What To Do With Insulin When Your Diabetic Pet Is Vomiting Or Not Eating

By Dr . Joi Sutton|2023-09-25T13:24:23-04:00Updated: June 25th, 2015|Pet Care, Pet Diabetes, Pet Diet & Nutrition, Pet Newsletter|33 Comments
  • Dog sitting next to owner being comforted

Once you have your diabetic pet regulated on insulin it’s smooth sailing, right? Well, not necessarily. Even a well-regulated diabetic doggie may mischievously get into the trash and subsequently vomit. Or Fluffy might toss up a random hair ball. Just because your pet is diabetic doesn’t mean it can’t have a dietary indiscretion or gastroenteritis the same as non-diabetic pets!

Even if you are new to having a diabetic pet, if you understand the basics of diabetes (most importantly that insulin drops the blood sugar levels) you can work your way through a short-term treatment plan. You know that insulin allows sugar (from the food we eat) to enter our cells. Without food, giving the usual dose of insulin could drop the blood glucose to dangerously low levels. However, if the blood glucose is still quite elevated, you might consider giving a lesser dose of insulin even if a diabetic won’t eat. You know your pet… Some have a sensitive stomach whereas others might have the constitution as sturdy as a goat. Some have ravenous appetites whereas other pets may be finicky. None of us have a crystal ball when it comes to predicting if a pet will vomit more.

Not eating and vomiting are both situations that put us in the same boat in regards to insulin dosing. No food in the tummy means there is nothing for the insulin to utilize. Of course, vomiting is worse than simply not eating because we don’t know why the pet is nauseous nor if there will be more vomiting to follow. Not eating may simply be that a pet isn’t hungry.

Obviously you need a good relationship with your veterinarian to help you work through contingency plans for these situations, but I want you to understand in general what we might do. Of course making choices to alter the insulin dose mandates that you have a blood glucose meter at home. I think the vast majority of our readers do have a blood glucose meter for their pets. You likely use it to run periodic blood glucose curves so that you and your vet can evaluate your pet’s insulin dose and recommend the usual insulin dose for your pet. However, if your pet doesn’t eat or if your pet eats and then vomits, you can use the meter to run a spot check of the blood glucose.

Here’s where the tricky part comes in: Just how much less insulin shall we give if a pet doesn’t eat or if a pet vomits? This depends on the pet’s blood glucose. If the blood glucose is sky high in the 400s or more, you might give half the regular dose even if the pet is vomiting or not eating. If the blood glucose is normal or only mildly elevated you would clearly skip the insulin dose. In between I’d advise you to be very cautious with insulin doses. As a short period of a high blood glucose level is much safer than a short period of a low blood glucose level! Contact your veterinarian. And if the anorexia or vomiting persist until the next dose, you better get your pet into the vet office pronto.

Years ago when I was an ER vet, I recall numerous times when clients got confused as to course of action for a diabetic pet who was vomiting or not eating. I recall several times when clients gave their diabetic pets extra insulin in these situations instead of backing off on the dosage. Don’t be that pet owner. If you have any doubt, contact your veterinarian. Otherwise you may just end up with a pet in a hypoglycemic crisis, hospitalized on IV fluids spiked with dextrose.

You know I like hearing from our readers. Don’t hesitate to email me at [email protected].

NOTE: Consult your veterinarian to confirm that my recommendations are applicable for the health needs of your pet.

About the Author: Dr . Joi Sutton

Dr. Joi Sutton is a 1993 graduate from Oregon State University. She has practiced both in emergency medicine and general practice. Dr. Sutton has done extensive international volunteer work though Veterinary Ventures, a nonprofit organization that takes teams of veterinarians to undeveloped countries for humane medical care. She also runs a small animal practice in South Florida. Connect with Dr. Joi on LinkedIn


  1. Patricia November 7, 2023 at 3:42 am - Reply

    My 10-year-old Westie has pancreatitis and diabetes. Her pancreatitis manifested suddenly around a month ago, and she sought treatment and a diagnosis from the veterinarian. Even though I’ve been able to control her condition thus far by giving her small meals throughout the day to prevent attacks, as soon as it appears that she is improving, she has an attack and throws up. As you can imagine, her readings spike when she’s like this. She is losing weight, which worries me, and she is often thirsty and hungry, searching for food. She mopes about if she isn’t doing that – not her usual playful self. She’s on a special low-fat dog food to try to make her feel fuller, but it’s not working. Any advice please would be gratefully welcomed.

