Feline Diabetes: My Advice for Diabetic Cats [en]

After 2.5 years of dealing daily with feline diabetes (and over two years of managing a French support group), I thought I’d put together an English version of what my best advice for diabetic cat owners is so far, as most of what I’ve written on the subject is in French.

Things to know

I’m starting with this as a sort of FAQ/TL;DR:

  • upto 84% of remissions within six months of diagnosis using Lantus/Levemir and home monitoring (injections do not have to be for life)
  • Lantus/Levemir are far superior to Caninsulin/Prozinc
  • home monitoring makes a huge difference in quality of regulation and reduction of risks, as well as chances of remission
  • a diabetic cat can be well-regulated and lead a normal life
  • FreeStyle Libre continuous glucose monitors can be used successfully on cats
  • a normal human glucose meter can be used for monitoring, pet meters to not add significant value to the monitoring
  • diabetic ketoacidosis kills more cats than hypoglycemia – at a bare minimum have urine dipsticks to monitor ketones in urine
  • inject twice a day at regular times, and prefer syringes over pens (you can draw insulin from the pen with the syringe)
  • inject a constant dose of insulin (no fiddling with the dose at each injection), and adjust the dose progressively according to the lowest glucose value reached with the previous dose
  • a decently regulated diabetic cat can miss a dose of insulin now and again if necessary
  • a diabetic cat can be fed wet, dry, raw, whatever you want; less carbs and more protein is good, therapeutic “vet” diets are fine; free-feeding dry therapeutic food has huge advantages with Lantus/Levemir
  • never change a cat’s diet without close monitoring if it is under insulin

Getting started

If your cat has just been diagnosed, you’re probably in shock and afraid to lose him or her. The first thing I’d like to tell you is that feline diabetes is a very manageable disease, and that there is no reason for a well-managed diabetic cat to die from diabetes.

The second is that the treatment for diabetes is insulin injections (no way around that), and you will get over your fear of doing them if that is an issue for you. And it does not have to be “for life”. A 2009 study has shown that with the right treatment protocol (Lantus/Levemir insulin and serious home monitoring), upto 84% of newly diagnosed cats (less than six months since diagnosis) could achieve remission. Remission means the diabetic cat doesn’t need insulin injections anymore.

I have seen cats in critical condition upon diagnosis, skin on bones or diabetic ketoacidosis (more on that later), with other illnesses, go on to not only survive but thrive and reach remission. It’s work, of course, but it’s worth it. I have seen owners who were panicked by needles and blood go on to not only give insulin injections without a second thought, but also monitor blood glucose at home multiple times a day, with a little blood prick on the edge of the ear (the cat usually minds way less than the human doing it!)

A well-managed diabetic cat can have normal quality of life and live out the rest of his cat years with no major consequences.


Insulin is a hormone secreted by the pancreas. Its job in the body is to make glucose from the bloodstream enter the cells (glucose is fuel/energy for the cells). Diabetes is due to an issue either in insulin production (poor pancreas is sick or damaged and can’t do its job correctly), or what is called “insulin resistance”, meaning that something in the body prevents the insulin from doing its job correctly. The insulin is there but it can’t get the glucose into the cells. This insulin resistance then exhausts the pancreas as it tries to keep up, in vain. Common causes of insulin resistance are obesity, illnesses like acromegaly, or (note the vicious circle) high blood glucose.

To manage diabetes, we are going to give the body extra insulin to help it along and help feed the cells. Insulin is a fragile molecule, and it doesn’t survive going through the stomach, so it has to be injected. The needles used to inject insulin just under the skin are tiny, and cats barely feel the injection once you get the hang of it.

There are four different insulins that are commonly prescribed for cats: Levemir, Lantus, Prozinc and Caninsulin (called Vetsulin in the US). Levemir and Lantus give by far much better results than Prozinc or Caninsulin. With them, cats are easier to regulate, get a better quality regulation, and a higher chance of remission. Remission and correct regulation are possible with Prozinc and Caninsulin, but less likely and more tricky. On the French group, we often help owners discuss switching insulins (French document) with their vet.

If you can get Levemir or Lantus, go for it. Prozinc is better than Caninsulin, but Lantus and Levemir are in a whole other category. If you have a human insulin like NPH or Insulatard, it’s going to behave similarly to Caninsulin. Tresiba (a new, long-lasting human insulin) seems to behave like Lantus and Levemir.

