Insulin glargine is a long-acting synthetic insulin analog widely used to manage diabetes mellitus in cats. Originally developed for human medicine under the brand name Lantus, insulin glargine has become one of the most popular insulin choices in feline diabetology due to its smooth, prolonged duration of action and relatively high remission rates in cats when initiated early after diagnosis.
Overview
Unlike intermediate-acting insulins such as NPH, insulin glargine forms micro-precipitates when injected subcutaneously at physiological pH, resulting in a slow and relatively peakless release of insulin over an extended period. In cats, insulin glargine typically provides 12 to 24 hours of glycemic control, making it well suited for twice-daily dosing protocols. Studies have shown that cats started on glargine early in the course of diabetes, combined with a low-carbohydrate diet, may achieve diabetic remission rates of 80 percent or higher.
Uses
Insulin glargine is prescribed for the management of diabetes mellitus in cats and dogs. Common clinical scenarios include:
- Newly diagnosed feline diabetes mellitus — Glargine is often the first-line insulin choice for cats due to its favorable pharmacokinetics and association with higher remission rates.
- Cats not well controlled on other insulins — Cats that exhibit poor regulation on ProZinc or other insulin types may be transitioned to glargine.
- Canine diabetes mellitus — Used off-label in dogs, though veterinary-labeled insulins (Vetsulin) are more commonly selected for dogs.
Dosage
Insulin glargine dosing is highly individualized. Your veterinarian will determine the appropriate starting dose and adjust based on blood glucose curves.
| Parameter | Detail |
|---|---|
| Starting dose (cats) | 0.25–0.5 U/kg subcutaneously every 12 hours |
| Typical maintenance | 0.5–2 U per cat every 12 hours |
| Route | Subcutaneous injection |
| Frequency | Every 12 hours (twice daily) |
| Monitoring | Blood glucose curves, fructosamine levels |
Important dosing notes:
- Never shake the insulin vial; gently roll it between your palms to mix.
- Use U-100 insulin syringes matched to the concentration of glargine (100 U/mL).
- Dose adjustments should only be made by your veterinarian based on serial blood glucose measurements.
- If your cat stops eating, contact your veterinarian before giving the next insulin dose.
- Some cats achieve remission (no longer need insulin). Watch for signs of hypoglycemia, which may signal remission.
Side Effects
| Common Side Effects | Serious Side Effects (Contact Your Vet Immediately) |
|---|---|
| Mild discomfort at injection site | Hypoglycemia (weakness, trembling, wobbling, seizures, collapse) |
| Transient appetite changes during regulation | Diabetic ketoacidosis (vomiting, lethargy, acetone-smelling breath) |
| Weight gain as diabetes is controlled | Somogyi effect (rebound hyperglycemia from excessive insulin) |
Hypoglycemia is the most dangerous complication of insulin therapy. If your cat shows signs of low blood sugar (stumbling, disorientation, tremors, seizures), rub corn syrup or sugar water on the gums immediately and contact your veterinarian or emergency clinic.
Drug Interactions
- Corticosteroids (prednisolone, dexamethasone): Cause insulin resistance and may worsen diabetes control.
- Progestins (megestrol acetate): Can induce or worsen diabetes in cats.
- Other hypoglycemic agents: Combining insulin with oral hypoglycemics may increase hypoglycemia risk.
- Thyroid medications: Treating concurrent hyperthyroidism may alter insulin requirements.
Always inform your veterinarian of all medications and supplements your cat receives.
Contraindications
- Do not use during active hypoglycemic episodes.
- Use with caution in cats with concurrent liver or kidney disease, as insulin metabolism may be altered.
- Do not use insulin that has been frozen or exposed to excessive heat.
- The safety of insulin glargine has not been fully evaluated in pregnant or lactating cats.
Storage
- Store unopened vials in the refrigerator (36–46 degrees F / 2–8 degrees C).
- Once opened, the vial may be stored at room temperature or refrigerated and should be used within 28 days.
- Do not freeze insulin glargine.
- Protect from direct sunlight and heat.
- Discard if the solution appears cloudy, discolored, or contains particles.
FAQ
Q: Why is insulin glargine preferred over other insulins for cats? A: Glargine provides a smooth, relatively peakless insulin profile in cats, which closely mimics natural insulin secretion. Studies have shown higher diabetic remission rates in cats treated with glargine compared to some other insulin types, particularly when combined with a low-carbohydrate diet.
Q: Can my diabetic cat go into remission on glargine? A: Yes. Some cats, especially those diagnosed early and started promptly on glargine with dietary management, can achieve remission where they no longer require insulin injections. Your veterinarian will monitor for signs of remission through glucose curves and clinical assessment.
Q: How do I perform a blood glucose curve at home? A: Your veterinarian may recommend home glucose monitoring using a pet glucometer or continuous glucose monitor. Blood glucose is typically measured every 2 hours over a 12-hour period to assess how the insulin is working. Follow your veterinarian’s specific instructions for timing and technique.
Q: Is Lantus the same as Basaglar or Semglee? A: Basaglar and Semglee are biosimilar insulin glargine products. They contain the same active ingredient at the same concentration (100 U/mL). Many veterinarians consider them interchangeable with Lantus, but discuss any product switches with your veterinarian.
This content is for informational purposes only and is not a substitute for professional veterinary advice. Always consult your veterinarian before starting, changing, or stopping any medication for your cat.