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 twice a day. Two veterinary insulins are approved, and several human insulins are used routinely under a vet’s direction; which one, and from where, makes a large difference to what an owner pays.
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 recognise low blood sugar and to keep feeding and injection times consistent.
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 human insulins 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 last well beyond its in-use period before it is used up; vials or smaller pens are sometimes more economical.
Why the cash price varies
The veterinary insulins are sold through vets and veterinary pharmacies. The human insulins sit in the same market as for people: a brand such as Lantus, the same manufacturer’s unbranded version, and biosimilars are the same insulin at very different list prices, and a prescription written generically lets the pharmacy dispense the cheapest. Manufacturer self-pay programmes for human insulins generally apply to people, not pets, so pharmacy comparison matters more for an animal.
How to pay less
- If your vet prescribes a human insulin, ask for the prescription to be written generically with substitution allowed.
- Ask the pharmacy which versions of that insulin it can order and the cash price of each.
- Ask the vet whether vials would be more economical than pens for your pet’s dose.
- 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 recognise 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?
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\u2019s 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.