Whatever insulin you are using, you want to inject twice a day, 12 hours apart. With Lantus or Levemir, it’s really 12 hours – give or take 15 minutes. With Caninsulin and Prozinc there is more flexibility (even a couple of hours), but you’ll get better results with regular injection times.

You also want to inject the same dose of insulin continuously. Varying doses or skipping injections regularly make regulation difficult. The best dosing methods involve injecting the same dose of insulin for some time, then evaluating how that dose is performing through blood glucose measurements, and then adjusting the dose by a small increment, and reevaluating again, and so on.

Using syringes rather than pens allows for more precise dosing and also makes the injection itself faster for the cat.

Home monitoring

Home monitoring is the key to managing diabetes well. It’s even more important than the choice of insulin. With a glucose meter, you can easily check your cat’s blood glucose. Regular measurements will help keep your cat safe (both from hypoglycemia and from the consequences of bad regulation) and give you precious information to adjust the insulin dose (with instructions from your vet or by following a time-tested dosing protocol). This will give your cat the maximum chance of remission and, even if you don’t reach remission, the best regulation possible, and therefore the best quality of life and health.

If you can, I highly recommend using a FreeStyle Libre continuous glucose monitor for your cat. The monitor is attached to the cat’s skin with a sticker. It lasts upto 14 days and each time you scan it (with your cellphone or a dedicated reader) you get the last 8 hours of readings (4 readings per hour). This means you never miss any information on how the blood glucose is evolving, and you can relax about when to check it. It’s also a great solution if you’re away from home a lot, need to board your cat or have somebody looking after him or her that cannot do “ear prick” tests, or if your cat is hard to test (I’ve had one, I know some cats can be impossible). Here is a video demonstrating how to apply the FreeStyle Libre sensor, and providing some explanations. (See on Facebook.) Many owners apply the sensor themselves at home.

One thing you should absolutely be monitoring, whether you monitor glucose or not, is ketones. An unregulated diabetic cat can develop ketones (if his cells are starving so much that he starts metabolising fats to get energy). Ketones accumulate in the blood and the cat ends up developing diabetic ketoacidosis, a deadly complication. Cats with DKA (diabetic ketoacidosis) can be treated and saved, but in my experience many vets are not equipped to manage it, as it requires 24/7 intensive care for a number of days. I have seen way more cats die from ketones and DKA than from hypoglycemia.

Keeping an eye open for early traces of ketones is therefore absolutely necessary, both for your cat’s life and your bank account. It can be done in two ways: either with a glucose meter which also measures ketones, or with urine dipsticks (photo below). If you’re not monitoring blood glucose, get the urine sticks. They have colour codes which will also tell you how much glucose is in the urine, a precious indication if you’re not monitoring blood glucose. If you are monitoring blood glucose, then a meter is a better choice, because it is more precise, and you do not need to wait for the cat to pee. If your cat has already had ketones or DKA, she or he has a one in three chance of developing ketones again. In that case too, you really should have a meter. (Note that the FreeStyle Libre reader also doubles as a glucose and ketone meter.)

So, if you’re not monitoring blood glucose, the absolute minimum you should be doing is monitoring glucose and ketones in urine, if not daily, at least a few times a week.

If for some reason you cannot monitor blood glucose or install a FreeStyle Libre, you can monitor water intake, weight (weekly), amount of food eaten (if free-feeding), and general clinical signs like play, purring, grooming, habits, etc.

You will want some kind of notebook or spreadsheet to track your monitoring, whatever form it takes. A shared online spreadsheet using Google Sheets is a great solution (see below).


Don’t do this alone. Managing feline diabetes is a marathon, and can feel overwhelming at first. Your vet cannot give you the day-to-day support you will get from an online support group, where you will benefit from the experience of those who have gone through what you are going through now, and (often) 24/7 support, either for technical questions or simply to cheer you up or hold your hand.

If you speak French, join the group I manage on Facebook, Diabète félin: apprendre à gérer son chat diabétique (groupe de soutien). If you speak German, join the Diabetes-Katzen Forum (where the tight regulation protocol published by Roomp and Rand in 2009 was developed). If you are an English-speaker, join the FDMB (Feline Diabetes Message Board).

