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The Daily Vet by petMD

The Daily Vet is a blog featuring veterinarians from all walks of life. Every week they will tackle entertaining, interesting, and sometimes difficult topics in the world of animal medicine – all in the hopes that their unique insights and personal experiences will help you to understand your pets.


Diabetes is a life altering disease for cats, dogs, and the people who take on the daily insulin administering and financial backing roles.


There are two types of diabetes affecting our companion animals: mellitus and insipidus. Mellitus is the more common form and includes type I and II.


Diabetes insipidus (DI) is uncommon; it results from a deficiency in or lack of kidney sensitivity to arganine vasopressin (Antidiuretic Hormone, or ADH), a hormone produced by the pituitary gland which promotes the kidneys’ retention of water. My focus is on mellitus types I and II, but read more about DI in Water Diabetes in Dogs.


Types I and II mellitus arise for differing reasons in dogs and cats, but both involve an overall deficiency in insulin production. Insulin is a hormone that moves glucose from blood into tissue and is secreted by pancreatic islet cells.


Insufficient insulin levels cause hyperglycemia (elevated blood sugar) and glucosuria (presence of glucose in the urine), both of which are detectable via diagnostic testing and cause notable clinical signs, including:

  • Excessive water consumption (toilets, buckets, and stray puddles of water become enticing)
  • Increased urination (volume and frequency, so reconsider your plan for new rugs)
  • Ravenous appetite (which can lead to consumption of inappropriate objects and substances...yuck)
  • Weight loss (despite increased appetite, which sounds like a Beverly Hills housewife’s dream)


Glucose deprived tissues prompt the body to inefficiently metabolize protein, stored carbohydrates, and fat. Protein and carbohydrate breakdown produces glucose, while fat metabolism releases toxic ketones. This process, akin to starvation (or the once commercially touted Atkins diet), causes metabolic chaos. Dr. Siobhan O’Neill, an internal medicine specialist from Advanced Critical Care (ACC), states that "poor glycemic control can result in weight loss and the development of diabetic ketoacidosis, a condition requiring hospitalization for the management of life-threatening electrolyte alterations and dehydration."


Type I mellitus is the typical canine variety resulting from pancreatic damage associated with chronic inflammation of the digestive tract (Inflammatory Bowel Disease, etc) and pancreas (pancreatitis), infection, and toxin ingestion. When enough islet cells are damaged, insulin is insufficiently produced, blood glucose levels rise, and the diabetic process ensues.


Type II diabetes is more commonly seen in cats and results from the pancreas’s inability to make enough insulin to support a body burdened by excess weight. At fault are cat owners who permit overfeeding, which leads to our feline friends suffering the ill effects of obesity, including diabetes (see Pet Obesity: Health Implications, Recognition, and Weight Management).


Before you decide to "top off" your pet’s scoop of food or skip a much needed hike, consider the economic implications associated with diabetic pet health care. Can you afford the projected ongoing medical expensed incurred by a diabetic pet? According to VPI Pet Insurance claims data, diabetes related veterinary expenses totaled more than $1.5 million in 2007, with an average invoice of $200 per visit.


What are my top holistic tips to prevent our dogs from developing a type I diabetes? Focus on maintaining an optimally functioning digestive tract, which helps keep the endocrine (pancreas, kidneys, liver, etc), immune, and other body systems healthy.


Dr. Amanda Blackburn (another ACC internist) notes that "remission of insulin dependence in dogs after an appropriate diagnosis of diabetes is extremely rare." Avoiding processed foods and treats containing byproducts, protein and carbohydrate meals, preservatives, and artificial colors and flavors can help to relieve your potential lifelong responsibility to inject your dog with insulin.


Cooked, fiber rich, whole food sources can reduce intestinal and pancreatic inflammation, promote healthy gut bacterial levels, and are less likely to include toxins found in pet grade foods. (SHOCKER: The pet food industry makes allowances for plastic and styrofoam, which can disrupt your pet’s normal glandular function.) Additionally, prevent dietary indiscretion by canine proofing your home environment and keeping your dog on a short leash when setting paw outdoors.


