# ProZinc Insulin for Cats: Dose, Syringes, and Monitoring ProZinc insulin for cats is a protamine zinc insulin (PZI) product that your veterinarian doses for your individual cat, usually starting around 0.25 U/kg (often 1 unit per cat) every 12 hours under the skin [1]. It is one of the most common insulins used for newly diagnosed feline diabetes, and it must be drawn up in U-40 syringes because of its concentration [2][1]. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - ProZinc is a protamine zinc insulin (PZI) given by subcutaneous injection, most often twice daily, about every 12 hours [1]. - The typical starting dose in cats is 0.25 U/kg, which often works out to about 1 unit per cat, but your veterinarian sets the actual dose [1]. - ProZinc is a U-40 insulin, so you must use U-40 syringes. Using U-100 syringes will give the wrong dose [2]. - Most cats need two meals of equal calories per day, each given right before the insulin injection [1]. - Home monitoring with glucose curves or a continuous glucose monitor helps your veterinarian adjust the dose safely. ## What Is ProZinc Insulin and What Is It Used For? ProZinc is a form of protamine zinc insulin, often shortened to PZI. It is an injectable insulin used to treat diabetes mellitus in cats. Injectable insulin is a mainstay of feline diabetes treatment and has generally been considered the standard of care for cats with this disease [2]. Diabetes in cats means the body cannot move sugar from the bloodstream into the cells that need it. In Type I diabetes, this happens because insulin production drops. In Type II diabetes, it happens because the body's cells do not respond properly to insulin. Either way, blood glucose climbs while the cells starve for energy [2]. Veterinarians choose among several insulin types for cats, including lente insulin (Vetsulin), ProZinc, and glargine insulin. These differ in cost, how long they act, and their concentration, so the choice is a conversation between you and your veterinarian [2]. For cats with newly diagnosed diabetes, protamine zinc insulin and insulin glargine are the most common choices, and they produce comparable glycemic control and remission rates [1]. ProZinc is not the only reasonable option. No single insulin formulation should be considered best by default for feline diabetes. The right choice depends on your cat's specific clinical situation [3]. If you want to compare options, our guide to [insulin glargine for cats](/knowledge/veterinary-medicine/calculators-clinical-tools/insulin-glargine-for-cats-feline-diabetes-dose-and-glucose-curve) walks through a different long-acting insulin. ## How ProZinc Works in Cats Insulin is a hormone that acts like a key. It unlocks cells so glucose can move out of the blood and inside where it is used for energy. When insulin is missing or ineffective, glucose builds up in the blood even though the cells are hungry [2]. ProZinc pairs insulin with protamine and zinc. That combination slows how quickly the insulin is absorbed after injection, which stretches its effect over a longer window than plain insulin. This is why PZI products are given on a twice-daily schedule in most cats [1]. The goal of treatment is not to make blood glucose perfectly normal every hour. The goal is to control clinical signs (excessive drinking, urination, and appetite), avoid dangerous lows, and give the pancreas a chance to recover. Some cats regain enough beta cell function to reach diabetic remission, meaning they no longer need insulin. In one large study of 185 cats treated with protamine zinc insulin, the remission probability was 56.2% [4]. Cats with lower mean blood glucose during treatment and lower mean insulin doses were more likely to go into remission [4]. ## ProZinc Dose for Cats: What Owners Need to Know ### Who decides the dose Your veterinarian decides the dose. Never adjust it on your own based on a single high or low reading at home. The starting dosage for cats with newly diagnosed diabetes is 0.25 U/kg (1 U/cat), injected under the skin every 12 hours [1]. Your veterinarian will then adjust the dose over weeks based on glucose curves, clinical signs, and your cat's weight. There is no universal ProZinc insulin for cats dosage chart that fits every cat. Doses are individualized. Some cats need more, some need less, and the correct amount can change over time as beta cell function shifts. A cat that needed 3 units last month may need 1 unit now. ### How it is given ProZinc is injected under the skin (subcutaneously), usually in the scruff, flank, or shoulder area. Most owners rotate injection sites to keep the tissue healthy. Give the injection right before or with a meal. With twice-daily injections, cats get two meals of equal calories, each one immediately before insulin administration [1]. If your cat does not eat, do not give the full dose without checking with your veterinarian first. Insulin without food can push blood glucose too low. ### What to do about a missed dose If you miss a dose, do not double up at the next injection. Call your veterinarian for instructions. In most cases, the advice is to skip the missed dose and resume the normal schedule, but your veterinarian needs to make that call based on your cat's numbers and how late the dose is. ### Syringes matter more than most owners realize ProZinc is a U-40 insulin. That means there are 40 units of insulin per milliliter. U-40 