  2. Ann Marie February 12, 2023 at 3:58 pm - Reply

    How long can I go without giving my diabetic dog insulin if he won’t eat & has thrown up?

    • Dr . Joi Sutton February 19, 2023 at 3:57 pm - Reply

      You’ll want to take him to the vet if he isn’t eating and is vomiting. If it is a few hours you are likely fine to wait til the next insulin injection, but if your diabetic pet is ill and vomiting you clearly need to take him to your veterinarian.

  3. Anonymous February 12, 2023 at 8:27 am - Reply

    My diabetic 13 year old dog would not eat all day. I did not give any insulin all day. Two days prior had him to the vet because he would not eat & throwing up phlegm. She did blood work blood sugar was 435 she said since was sick expected to be high. She gave him shot for infection & shot for nausea. Then gave insulin when we got home. Next day he ate scrambled egg so gave insulin. Evening he ate chicken gave him insulin. Next day throw up & would not eat. Don’t have meter to check. He is drinking & did spit up some water. Will not eat. Please help

    • Dr . Joi Sutton February 19, 2023 at 3:55 pm - Reply

      First of all, I do hope you get a blood glucose meter for your pet to help guide you through future situations. For now, you need to take him back to the clinic for ongoing care–perhaps other diagnostics and anti-nausea meds and such to get to the bottom of his issue.
      Good luck,

  4. Jessica August 14, 2021 at 7:16 pm - Reply

    My diabetic dog vomited this am after his morning glycobalance meal and 3 units of insulin. I checked and his blood sugar was 70. I fed him a little bit of food and then took him to my vet. She said he seemed fine and his blood sugar was 204. Later this evening he started to act lethargic, panting and did not want his dinner. I checked his blood sugar again and it was 284. My vet has closed, so I gave him a quarter dose of his insulin and will be monitoring throughout the evening. I would absolutely take him to the ER vet, but unfortunately I am still paying off the 4k in vet bills from when we discovered he was diabetic. I applied for care credit, but it has all gone towards his care. Not sure why these things always happen on a Saturday evening. Please give advice if able.

    • Dr . Joi Sutton August 15, 2021 at 1:41 pm - Reply

      Jessica, what you did makes perfect sense. Good job checking the blood glucose and decreasing the insulin dose to a fraction of the normal dose based on home glucose monitoring. This is exactly why owners of diabetic pets should have a blood glucose meter at home.

  5. Judy Applebey June 14, 2021 at 4:31 am - Reply

    I don’t have a glucose meter in my cat is 15 years old has been on diabetic medicine for 4 months and he’s now throwing up three times one day.

    • Dr . Joi Sutton June 16, 2021 at 10:19 am - Reply

      You need to take your sweetie to the vet now. She needs anti-nausea medications and some diagnostics. I strongly advice home glucose monitoring. On this website I wrote an article years ago about “tips and tricks” of getting a blood glucose sample from your pet. In this day and age, with such great pet glucose monitors on the market that require minuscule amounts of blood to measure a blood glucose in a dog or cat—species specific monitors no less, it is the standard of care to check blood glucose at home. It’s not only more accurate (by removing stress hyperglycemia that can happen in a vet clinic), it’s also way more affordable for pet parents to manage a diabetic pet. There are some great free online resources for diabetic pets. My favorite is the 2018 AAHA Diabetes Guidelines. I think all pet owners with diabetic pets should strive to read up on pet diabetes. Do please take your pet to the veterinarian today. 🙂

  6. Malia Veltrie March 26, 2021 at 8:36 pm - Reply

    If you see this help…my vet is in surgery so they told me to try to go somewhere new… newly diagnosed 13 ye old diabetic dog. Been giving 3ml(ml?) 2 times a day after food. Last week he has had a great appetite and today he ate breakfast but threw it up 4 hours later. Shortly after I felt like he was empty so I tried to see if he would ear a bit of plan white chicken. He did. He then had diareah and threw up again. I checked his glucose and it was a 305. 5 hours later he has thrown up again and his glucose reads 139. Should I try to feed him and give him his insulin tonight or is it OK to not give him anything (food or insulin) and just take him to the vet first thing in the morning?