A similar principle of prevention applies to type II diabetes in cats. Emphasis must be placed on calorie restriction, as the feline obesity epidemic continually yields new crops of diabetic cats.


Society has been lulled into believing that cats must eat foods having a format grossly different from nature’s intention. Cats are obligate carnivores and should eat primarily meat protein and minimal grain based carbohydrates. Consuming grain rich, processed options (dry or canned) insufficiently satisfies cats’ biological needs. As portion control is inconvenient for people and organically unfamiliar to cats, excessive food will be consumed unless feline caretakers responsibly promote calorie restriction.


Dr. Blackburn gives hope for feline diabetics when he says that "approximately 50 percent of cats can revert to a non-insulin dependent state with dietary alternations, weight management, and short term insulin therapy. Therefore, owners of cats with early signs of glucose intolerance or newly diagnosed diabetes can positively impact their cats’ health with weight loss and dietary alterations, and by avoiding medications such as steroids, which can predispose a cat to diabetes."


Starting today, dog and cat owners should put the utmost effort into preventing their companions from developing diabetes mellitus by feeding appropriate portions, providing pure food sources, averting dietary indiscretion, and engaging in frequent pet-people exercise.


Pictured: A cat that is well on its way to being diabetic.



Dr. Patrick Mahaney



Image: Irina oxilixo Danilova / via Shutterstock

Comments  19

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  • diabetes and diet in cats
    11/15/2011 03:42am

    Thank you so much for posting this. Recently there was a post I replied to either in the daily vet or vet md about vegan diets for cats and dogs. This is one of my pet issues. These animals are carnivores and have evolved to be so. If we wish to have them in our lives, along with the joy they provide, we are obliged to feed them appropriately, and not project ourselves upon them. I even think sometimes about buying an occasional mouse for my cat so he can have this live food experience, but have refrained thus far. He has apparently eliminated all the mice from the immediate environment. What does anybody think about this?

  • 11/16/2011 08:15pm

    Thank you for your ongoing readership and comments!
    As I indicated in my article, I strongly feel that animals should eat and benefit from whole food feeding as compared to man made convenience foods. Modern day pet health is greatly suffering the "Supersize Me" effect as evidenced by canine and feline obesity, especially as pertains to feline diabetes.
    Dr PM

  • 11/17/2011 01:47pm

    @Dr Mahaney, I fully agree that making whole foods is a better option, however some people just don't have the resources and time to put this into practice, which was why I mentioned commercial foods that work in a comment below. This doesn't suggest at all that I don't agree with you. It is too bad there aren't more good resources online to promote whole foods being fed, but as so much is turned into a "raw food" issue, people are turned off and tuned out. Can you expand with some good choices in your blog that can also be cooked for those who wish to feed immune compromised systems more safely? Sometimes there are people who push perfection in feeding to the extreme so the general population doesn't feel that feeding their cat in the same manner as they would feed their children is adequate. With appropriate ingredients it should be just fine, IMHO.

  • 11/20/2011 02:16pm

    Home prepared diets can be tricky and are best done under guidelines of experienced/trained individuals.

    My top recommendations for an owner to use to go the route of home prepared diets for their pets are:

    1. UC Davis Nutritional Support Services (works in conjunction with your vet)

    2. Balance It

    Dr PM

  • Sometimes...
    11/15/2011 07:16am

    And sometimes a kitty becomes diabetic out of the blue.

    My CRF (chronic renal failure) kitty developed diabetes. We had her on Lantus, but were unable to get her BG (blood glucose) under control. We tried low carb diets with no effect.

    After switching her to the new PZI (no longer a beef-pork recombinant which used to work so well), she reverted when she went into the hospital for a fluids drip, trying to bring her kidney number down. Her kidney numbers didn't come down, but she never needed insulin again!

    One never knows if a kitty will revert, so it's important to keep a close eye on kitty's BG. It's not difficult to check it at home with a human glucometer (I won't touch a kitty with insulin without checking the BG first) and it quickly becomes routine.

