Lantus, Levemir, Basaglar & Semglee: What Cat Owners Should Know
If your cat has been prescribed a long-acting insulin like Lantus or Levemir (or biosimilars like Basaglar or Semglee), here's a clear breakdown of how they’re packaged, how to use them safely, and what to watch out for.Lantus & Levemir: What's the Difference?
Packaging Options
Lantus (glargine):- 10 mL vial
- 3 mL prefilled SoloStar pens (box of 5)
- Refill cartridges (discontinued in the U.S.)
- 3 mL KwikPens (box of 5)
- Cartridges (not sold in the U.S.)
- No 10 mL vial available
- 10 mL vial
- 3 mL prefilled pens (box of 5)
- Not yet available in all countries
- 10 mL vial
- 3 mL FlexTouch pens (box of 5)
- Refill cartridges (no longer in U.S.)
Storage and Handling
- Store unopened insulin in the fridge (36–46°F / 2–8°C).
- Keep it upright and don’t freeze it.
- Check for clarity—insulin should be clear and colorless.
- Never shake or roll vials or pens.
- Don’t inject air into pens or cartridges.
- Avoid drawing excess insulin back into the container—it can contaminate it.
About Repackaged Insulin
Insulin should come in sealed packaging directly from the manufacturer. If your vet provides insulin in an unsealed or transferred container, know that stability and sterility may be compromised.
Shelf Life: Manufacturer vs. Real-World Use
| Insulin | Manufacturer Shelf Life | Real-World Reports |
|---|---|---|
| Lantus/Basaglar | 28 days after opening | Often lasts 4–6+ months with care |
| Semglee | 28 days (limited data) | Expected similar to Lantus |
| Levemir | 42 days after opening | Often lasts 4–6+ months with care |
Dosing Tools & Techniques
Syringes:- Use U-100 3/10cc syringes with half-unit markings for precision.
- Brands like BD Ultra-Fine, Monoject, UltiCare Vet Rx, and ReliOn are popular.
- Needle lengths: 6mm, 8mm, or 12.7mm.
- Gauge: 29–31G (31G is the thinnest and least painful).
- All listed pens deliver insulin in whole units only.
- Accurate for human use, but less practical for cats needing micro-doses.
- We recommend using a syringe to draw insulin from pens so you can dose in 0.25 or 0.5 unit increments.
- If using the pen with needle:
- Prime before each shot (wastes insulin).
- Hold for 5–10 seconds after injection to ensure full delivery.
- Manufacturers advise against refrigerating in-use pens, but many cat caregivers do with no issue.
Tiny Doses? Use the Fine-Dose Guide
When micro-dosing (e.g., 0.1 to 0.5 units), reference a visual dose guide and learn how to read your syringe markings precisely. Some members use a "fat" or "skinny" notation to fine-tune these doses.Pictures, videos, and more informational links are available here. Insulin Care & Syringe Info: Proper Handling, Drawing, Fine Dosing.
Injection Sites
- Most common sites: flank, belly, or scruff.
- Flank and belly often provide better absorption than the scruff.
- Rotate injection areas to avoid scar tissue or poor absorption zones.
Final Notes
- Don't panic if insulin is left out for a few hours—most modern insulins are more stable than we once thought.
- If regulation suddenly disappears with no obvious reason, it may be time to replace your insulin.
- Always check with your vet before making any changes, especially regarding dilution, storage, or syringe type.
Pictures, videos, and more informational links are available here. Insulin Care & Syringe Info: Proper Handling, Drawing, Fine Dosing.
-Tim
Change Log:
Created on 5/18/2025.
Sources:
Jill & Alex (GA). "Insulin Care & Syringe Info: Proper Handling, Drawing, Fine Dosing." Feline Diabetes Message Board, 29 Dec. 2009, Sticky - Insulin Care & Syringe Info: Proper Handling, Drawing, Fine Dosing | Feline Diabetes Message Board - FDMB.