syringes are marked for U-40 insulin. U-100 syringes are marked for a more concentrated insulin and hold 100 units per milliliter. If you draw U-40 insulin into a U-100 syringe, you will give the wrong amount. Each insulin type has a specific syringe size, and it is vital that a cat owner uses the appropriate syringe for their cat's insulin [2]. Ask your veterinarian or pharmacist to confirm the syringe type every time you pick up a new box. If the box looks different from last time, stop and call before you inject. ## Common and Serious Side Effects | Side effect | How common or serious | What to do | |---|---|---| | Low blood glucose (hypoglycemia): weakness, wobbling, drooling, seizures | Serious, can be life threatening | If your cat is conscious and can swallow, rub a small amount of honey or syrup on the gums and call your veterinarian right away. If unconscious or seizing, go to an emergency clinic immediately. | | Injection site reactions: pain, swelling, hair loss | Uncommon, usually mild | Rotate sites and mention it at your next visit. Call if you see a lump that grows or does not go away. | | Poor control: increased drinking, urination, appetite, weight loss | Common when the dose is too low | These are signs the dose may need to increase. Track them and call your veterinarian. See our guide to [insulin underdose signs in cats](/knowledge/veterinary-medicine/senior-and-chronic-care/cat-diabetes-insulin-underdose-signs). | | Diabetic ketoacidosis: vomiting, lethargy, fast breathing, sweet-smelling breath | Serious, emergency | Go to an emergency clinic now. | | Somogyi effect (rebound high glucose after a low) | Uncommon, needs veterinary diagnosis | Do not increase the dose on your own. Your veterinarian needs a glucose curve to sort this out. | Some cats have other conditions that make diabetes harder to control. Obesity predisposes cats to insulin resistance [1]. So do hormonal diseases such as hyperadrenocorticism (Cushing's syndrome) [1]. If your cat has hyperthyroidism as well as diabetes, treatment of the thyroid disease can change insulin needs, so read our guide to [methimazole dosing and monitoring in cats](/knowledge/veterinary-medicine/calculators-clinical-tools/methimazole-cat-dose-feline-hyperthyroidism-dose-and-monitoring) and keep your veterinarian informed about all medications. ## Who Should Not Take ProZinc, and What Interacts With It ProZinc is not right for every diabetic cat. Your veterinarian will consider your cat's full health picture before prescribing it. Cats who should not receive ProZinc without careful veterinary review include: - Cats with a history of hypoglycemia on another insulin - Cats with uncontrolled infections, which can cause insulin resistance - Cats with ketoacidosis at diagnosis, which needs hospital treatment first - Cats with known hypersensitivity to protamine zinc insulin or its ingredients - Pregnant or nursing cats, since insulin needs change dramatically Drug interactions matter too. Glucocorticoids (steroids) and progestins can cause insulin resistance and secondary diabetes [1]. If your cat is on a steroid for another condition, tell your veterinarian. Recent pre-diabetic corticosteroid use was one factor linked to a lower chance of remission in cats treated with protamine zinc insulin [4]. Other medications that can affect blood glucose include some diuretics, certain antibiotics, and thyroid medications. Always tell your veterinarian about every drug, supplement, and topical product your cat receives. ## ProZinc Overdose: What to Do An insulin overdose can cause severe hypoglycemia. Signs include weakness, staggering, drooling, twitching, seizures, and collapse. These can appear within hours of the injection. If you think your cat received too much ProZinc: - If your cat is conscious and can swallow, put a small amount of corn syrup, honey, or sugar water on the gums. - Call your veterinarian or an emergency clinic immediately. - If your cat is unconscious, seizing, or cannot swallow, go to an emergency clinic now. Do not try to give anything by mouth. For poison-related questions, you can also call the ASPCA Animal Poison Control Center at (888) 426-4435 or the Pet Poison Helpline at (855) 764-7661. These services may charge a consultation fee. Do not wait to see if your cat "seems fine." Hypoglycemia can worsen quickly. ## Monitoring Your Cat at Home Home monitoring is what makes ProZinc dosing safe. Your veterinarian cannot see your cat every day, but you can. ### Glucose curves A glucose curve means checking blood glucose every 1 to 2 hours over a 12-hour period, usually starting just before the morning insulin dose. This shows your veterinarian how low the glucose drops and how long the insulin lasts. Many owners learn to do this at home with a pet glucose meter and a small prick of the ear. ### Continuous glucose monitors Some veterinarians place a continuous glucose monitor (CGM) that records glucose every few minutes for up to two weeks. This gives a much fuller picture than a single reading. In one recent case report, an automated insulin delivery system that combined a CGM with an insulin pump rapidly improved glycemic control in a cat and led to diabetic remission [5]. That technology is not yet standard for cats, but CGMs themselves are increasingly common. ### What to track between curves - Water intake and urine output - Appetite and food intake - Weight, weekly