Insulin for diabetic pets
Vetsulin (porcine, veterinary) · ProZinc (veterinary) · Lantus, Basaglar, Semglee (insulin glargine, human) · Humulin N, Novolin N (NPH, human)
Diabetic dogs and cats are treated with insulin injections, once or twice a day as the vet directs. Veterinary insulins are approved for both species, and several human insulins are used routinely under a vet’s direction; which one is used is the vet’s decision.
What it is used for
Diabetes in dogs is usually lifelong and insulin-dependent; in cats, early treatment with a long-acting insulin and a low-carbohydrate diet can lead to remission. Vetsulin (porcine lente) and ProZinc (protamine zinc) are the FDA-approved veterinary insulins. Human insulins are used off-label: NPH (Humulin N, Novolin N) in dogs, and insulin glargine (Lantus and its biosimilars) in cats, where it is often the first choice, and sometimes in dogs.
The vet sets the starting dose and adjusts it against blood glucose curves or a continuous glucose monitor. Owners learn to inject, to recognize low blood sugar and to keep feeding and injection times consistent.
Giving it to your pet
- How to give it
- Once or twice a day as your vet directs, with or just after a meal so you can confirm your pet has eaten; twice-daily doses are given about 12 hours apart. Use only the matching syringe: U-40 syringes for U-40 veterinary insulins, U-100 syringes for U-100 insulins. Mix exactly as your insulin’s label directs; some are shaken and others gently rolled.
- If you miss a dose
- Never give extra to make up a missed or uncertain dose; skip it and give the next dose at the usual time. If your pet does not eat, call your vet before giving the full dose.
- Storage
- In the refrigerator, never frozen, and not in the door, where the temperature swings. Discard opened vials or pens when the label says.
- Call your vet if you see
- Low blood sugar is the emergency to know: weakness, wobbliness, twitching, confusion or seizures. Rub a little corn syrup or honey on the gums and call your vet or an emergency clinic straight away.
Your vet’s instructions and the label on your pet’s medicine take priority over this general information.
Safety points that differ from human use
- Low blood sugar (weakness, wobbliness, seizures) is the emergency; the vet will explain what to give and when to go in.
- Veterinary insulins are U-40 and the human insulins named here are U-100: the syringes are different and using the wrong syringe gives the wrong dose. Always match the syringe to the insulin.
- Never change the insulin brand or type without the vet; they are not interchangeable unit for unit.
- Keep insulin refrigerated and discard it as the label directs; pens and vials have different in-use periods.
- Vials (veterinary and human)
- Pens and cartridges (veterinary and human)
- Veterinary insulins 40 units per mL
- Human insulins 100 units per mL
Pet doses are small, so a human pen may reach the end of its in-use period before it is used up; the vet can say whether a vial or a pen suits the dose.
Why the cash price varies
The veterinary insulins are sold through vets and pharmacies that carry veterinary products. The human insulins are filled at a licensed pharmacy on the vet’s prescription, and some come in brand, unbranded and biosimilar versions; whether the prescription may allow a version other than the one named is the vet’s decision. Each pharmacy sets its own cash price, so quotes for the same insulin prescription can differ.
Upload it and licensed pharmacies reply with their own cash price. You pay the pharmacy, not us.
How to pay less
- If your vet prescribes a human insulin, ask whether the prescription can allow substitution between versions of the same insulin.
- Ask the pharmacy which versions of that insulin it can order and the cash price of each.
- Ask the vet whether a vial or a pen better suits your pet’s dose.
- If the pharmacy can supply only a different version, the pharmacist may contact your vet; never switch insulins without the vet.
- Upload the prescription to Script Unlock so licensed pharmacies can quote the versions they stock. You pay the pharmacy directly.
Questions for your vet
- Which insulin, and are there equivalent versions the pharmacy could dispense?
- Which syringes match this insulin exactly?
- How do I recognize and treat low blood sugar at home?
- How will the dose be adjusted, and should we use a continuous glucose monitor?
- For a cat, is remission a realistic goal, and what diet goes with the insulin?
The same medicine is prescribed for people: see the Insulin guide for how it is supplied and priced at pharmacies.
Rules on refills, transfers and controlled substances differ by state; see pharmacy rules by state.
How Script Unlock gets you a cash price for your pet’s insulin for diabetic pets prescription
Prices on this site come from pharmacies responding to a real prescription. We do not publish estimated, average or "typical" prices, because none of those would be your price.
- 1You upload your prescription
A photo of your your pet’s insulin for diabetic pets prescription prescription is enough. Nothing is sold on the site; you are asking pharmacies to quote.
- 2Licensed pharmacies respond
Pharmacies that Script Unlock has verified see the request and each can reply with its own cash price for your exact drug, strength and quantity.
- 3You choose and pay the pharmacy
You compare the responses, pick a pharmacy, and pay that pharmacy directly when you collect. Script Unlock never takes a patient payment and never sets the price.
Related pet medications
Sources
- FDA Approved Animal Drug Products (Green Book)
- FDA Center for Veterinary Medicine
- Merck Veterinary Manual
- MedlinePlus drug information (National Library of Medicine)
Written by the Script Unlock editorial team from the sources above. Not yet reviewed by a veterinarian or veterinary pharmacist. Last checked 2026-10-03. Nothing here replaces your vet’s directions; doses for animals are set by weight and species.
Script Unlock is a marketplace that lets licensed pharmacies quote a cash price on your prescription. It does not prescribe, dispense or sell medication, does not process patient payments, and does not give medical advice. Always follow the instructions of your prescriber and pharmacist and read the medication guide supplied with your medicine.