  7. Cali January 14, 2021 at 3:49 am - Reply

    Hello, I’m writing this as the incident has just occurred even though It’s 3am and know nobody will see it right away. However, in case this happens again I’d like to ask:
    My cat ate at 10pm, got his insulin shot and then snuck up and found some other cats food around 11pm and ate some.
    At 3:20am I woke up to him throwing all of his food up. I measured his blood sugar level to be 115 so I’m thinking that’s okay since it was about 5 hours after he’s eaten anyway and should be low, but not too low.
    My question is, if a cat throws up in the middle of the night like that, how quickly would you see the change in blood sugar? Should I measure it every hour after that? It’s hard because I don’t want to fall asleep and then he gets low blood sugar.

    Maybe I’m worrying too much…
    Thank you for any insight!

    • Dr . Joi Sutton January 17, 2021 at 8:42 pm - Reply

      If only we had a crystal ball to predict what will happen to an individual’s glucose after vomiting. You did just right to check your pet’s blood glucose. If it had continued to go down you could have tried offering a bit of food (knowing he might just vomit it up again) or go to an ER hospital where if he became hypoglycemic they could set an IV catheter and put him on a dextrose drip. I’m so glad you have a glucose meter. Good job.

  8. Connie November 19, 2020 at 11:10 pm - Reply

    Hi Sutton,
    I found out 3 weeks ago that my 15 year old cat is a diabetic. His glucose levels were 556. I believe his 3 units of insulin every 24 hours may be too much because he has started back vomiting and drinking alot of water. I also changed his dry food to purina md…it seems to not agree with him so I will be stopping it. Please help me because I’m concerned and want to make sure I’m doing everything I need to help him.

    • Dr . Joi Sutton November 22, 2020 at 6:25 pm - Reply

      MD diet is one of the few diets specifically formulated for diabetics. Good job on choosing it. However, diabetic cats do better on canned diets. Canned foods are lower in carbs than dry foods. There is canned MD. There is also a Purina diabetic diet called DM that I like very well. Your kitty stands a much greater chance of going into remission if you feed a canned diet and no dry food.

      Next, I have never known a cat nor dog who was regulated on once a day insulin. Although Vetsulin is labeled for once a day injections, I’ve yet to meet a pet who was reg7lated on that. Please chat with your vet about splitting the injections into every 12 hours. My favorite insulin for cats is glargine. You can save money by purchasing a 3 cc pen over the 10 ml vial as cats use so little insulin.

      Next, I hope you get a blood glucose monitor to test your kitty’s glucose levels at home. You need to be able to react if your pet vomits as to insulin injections. You should take your kitty back to your vet for re-evaluation since there is vomiting. Your vet may need to do diagnostics. You might also,eep some anti-nausea mess at home.

      Consider reading the 2018 AAHA Diabetes Guidelines which are available online for let diabetes.


  9. Jan November 13, 2020 at 8:22 pm - Reply

    My diabetic dog is on meds for bronchitis. One med made him vomit. I called the vet and they are putting him on a new med tomorrow . He has not eaten and I gave no more insulin or meds.
    He has not eaten but went for a wsalk. Tonight he is resting but his legs are shivering. It’s not cold in the house. Is he OK?

