Humulin L
Lente by Eli Lilly
intermediate-acting r-DNA/GE/GM
U100 Zinc
Line Humulin
Also known as N/A
Similar to  
Action in cats  
  • onset 2-5h,
  • peak 8-10h[1]
  • duration: 10-16h
Action in dogs  
  • onset 2-10h,
  • peak 6-24h,
  • duration 14-24h
Use and Handling
Type cloudy
Shelf Life 24 months
When opened 28 days
In pen N/A

Humulin L[2] was a U100 r-DNA/GE/GM intermediate-acting, lente insulin[3][4][5]. Novo Nordisk also made similar insulins, calling them Novolin L[6] and Monotard[7][8].

"L" came to an end when Eli Lilly announced in July, 2005 that it would no longer be produced[9][10]. The UK & Euro production of Humulin L stopped a year prior to this, in July 2004[11][12].

What Lente Is Not

No Lente-type insulin regardless of species can contain any NPH/isophane insulin[13] or any R/Neutral insulin[14][15].

Both are chemically impossible: the phenol preservative present in NPH/isophane alters the action of Lente-type insulins, creating a mixture with an approximate action of R/Neutral[16].

The zinc suspension of Lente-type insulin binds R/Neutral, causing the short-acting insulin to slow, losing its short-acting effect[17][18].

Lente-type insulins cannot be dispensed in pen or cartridge form because the glass ball used to mix the insulin in these devices will shatter the Lente crystals[19].

Combining Lente Family Insulins

None of the Lente family of insulins (semilente, Lente, Ultralente) can be combined with[20] NPH/isophane insulins. The phenol preservatives present in NPH-type insulins alters the Lente-types to the point where they become a close approximation of R/neutral, with regard to action[21].

Keeping the phenol preservatives in mind, all protamine-suspended insulin mixes would be "off limits" regarding same syringe mixing with any Lente-type insulins[22].

Insulin manufacturers[23] indicate that R/neutral and semilente, Lente, ultralente insulins are able to be combined in the same syringe, but only just before injection. In pre-filled syringes, the zinc suspension of the Lente-type insulins binds the R/neutral, causing it to lose its short-acting effect. Various studies have documented this, and some doctors advise against using R/neutral in the same syringe with the Lente family of insulins[24][25][26][27].

The Novo insulins,Monotard and Ultratard, were available slightly longer in Europe.

From the announcement: Monotard and Ultratard will not be available in the UK after February 2006. The discontinuation of these insulins was initially announced in September 2004. Initially the discontinuation was scheduled for February 2006, however this date has now been brought forward to October 2005.

Compared to Humulin N

Humulin L/Monotard and Humulin N are both U100 strength insulins of r-DNA/GE/GM species. They differ in their suspension. Humulin L and Monotard were Zinc suspended, from the Lente type family, while Humulin N/NPH insulins are isophane suspended.

Further Reading


See also Substitutes_for_Humulin_U_and_L.


  1. Insulins-North American Veterinary Conference-2005
  2. Humulin L carton photo.
  3. Humulin L, etc.-Lente Human Insulin
  4. Humulin L Patient Leaflet
  5. Humulin L Carton Photo
  6. US-FDA-Novolin L Discontinuation Notice-2003
  7. EMEA Scientific Discussion-Monotard
  8. Monotard Discontinuation Notice July 2005
  9. US-FDA-Humulin L Discontinuation Notice
  10. Lilly US Humulin L/Humulin U Discontinuation Sheet
  11. Withdrawal of EU/UK Humulin L July 2004
  12. Lilly EU/UK Product Sheet & Time Activity Profiles
  13. Combining Lente-type Insulins with Phenol-Preserved Insulins
  14. Lente Zinc Suspension Causes Loss Of R/Neutral Short-Acting Effect
  15. Availability of Soluble (R/Neutral) Insulin in Mixed Preparations With Crystalline (Lente) & Ultralente GE Insulin-Clinical Therapeutics-1991
  16. Lente-Type Insulins & NPH/Isophane Insulins-A Bad Combination
  17. Intermediate-Acting Insulin Preparations: NPH (Isophane) & Lente Diabetes Care-1980
    Note--in 1980, there was only beef Lente-type insulin--no pork or r-DNA/GE/GMLente insulins
  18. Resource Guide 2005-American Diabetes Association
  19. Insulin-Dependent Diabetes--Page 10--Dr. Ragnar Hanas
  20. Phenol Preservatives & Lente-type Insulins--A Bad Combination
  21. Therapy-Mixing Precautions
  22. Therapy-Mixing Precautions
  23. Insulin Producers vs Doctors Re:Combining R/Neutral & Lente-type Insulins
  24. Availability of Soluble (R/Neutral) Insulin in Mixed Preparations of Crystalline (Lente) & Ultralente GE Insulins-Clinical Therapeutics-1991
  25. Absorption Kinetics & Action Profiles-Single Subcutaneous Administration of Human Soluble (R/Neutral) & Lente Insulin-Diabetes Care-1987
  26. Delayed Onset of Action of Soluble (R/Neutral) Insulin After Premixing With Lente Insulin Diabetes Research & Clinical Practice-1983
  27. Therapy-Mixing Precautions
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