Of course there are both cultural and “technical” differences between these support communities, in addition to language. So the advice you will get will not be exactly the same. Here are a few key points on where the views you will find in the French community (therefore mine) differ from those you will find on the FDMB (as this is an English article):

  • In the French group we do not insist on feeding a wet food diet even if tight glycemic control is desired, our experience being that it is perfectly possible on dry food, and we have a good opinion of therapeutic (ie, “diabetic/veterinary”) diets over commercial ones.
  • We recommend starting insulin first, and worrying about diet later, rather than postponing the start of insulin therapy to put in place a diet change.
  • When glucose values are high we increase insulin at an accelerated rate, depending on how much monitoring the caregiver can provide (in line with discussions I have had on the German forum).
  • We encourage the use of FreeStyle Libre continuous glucose monitors whenever possible, as they offer less stressful monitoring for owners. The continuous monitoring allows for more assertive dosing decisions as there is no uncertainty regarding past glucose values.
  • Our management of low glycemic values (50 mg/dl and below on a human meter) is slightly more relaxed than on the FDMB, more in line with the German site. Same for dose reductions, as long as there is sufficient monitoring and owner experience.
  • We don’t give a lot of importance to removing food 2 hours prior to pre-shot glucose tests, and are OK with free feeding.


Food is one arm of diabetes treatment. Feeding a cat a diet with less carbs is going to help bring blood glucose numbers down. But beware: less carbs is not the only thing that counts. The overall quality of protein in the food is important, and some therapeutic diets are formulated to help keep the blood glucose stable (the whole question of which carbs).

This is where my advice strays from the lot of what you will find online. On the French group we have very good experiences with dry diabetes-formulated therapeutic food, in particular Hill’s m/d. The huge advantage of dry food is that you can free-feed the cat (use a food silo – the cat should never see the bottom of the bowl, and shouldn’t know the human is the food distributor). Of course, if you have a cat who likes wet food, that is fine too. Do what works best for your cat and you.

If for some reason or another you need to give your cat another diet (food intolerances or other illness that requires a special diet), it is still possible to get its diabetes regulated. It will just probably require more insulin. Remember that the goal is not to give as little insulin as possible: it is to keep the blood glucose low and stable.

If you are giving Caninsulin or Prozinc, you’ll want to make sure your cat eats a reasonably good meal just before or around injection time, and has the same amount and kind of food over each 12-hour period following an insulin injection.

If on Levemir or Lantus, nibbling throughout the day works fine (total free-feeding). We have seen cats that were very bouncy and hard to regulate on very low-carb wet food become much easier to regulate (with more insulin, but who cares?) and less bouncy on a free-fed dry therapeutic diet.

For some cats, of course, reducing carbs to the max will allow them to be diet-regulated and go off insulin. But pay very close attention to the quality of the food in question – quality is not just about carbs, ingredients (or lack of certain ingredients), or form (wet/dry/raw). It is about nutriments.

I don’t recommend changing the diet before starting insulin. A diet change can bring along a host of problems and with a diabetic cat, you want to start insulin as soon as possible and get clinical improvement quickly. If and when you change food:

  1. do it progressively, over a week
  2. monitor blood glucose levels closely, as they might drop and you might have to reduce the insulin dose

Never change the diet of a cat that is on insulin without close monitoring. It can go into hypoglycemia and die.


Having a diabetic cat comes with a certain number of constraints, the most obvious of which is being there twice a day 12 hours apart for insulin injections, every day.


  • Prozinc and Caninsulin allow flexibility in injection times, up to a few hours, as long as blood glucose is high enough at injection time
  • A well-regulated cat can skip and injection now and then
  • With Lantus or Levemir, if you can’t inject at the normal time, injecting approximately 6 hours after what would have been injection time (give or take a few hours) and skipping the next injection mitigates the “damage” due to the skipped injection
  • It is possible to find (or train) pet-sitters to give injections
  • Some diabetic cat owners take their cat with them on holiday
  • Some places will board diabetic cats
  • If you are not there to monitor blood glucose (the person replacing you will do injections but not monitor glucose) consider putting a FreeStyle Libre continuous blood glucose monitor on your cat.

Many cats reach remission, which means an end to injections. Some cats are so well-regulated that although they don’t reach remission, they can move down to one injection a day (Lantus/Levemir) and skip injections regularly.