    • Dr . Joi Sutton November 15, 2020 at 3:56 pm - Reply

      You should check his glucose. A low glucose could cause shivering.
      The shivering could also be from fever or cold or weakness. If you feel your pet is doing poorly and cannot wait til tomorrow there are ER vet’s in most large cities, and you should consider taking him there today. Best, Joi

      • Lorie May 11, 2023 at 10:51 pm - Reply

        My 12 year old diabetic dog was acting different not excited at all about her insulin. Are very little n aster that threw up . I gas already at that time given her insulin with the little food she ate . She’s drinking water but seems off . I will wait till tomorrow morning n see if she wakes up better

        • Dr . Joi Sutton June 3, 2023 at 7:43 am - Reply

          If a pet is nauseous, inappetant, or vomits and you give her regular dose of insulin, her blood glucose could go low. The most common sign of hypoglycemia in pets is nothing at all, but if she seems sleepy or “off” there is a good chance that her blood glucose is too low. Hopefully you have a home blood glucose meter. My favorite of the home meters is the Alphatrak because it requires such a tiny droplet of blood and is calibrated for dogs and cats. Human blood glucose meters often underestimate the blood glucose of pets. Having a meter at home means you can run the blood glucose curves at home rather than pay your veterinarian to do so. Besides, blood glucose curve are more accurate when the pet is in it’s home environment rather than in a vet clinic which is often scary for a pet which can artificially elevate the blood glucose from stress hyperglycemia. I have an article (written years ago) on this website called “tips and tricks” for getting blood glucose from your pet. It’s not difficult for most pet owners and I urge you to do home testing, particularly if your pet has tummy upset. Knowing the blood glucose guides you for situations like this as to if you should give a lesser insulin amount or should skip a dose altogether. Have a chat with your vet! 🙂

  10. Anonymous November 9, 2020 at 6:17 am - Reply

    This has been very helpful for me, my diabetic girl was vomiting and diarreah all day yesturday so I skipped her insulin last night she seemed a little better this morning and ate a very small amount for her breakfast and kept it down most of the day without vomiting but just before dinner time it all started again both diareah and vomiting, I never gave insulin all day today but am going to the vet tomorrow..I just wanted to know about the insulin in this instance as she is on 9 units twice a day normaly

  11. Barbara Pound October 24, 2020 at 7:39 pm - Reply

    I have not been able to check Toby’s blood sugar with my monitor. He is a silky terrier about 12 years old. Has had diabetes a little over a year and has done ok except he developed cataracts and is blind. Yesterday he wouldn’t eat. Drank a lot of water and wet all in my kitchen. Then started vomiting a lot. Very sluggish and not eating.

    • Dr . Joi Sutton October 26, 2020 at 7:21 am - Reply

      Barbara, learning how to check your diabetic pet’s blood sugar is important for times like this to guide you in regards to blood glucose and feeding. Have you been able to check his glucose in the past or do you need help learning how? In the articles I wrote a few years ago there is one called “tips and tricks” for getting a blood sample that you can search in the articles. The blood glucose meter I prefer is the Alphatrak because it requires such a tiny droplet of blood. Having the ability to check a glucose with a meter matters. Plus, it will save you money when it comes time for blood glucose curves! Do take your sweetie to your vet promptly for evaluation. Best, Joi

  12. Carol Wakefield October 10, 2020 at 3:33 pm - Reply

    My diabetic kitty has thrown up twice in 5 hours. She first ate at 7 a.m. and at 7:30 vomited it all up. About 4 hours after she first ate and had her injection, I gave her 3 small pieces of dried chicken breast. About a half hour later she threw that up also. She isn’t lethargic and is still hungry and acting normally. Should I be concerned?

    • Dr . Joi Sutton October 12, 2020 at 9:47 pm - Reply

      If the typical cat vomits once or twice it’s not earth shattering. However, your kitty is diabetic. It could lead to trouble as without knowing her blood glucose level you won’t know what to do with her insulin in such circumstances. I hope you have a blood glucose meter to help you determine if you should skip the insulin for a dose or lower the insulin. Your veterinarian who has examined your sweetie can help you sort this. If there is any more vomiting she should be seen promptly by your vet. If there is any lethargy or inappetence you should also see your vet. 🙂

