Insulin (Glargine, PZI, NPH/Lente, Detemir)

What is this medication for?

• Diabetes mellitus (uncomplicated and DKA), adjunct for severe hyperkalemia

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

• Never abbreviate "Units" as "U" on any written instruction — well-documented source of 10x dosing errors.
• Glargine currently has the strongest evidence for diabetic remission in cats — often preferred first-line for feline diabetes alongside dietary changes (low-carb, high-protein).

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• Insulin-induced hyperglycemia ("Somogyi effect") (Possible with overdosing)
• Insulin resistance/antibody formation (Higher with beef/pork sources (~45% dogs) vs. human recombinant (~5%))
• Injection site stinging (glargine specifically, low pH ~4) (Mild)
• Lipodystrophy (With repeated same-site injection)

Worth a phone call to your veterinarian

• Any new symptom that worries you.

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Hypoglycemia (Primary risk of any insulin therapy)

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Active hypoglycemia

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • Glucocorticoids
  • Beta-blockers
  • ACE inhibitors, aspirin, MAOIs, alcohol
  • Thiazides, corticosteroids, thyroid hormone

Storage and handling

Refrigerate; do not freeze; warm gently and roll (don't shake) before drawing up a dose. Do not use compounded insulin products from compounding pharmacies — documented unreliable potency.

Good to know

• Never abbreviate "Units" as "U" on any written instruction — well-documented source of 10x dosing errors.
• Glargine currently has the strongest evidence for diabetic remission in cats — often preferred first-line for feline diabetes alongside dietary changes (low-carb, high-protein).
• Dog vs. cat insulin choice differs substantially — NPH/Lente works reasonably in dogs but has too short a duration to be reliable in most cats; PZI, glargine, or detemir are generally preferred for cats.
• Confirm syringe type (U-40 vs. U-100) matches the product concentration every time — a leading source of dangerous dosing errors when owners switch products.