if possible - Energy level and grooming - Any vomiting, diarrhea, or lethargy Bring these notes to every recheck. Your veterinarian will use them along with glucose curves and possibly a fructosamine test to decide whether to adjust the dose. ### Diet A low-carbohydrate diet is often part of the plan. In the 185-cat study, a low-carbohydrate diet was significantly associated with increased survival time [4]. Ask your veterinarian what diet fits your cat's other health needs. ## Limitations and When to Contact a Veterinarian No article can tell you the right dose for your cat. Every cat's insulin needs are individual, and only your veterinarian can evaluate your cat's glucose data, weight, diet, and other conditions together. Contact your veterinarian the same day if: - Your cat refuses to eat before an insulin dose - You see one or two readings that are much lower than usual - Your cat vomits once or twice but seems otherwise stable - You are unsure whether a dose was given Go to an emergency clinic now if: - Your cat is weak, wobbly, drooling, twitching, or seizing - Your cat is vomiting repeatedly, very lethargic, or breathing fast - Your cat's breath smells sweet or fruity - Your cat collapses or cannot stand Schedule a routine visit if: - Home glucose readings are consistently high for several days - Your cat is drinking and urinating more than usual - Your cat is losing weight despite eating well - You notice a lump or sore at an injection site ## Frequently Asked Questions ### Can I use U-100 syringes with ProZinc? No. ProZinc is a U-40 insulin, so it must be drawn into U-40 syringes. Using the wrong syringe will give an incorrect dose and could cause dangerous hypoglycemia or poor control [2]. ### Can ProZinc put my cat into remission? Remission is possible. In one study of 185 cats treated with protamine zinc insulin, the remission probability was 56.2% [4]. Cats with lower mean blood glucose during treatment and lower mean insulin doses were more likely to reach remission [4]. ### Should I feed my cat before or after the insulin injection? Feed right before or with the injection. With twice-daily dosing, cats get two meals of equal calories, each one immediately before insulin administration [1]. If your cat will not eat, call your veterinarian before giving the dose. ### How often does my cat need a glucose curve? Your veterinarian will set the schedule, often every 1 to 2 weeks while the dose is being adjusted, then less often once control is stable. Some cats use a continuous glucose monitor instead, which records readings around the clock [5]. ### What if my cat's blood sugar is high even on ProZinc? Persistent high glucose can mean the dose is too low, the insulin is not lasting long enough, or another condition is interfering. Obesity and hormonal diseases such as hyperadrenocorticism both cause insulin resistance in cats [1]. Your veterinarian may recommend a different insulin, a dose change, or testing for other diseases. Do not increase the dose on your own. ## Related Articles - [Insulin Glargine for Cats: Feline Diabetes Dose and Glucose Curve](/knowledge/veterinary-medicine/calculators-clinical-tools/insulin-glargine-for-cats-feline-diabetes-dose-and-glucose-curve) - [Cat Diabetes: How to Tell If Your Cat's Insulin Dose Is Too Low](/knowledge/veterinary-medicine/senior-and-chronic-care/cat-diabetes-insulin-underdose-signs) - [Methimazole Cat Dose: Feline Hyperthyroidism Dose and Monitoring](/knowledge/veterinary-medicine/calculators-clinical-tools/methimazole-cat-dose-feline-hyperthyroidism-dose-and-monitoring) - [Onsior Robenacoxib for Cats: Feline NSAID Safe Dosing Protocol](/knowledge/veterinary-medicine/calculators-clinical-tools/onsior-robenacoxib-for-cats-feline-nsaid-safe-dosing-protocol) - [Vitamin B12 Injections for Cats: Cobalamin Deficiency and Dosing Schedule](/knowledge/veterinary-medicine/nutrition/vitamin-b12-injections-for-cats-cobalamin-deficiency-and-dosing-schedule) - [Revolution Plus for Cats: Selamectin Sarolaner Feline Dose Guide](/knowledge/veterinary-medicine/calculators-clinical-tools/revolution-plus-for-cats-selamectin-sarolaner-feline-dose-guide) ## References 1. [Diabetes Mellitus in Dogs and Cats - Endocrine System](https://www.merckvetmanual.com/endocrine-system/the-pancreas/diabetes-mellitus-in-dogs-and-cats). Merck Veterinary Manual. 2. [Feline Diabetes](https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/feline-diabetes). Cornell University College of Veterinary Medicine. 3. [Insulin Therapy in Small Animals, Part 2: Cats](https://pubmed.ncbi.nlm.nih.gov/36906468/). The Veterinary clinics of North America. Small animal practice, 2023. 4. [Loose-control of diabetes mellitus with protamine zinc insulin in cats: 185 cases (2005-2015)](https://pubmed.ncbi.nlm.nih.gov/30992596/). The Canadian veterinary journal = La revue veterinaire canadienne, 2019. 5. [Use of an automated insulin delivery system in a cat with diabetes mellitus](https://pubmed.ncbi.nlm.nih.gov/41742542/). Journal of veterinary internal medicine, 2026. ## Further Reading - [American Veterinary Medical Association: First Aid Tips for Pet Owners](https://www.avma.org/resources-tools/pet-owners/emergencycare/first-aid-tips-pet-owners) - [Merck Veterinary Manual: Cat Owners](https://www.merckvetmanual.com/cat-owners) - [Cornell Feline Health Center: Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information)