  13. Joanne June 15, 2019 at 10:10 am - Reply

    Dear Dr Joi Sutton,

    My diabetic dog vomited out the food after injecting insulin , what should I do now ?
    Unable to contact my vet , can you please help , thanks

    • Dr . Joi Sutton June 16, 2019 at 4:27 pm - Reply

      First of all, this is an excellent reason to have a blood glucose meter at home. It helps you make wise choices. Without knowing the blood glucose you don’t know if there is hypoglycemia. You may need to go to the ER if your pet shows signs of hypoglycemia for IV dextrose. Or, if your pet only vomited once, you might try feeling a small snack of some bland food say an hour or 2 later.
      It’s a good idea to discuss this scenario with your vet. Perhaps they have an after hours service for your clinic or someone on call. If your pet is prone to stomach upset you might have a prescription of an anti nausea medication at home as it is a weekend. If there is further vomiting, do please head to the ER. Or if your pet shows any signs of a low blood glucose also you must go to the ER until you can contact your vet. Best, Joi

  14. Darren g Briscoe November 19, 2018 at 11:27 pm - Reply

    My comfort companion aka my cat first started to clean himself perfusely after using the litter box which is usual a sign of the runs, Then he throw up a regular size hairball. The he proceeded to vomit all over the flooring and poop in sequence between all 3 of my litter boxes . So it was puke, poop, puke, poop in sequence ( I have 2 cats and my Parents have 2 cats, Mine are Indoor only and theirs are Indoor/outdoor so I check for outside influence on my felines constantly) My cat has both UTD and Diabetes so I vigilantly keep an eye on his urination and bowel movements so I am rarely surprised.This incident was very surprising, I am now going to have to invest in a meter so I can make sure its a blood sugar issue when he gets sick like this, He lacked an additional symptoms for Hypoglycemia and last dose of 2 units of Insulin was 11 hours ago. I was able to access this site and got enough cursary information to be able to accertain that he probally a more mundane reason for his illness. That being the wet food he keeps getting from my father who overfeeds most cats too much wetfood. I decided to refrain from giving the insulin shot until later when he eats and drinks because his stomach is upset enough he refuses to eat or drink which in itself is very unusual. Thank you again for the information it did come in handy.

    • Dr . Joi Sutton November 23, 2018 at 11:36 pm - Reply

      Yes, please do get a pet glucose meter! I can’t fathom having a diabetic pet without the ability to measure the blood glucose. Without a meter it is all guessing. My favorite meter is 5e Alphatrak 2 meter. It is very user friendly.
      Feeding too much is bad, but feeding a diabetic cat canned food is a good thing. Canned food is much lower in carbohydrates than kibble. I advise against dry food for diabetic cats.
      Best to you! Joi

  15. John W Craft October 1, 2018 at 5:21 am - Reply

    Great information and advise. This morning Jordan threw up. Prior to that she ate grass. After throwing she was very weak and did not want to eat, very abnormal for her. We finally got her to eat. I’m going to reduce her shot this
    AM and watch her. Thank You

    • Dr . Joi Sutton October 17, 2018 at 8:52 pm - Reply

      Thank you! Be sure to chat with your vet about a plan in case this happens again. And having a blood glucose meter will help you make choices about her insulin. 🙂

  16. Linda Rodriguez June 5, 2018 at 12:36 am - Reply

    Thank you so much! My cat had to go without her insulin for 16 hours. I worked that long yesterday. She was so Hungry when I got home she ate way too fast and ended up vomiting everything up. I held off on the insulin until I thought she could keep some food down. Since she is only on 1 unit I did not decrease it. She did eat a small amount of the Hill’s dry food. By morning she was back to normal. Unfortunately my carpet is not. 🙂

    • Dr . Joi Sutton June 10, 2018 at 8:40 pm - Reply

      Good job. That’s a pity about the carpet. :/

  17. Anonymous April 3, 2018 at 11:05 pm - Reply

    Thank you so much for your advice. I feel so much better now. I am glad that this has happened to other cats, too. Thanks again !!!

  18. Liza January 8, 2018 at 3:19 am - Reply

    Thank you so much for sharing this. It has been very helpful.

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