Financially: to make a budget, do not look at sticker prices, but calculate how much insulin, food, strips etc. will cost for a month. Dry food is cheaper than wet food, for equal quality. Not all insulin is the same price. Regarding test strips, in Canada the One Drop unlimited subscription is really the cheapest option. In France, we calculated that the One Drop is cheaper if you’re using 5 strips a day or more on average. Do the math for your country! In France, it costs less than 100€/month to give your diabetic cat 5-star treatment. Generally, home monitoring costs less than doing curves at the vet, and decreases the chances you will need to spend a lot of money on an emergency.

Risks and caution

Most people are afraid of hypoglycemia. It is indeed a risk that comes with insulin therapy, but if you are home monitoring, increasing the insulin dose gradually, following safety guidelines and avoiding brutal diet changes, the risk is very small. Having access to food further decreases this risk.

Most serious hypoglycemic episodes I have witnessed or heard of occur after a diet change with no monitoring, large dose increases with insufficient data to justify them, or long periods of injecting the same dose with no monitoring.

What people are unfortunately not afraid of enough is diabetic ketoacidosis, probably because it is a complicated word and “ketones” (despite the popularity of “keto” diets) are not part of our everyday vocabulary or life experience.

I have seen more cats than I can remember die from diabetic ketoacidosis. This is in particular a danger for newly diagnosed cats or badly regulated cats. The absolute first thing one needs to be doing with a diabetic cat is checking urine for traces of ketones.

It is often recommended to skip the insulin dose if the cat is not eating. This advice can be dangerous, as one of the first visible symptoms of ketones will be loss of appetite. Skipping insulin for a cat with ketones will make the situation worse and things have a high chance of spiralling out of control. This is why at the bare minimum glucose and ketone urine checks should be made. On the other hand, injecting a full dose of insulin on a fasting cat who is normally well-regulated can be disastrous too (hypoglycemia).

High doses of insulin are not dangerous as of themselves, and some cats need them. The only risk of “too much insulin” is hypoglycemia, so if you are monitoring to stay safe on that side, there is no reason to be worried about the number of units you are injecting – considered you reached that number progressively and with adequate monitoring.

If you are injecting Lantus or Levemir, injection time is very important (give or take 15 minutes). Injecting less than 12h after the previous injection can lead to hypoglycemia.

What if I don’t treat my cat’s diabetes ?

Not treating a diabetic cat shouldn’t be an option. If it is lucky, the cat will waste away to be just skin and bones, starving and drinking like a fish the whole time. It is not comfortable. If it is not lucky it will start producing ketones and die of diabetic ketoacidosis.

If your cat is diabetic, it needs insulin. What I describe in this article is my “best advice”, but if the alternative is no treatment, then anything is better than nothing – even one injection a day with scarce monitoring.

Many people don’t believe they will be capable of caring for a diabetic cat, be it for needles, constraints, or finances. But trust me, solutions are found, and many people caring very well for their diabetic cat today didn’t think they would be capable of doing it when they got the diagnosis.

Diabetes can really be very well managed, so it’s absolutely worth giving your diabetic cat a chance at life.

My vet doesn’t agree

The advantage of online support groups is that we have the luxury of paying attention to just one illness, whereas a vet has to know everything on everything – and for more than one species. Feline diabetes is a very niche condition, and vets are generally not very familiar with it, and dread it – cat owner reactions tend to range from panic, despair, to asking for euthanasia.

So, vets are generalists, but people in feline diabetes support groups have probably read more on feline diabetes and followed more diabetic cats than most vets, though of course their knowledge on anything outside that field is certainly going to be lacking.

Vets tend to have an approach to treating feline diabetes that makes it as easy as possible on the owner: no home monitoring, just injections, drop the cat off every now and again to check blood glucose (a curve, or in some cases, a single spot test). The consequence is that they aim for an improvement of clinical signs: the cat stops losing weight, stops eating as if it were starving and drinking like a fish, doesn’t go into DKA or hypoglycemia. With home monitoring, however, we can do much better, and aim for remission or great blood glucose regulation, rather than just a stabilisation of clinical signs.

Also, vets, like other medical professionals, are often faced with people who have “found information online”. 99% of the time, the information in question is crap. So, don’t assume your vet is going to take seriously your “online research” on feline diabetes, even if you can see that it is solid.

Links and conclusion

I’ll probably add to this article as I remember things I have forgotten to include. I hope you found some useful information here! To finish, here are links to some recent publications on feline diabetes if you want to read more.

Photo: Quintus and Oscar, my two diabetic boys (one in remission, the other with a FreeStyle Libre)