Understanding the Insulin Depot: An Overview
You may have seen references to something called the "insulin depot" when discussing Lantus, Levemir, or the glargine biosimilars (such as Basaglar and Semglee). But what does that actually mean?
While these insulins aren't "true" depot drugs like long-acting hormonal therapies, they behave similarly by being absorbed gradually.
Try to see your spreadsheet as a series of waves rather than isolated cycles.
Understanding the insulin depot can help explain why your cat's numbers might fluctuate even when nothing seems to have changed. Being aware of this effect can help you make better-informed decisions and recognize when to wait things out versus when to take action.
- Tim
Change Log:
Created on 5/19/2025. Next step is proof read to ensure proper wording and add more detail.
Sources:
Lindauer, Klaus, and Reinhard Becker. "Insulin Depot Absorption Modeling and Pharmacokinetic Simulation with Insulin Glargine 300 U/mL." International Journal of Clinical Pharmacology and Therapeutics, vol. 57, no. 1, Jan. 2019, pp. 1–10. PubMed
Gradel, Anna Katrina Jógvansdóttir, et al. "Factors Affecting the Absorption of Subcutaneously Administered Insulin: Effect on Variability." Journal of Diabetes Research, vol. 2018, Article ID 1205121, 2018. PMC+5Københavns Universitets Forskningsportal+5ucviden.dk+5
Wright, Jeremy C., and Diane J. Burgess. Long Acting Injections and Implants. Springer, 2012.Wikipedia+1PubMed+1
"Depot Injection." Wikipedia, Wikimedia Foundation, Depot injection - Wikipedia.
Jill & Alex (GA). "Sticky - What Is the Insulin Depot?" Feline Diabetes Message Board, 28 Dec. 2009, Sticky - What is the Insulin Depot? | Feline Diabetes Message Board - FDMB.
You may have seen references to something called the "insulin depot" when discussing Lantus, Levemir, or the glargine biosimilars (such as Basaglar and Semglee). But what does that actually mean?
What is a Depot?
In general terms, a "depot" refers to a substance stored in the body and released over time. In the case of insulin, it means that after you inject a long-acting insulin like Lantus or Levemir, a small reservoir of insulin forms under the skin. This reservoir slowly releases insulin into the bloodstream over an extended period, contributing to a smoother, flatter blood glucose curve.While these insulins aren't "true" depot drugs like long-acting hormonal therapies, they behave similarly by being absorbed gradually.
How the Depot Works
- Lantus and Biosimilars (Glargine): After injection, the solution reacts with the body’s neutral pH, forming crystals that slowly dissolve, releasing insulin steadily over time.
- Levemir (Detemir): This insulin doesn’t form crystals. Instead, it clumps together at the injection site and binds to proteins in the blood (albumin), which helps it release more slowly.
Why the Depot Matters
Because these insulins build up a small reservoir in the body, what happens during one cycle can influence several future cycles. For example:- Missed or reduced dose? You may see higher BGs for a few days while the depot rebuilds.
- Dose increase? The depot may take time to stabilize, so changes in BG might lag.
- Dose decrease? You might see unexpectedly low numbers as the excess insulin stored in the depot is still being released.
How Long Does It Take to Adjust?
Experience from caregivers shows that the depot can influence BGs for up to six cycles (about three days). The duration may be shorter with smaller doses and longer with larger ones.
Understanding the Bigger Picture
Don’t get too caught up in individual readings. Instead, look at patterns over several days. If numbers seem inconsistent, consider what happened earlier in the week — any skipped doses, food changes, illness, or stress?Try to see your spreadsheet as a series of waves rather than isolated cycles.
What's NOT the Depot
The insulin depot is different from:- Carryover: When insulin continues to work beyond its typical duration.
- Overlap: When one dose is still active as the next dose is beginning.
Sources for Further Learning
- Insulin Detemir and its Unique Mechanism of Action - Internet Journal of Endocrinology
- Textbook of Diabetes Mellitus - B. B. Tripathy
- Mechanism of Protraction of Insulin Detemir - National Library of Medicine
Understanding the insulin depot can help explain why your cat's numbers might fluctuate even when nothing seems to have changed. Being aware of this effect can help you make better-informed decisions and recognize when to wait things out versus when to take action.
- Tim
Change Log:
Created on 5/19/2025. Next step is proof read to ensure proper wording and add more detail.
Sources:
Lindauer, Klaus, and Reinhard Becker. "Insulin Depot Absorption Modeling and Pharmacokinetic Simulation with Insulin Glargine 300 U/mL." International Journal of Clinical Pharmacology and Therapeutics, vol. 57, no. 1, Jan. 2019, pp. 1–10. PubMed
Gradel, Anna Katrina Jógvansdóttir, et al. "Factors Affecting the Absorption of Subcutaneously Administered Insulin: Effect on Variability." Journal of Diabetes Research, vol. 2018, Article ID 1205121, 2018. PMC+5Københavns Universitets Forskningsportal+5ucviden.dk+5
Wright, Jeremy C., and Diane J. Burgess. Long Acting Injections and Implants. Springer, 2012.Wikipedia+1PubMed+1
"Depot Injection." Wikipedia, Wikimedia Foundation, Depot injection - Wikipedia.
Jill & Alex (GA). "Sticky - What Is the Insulin Depot?" Feline Diabetes Message Board, 28 Dec. 2009, Sticky - What is the Insulin Depot? | Feline Diabetes Message Board - FDMB.