans'. The FDA "food safety" guidelines are very conservative, even for humans.
    – sam
    Commented Feb 25, 2020 at 15:24

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