insulin glar·gine (glär?j?n?)n. A long-acting insulin analog whose amino acid sequence differs from that of human insulin by the substitution of glycine for asparagine at one end of the A chain and the addition of two arginines to the B chain, used in the treatment of type 1 and type 2 diabetes.[gl(ycine) + arg(inin)ine.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.