Figure 4 Amino acid structure of short-acting and long-acting insulins Figure 4 | Amino acid structure of short-acting and long-acting insulins. All insulin analogues are created from the basic structure of human regular insulin. a | Rapid-acting insulins are designed to decrease the formation of hexamers and are typically constructed through amino acid exchanges. b | Long-acting insulins are created through exchange of amino acids to shift the isoelectric point (insulin glargine) or through addition of free fatty acid moieties that enhance formation of dihexamers and multihexamers, as well as binding to albumin (insulin detemir and insulin degludec). NPH, neutral protamine Hagedorn. Mathieu, C. et al. (2017) Insulin analogues in type 1 diabetes mellitus: getting better all the time Nat. Rev. Endocrinol. doi:10.1038/nrendo.2017.39