Iletin from Eli Lilly. Beef R/Neutral in varying strengths--not highly purified, nor were there any suspension insulins at the time. Photo is likely ca. 1922-1923.

Eli Lilly's brand name for the beef, beef/pork[1], and pork insulins it formerly produced. When the company began producing insulin in 1922, it called its insulin derived from bovine pancreas Iletin[2][3][4][5]. Eli Lily announced the discontinuation[6] of the last of its natural Iletin insulins in July 2005.

Iletin I beef/pork insulins in Regular/Neutral, NPH/Isophane and Lente types. The insulin was discontinued by Lilly in 1998.


  1. Iletin Beef/Pork in R/Neutral, NPH/Isophane & Lente Types-Discontinued in 1999
  2. Iletin Carton-1922
  3. Iletin Vial & 2 Cartons-Left is U20, Right is U40 Insulin
  4. Closer View of 1923 Iletin Vial
  5. Iletin--1950 Medical Journal Ad--All Beef-U40 in Front-Likely U80 in Rear.
    At the time, only R/Neutral, NPH/Isophane and Protamine Zinc/PZI types were marketed
  6. Lilly Discontinues Iletin II R & Iletin II N
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