  • 11/16/2011 08:20pm

    Thank you for your comments and for sharing your personal story with feline diabetes.
    Good suggestion regarding checking glucose levels at home.
    At least getting a frame of reference for BG before giving insulin can help to avoid potentially life threatening hypoglycemic episodes.
    Dr PM

  • 11/16/2011 09:19pm

    My first diabetic kitty was SO unregulated that she really gave me a crash course on being extremely vigilant about checking her BG.

    I hear people say that Fluffy does just great getting X units a day and they don't monitor at home. It always makes me cringe until I realize that most cats don't have a BG of 40 when they eating normally or a BG of 400 when they haven't eaten for awhile. I never had a clue what Emma Jean's BG was going to be.

    I'm such an advocate of doing BG checks at home. Doing curves is no big deal and it saves a great deal of stress on everyone involved - not to mention being a whole lot cheaper than a curve at the clinic. I also feel that it's a lot more accurate because the kitty is eating normally and isn't stressed.

  • 11/20/2011 02:18pm

    Certainly having a reduced stress environment can lead to fewer false readings of hyperglycemia.
    Even collecting a blood sample at home can be stressful for a pet, so we have to consider that in the equation as well.
    There is no "right" answer. We just need to look at all aspects, do our best, and strive for consistent care.
    Dr PM

  • Caloric Intake
    11/15/2011 03:07pm

    Thank you so much Dr Mahaney for being a veterinarian who gets it. There has been a fair amount of research coming out since about 2006 on the subject of gonadectomies, (pet alterations), causing changes in hormones, and thus creating a problem for our pets. My favorite line on this came from Dr Deb Zoran who used the phrase, "plunged into menopause" when discussing the new emerging scientific data: http://www.ncbi.nlm.nih.gov/pubmed/12027507

    Jacquie Rand has a number of papers published on feline diabetes that include fat, (ie calorie), restriction as much as the carbohydrates in pet foods, such as the following one: http://apjcn.nhri.org.tw/server/APJCN/ProcNutSoc/2000+/2003/Rand.pdf You may note that she interprets "low fat" diets to be less than 25% of calories, and as fat contains more than twice the calories per gram as other nutrients, that means 12.5% fat. Carbohydrates increase the whole glucose curve so also need to be under control, but from my perspective there has been little said about the fats, (calories), for all the time I have been watching the liturature.

    Part of the problem is the fact that the FDA and other such agencies refuse to actually set numerical values to the terms "low fat", "low carb", and "high protein".

    How great it is to see online veterinarians picking up on this so that our pets can benefit.

  • 11/21/2011 12:49am

    Thank you for the suggestions. I will check out the NIH article. I have my doubts of the overall health benefits of gonadecomty procedures for our companion animals.
    I have downloaded the PDF of the article and will give it a read very soon.
    I appreciate your readership and hope to see you back again.
    Feel free to communicate with me through my website.
    Twitter @PatrickMahaney

  • Owner are at fault
    11/16/2011 01:24pm

    And we need more messages like this to raise awareness and education. This has been a good kick in the pants to take more time with my pets for playtime and exercise. It all depends on the owners.

    However, if someone could recommend a good brand of canned food and dry food that has good balance of nutrients. I can handle portion control, but I never know which is the better brand for cats. Labels of pet food is not like human food. They only mention MINIMUM quantities of ingredients vs. exact amounts.

    Would appreciate it! Thanks.

  • 11/21/2011 12:53am

    Thank you for your comments.
    So far, when I have talked the discussion of about portion control for pets and weight loss for pets, my readers have raised the caution flag as to not hurt anyone's feelings.
    With that said, people need to stop making excuses for themselves and their poor habits as pertains to their own health and that of their pets.
    Overfeeding a child or pet is neglectful. "Giving" them an obesity related illness borders on criminal. Who is really saving who(m) when it comes to food.
    My preferred brand of canned cat food is FussiCat (see www.fussicat.com), which is whole food based and made in SoCal (I am in LA, so I have promote local economy).
    Dr PM
    Twitter @PatrickMahaney

  • Owners are at fault
    11/16/2011 02:44pm

    @MiamiAngel, owners aren't expected to be aware that when their cats are altered, there is also a major adjustment to hormonal balances in the body -- that part is up to veterinarians, so please don't take on more guilt than that perhaps you should have been asking questions when weight started increasing.

