The primary treatment for diabetes in dogs is insulin injections, usually administered twice daily in conjunction with meals. Dog insulin is almost exactly the same molecule as porcine (pig) insulin, so that is usually what is used. Unfortunately, for dogs, there is no alternative to injectable insulin (for diabetic humans and diabetic cats, there is an alternative).
The Cost of Insulin for Dogs
Insulin is not inexpensive. The American College of Veterinary Pharmacists estimates that insulin for a large dog could run $150 per month, saying costs have tripled since 2002.
The FDA-approved insulin for dogs is Vetsulin, which comes in a 10 mL vial  and require syringes specific for insulin of this strength (40 units/mL). A VetPen (insulin pen) is available with 2.7 mL cartridges.
The average cost of Vetsulin is $70/10 mL vial or $230/10 – 2.7 mL cartridges (the VetPen starter kit is about $180).
How long a vial or cartridge lasts depends on the individual patient, with larger dogs generally needing more insulin per dose. The choice of which insulin to treat a diabetic dog is determined by the dog’s veterinarian.
Do Not Swap Insulin Types
While it is possible to use an insulin labeled for humans, it isn’t likely to save you much money. Humulin-N (100 units/mL) can range in price from $100 to 170 for a 10 mL vial. Critical note: Humulin-N is a different concentration from Vetsulin and requires different syringes for administration; do not just swap insulin out without checking with your veterinarian.
A proper diabetic diet can help decrease a dog’s insulin requirements, but dogs do not go into remission based on dietary therapy alone.
Diabetes mellitus is a hormone deficiency that leaves a dog unable to regulate his blood glucose (sugar) properly. This can result in clinical symptoms that include increased drinking, increased urination, weight loss, cataracts, and other metabolic abnormalities that can result in severe illness and death.
The primary problem is a lack of insulin. Insulin is a hormone produced by the pancreas. Normally, the pancreas releases insulin into the bloodstream to control the use of glucose, the preferred form of fuel used by the cells of the body. Without insulin, the cells cannot access to glucose in the bloodstream, and that glucose, which comes from digested carbohydrates or released from storage within the body, builds up to abnormally high levels that can damage the dog’s other organs.
