Table 1.  Receptor binding, biological activity and serum half‐life of three abnormal insulins.

	Normal Human	Chicago LeuB25	Los Angeles SerB24	Wakayama LeuA3
In vitro receptor binding (%)	100	2.0–2.8	0.5–1.8	0.3–0.7
Biological activity (%)	100	1.9–2.5	0.6–1.5	0.4–0.8
In vivo serum half‐life in dog (min)	3.6	15.0	24.5	35.0

Human Insulin served as standard and was defined as 100% receptor binding and biological activity. Receptor binding was determined by using rat adipocytes, and biological activity was assessed by the stimulation of glucose uptake or oxidation in rat adipocytes. In vivo half‐life was determined by using somatostatin infused dog.