Major Uses

Metformin is an antihyperglycemic that works by increasing the insulin sensitivity of tissue. It is used in the treatment of non-insulin dependent diabetes mellitus in cats, and it is often used in combination with other medications. This drug does not stimulate the production of insulin or the release of insulin from the pancreas.

Metformin is only available in preparations for humans, but it is often used to control insulin levels in cats.

Common Precautions

Although metformin does not cause low blood sugar, it may cause vomiting, appetite loss, weight loss, and lethargy in cats. These side effects are uncommon, but they have been observed.

This drug is not safe for use in cats with kidney insufficiency, any form of acidosis, or in cats that are scheduled for an iodine-containing radiographic contrast agent within the next few days. Metformin should be used cautiously in nursing mothers.

Metformin may interact with ACE inhibitors, corticosteroids, thiazide, sympathomimetic agents, ranitidine, furosemide, trimethoprim, cimetidine, digoxin, and other drugs. Metformin should not be used in animals with a known allergy or hypersensitivity to the drug. Overdose of metformin may cause vomiting and diarrhea in dogs. Lactic acidosis is also a possible, although no cases have been reported in cats. Any known or suspected overdose should be reported to a veterinarian right away.


Metformin should be stored away from light, in its original packaging, and at room temperature. This drug should be kept out of the reach of children and animals.


Metformin is available in tablet form and as an oral solution.

In cats, the typical dose of metformin is 50 mg per cat by mouth twice daily. Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

If a dose of metformin is missed, it should be taken as soon as possible. If it is nearly time for the next scheduled dose of the medication, the missed dose should be skipped and the regular schedule should be resumed. Two doses of this medication should not be taken at the same time.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.