    As for the foods, we lood for high protein first on the labelling, and second we look for the caloric count. What we persoanlly found to work best for our crew is free feeding Royal Canin dry, (Indoor 40), or even better is the RC Diabetic DS 44. I have heard and read the experts recommending the diabetic, and also agree with the second choice that keeps coming up for a canned food, which is the Fancy Feast high protein product. I think that would be "Classics" in the US.

    We took in the cat who had the damaged pancreas after he had been a stray for about three years that we knew of, and because he had been foraging for food and was very skinny, (previous injury prevented hunting), he had learned to wolf down any food in view. Luckily he couldn't jump onto furniture and we chose to use timed feeders for him, putting food for the other cats up high. We fed him 18 crunchies every two hours using two of the Cat Mate 20's so he wouldn't nag us, and eventually found his habits and his stomach had changed so much that timed feeders were no longer necessary. I am not sure how others in multi-cat households would handle this.

  • 11/30/2011 09:12am

    Good article, it may also be interesting to know that approximately 35 million dogs are overweight and all predisposed to getting type II diabetes. Vets are seeing a big uptick in diabetes because of this. The best way to screen for diabetes is to use the human gold standard test A1c. The is one company focused on bringing this test the vet market, Baycom Diagnostics.

  • 12/01/2011 02:22am

    Thank you for your comment and bringing up an interesting topic.
    So, the thought is to use the human test on dogs to determine if they having consistent elevations in blood sugar due to the corresponding elevation in Glycosylated Hemoglobin?
    Are any veterinary internists currently using the Baycom Diagnostic test?
    Dr PM

  • 12/01/2011 12:53pm

    I wouldn't think that the A1c would be a better choice than the fructosamine, at least for cats, (haven't experienced canine diabetes), as the fructosamine can be done every ten days if needed to check whether a dose of insulin needs to be raised or lowered. The A1c covers a 30 day period and would be far less accurate, IMHO.

  • 12/05/2011 11:20am

    Sorry for the delay in getting back to you. I got a sinus infection last
    week that zapped me. You are correct, the product will be to test for
    glycohemoglobin in cats and dogs. 5 years ago, I thought this would be a
    pretty easy thing to do and be a great product to help vets diagnose and
    manage diabetes. A1c is the gold standard in humans as you probably know.
    It turned out to be much harder than I anticipated. Cats were the really
    hard one. Their hemoglobin structures is just different enough from humans
    that most if not all of the commercially available A1c test for humans do
    not work for cats. I have recently solved this and will be starting
    another small scale testing product trial with vets. Gus

  • A1c vs Fructosamine
    12/05/2011 01:32pm

    @Gray, while it is admirable that you have found a way for the A1c to work for cats, I still don't understand why this would be a more viable form of testing as the results of a fructosamine determine a shorter period of time and usually quicker results are what is needed to determine whether an insulin dosage is accurate. Perhaps you mean it to be used to decide whether the cat actually has diabetes or not? Would a longer period of measurement work better for this?

  • 12/05/2011 03:01pm

    Fructosamine is also a good test. The scientific journal articles show that it can be difficult to get consistent results but it is still a good test. The big issue with cats is they can go in and out of the diabetic type II condition. If the vet were to use glucose or fructosamine alone it could result in a miss diagnosis. A1c gives you the average glucose level for the last ~90 days and thus should have a better chance of diagnosing a cat that goes in and out of the diabetic state. I am also working on a glycated albumnin (30 day average) test which would give the vet a choice of glucose, fructosamin, glycated ablumin (30days) and/or A1c (90 days).

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