For Eli Lilly and Company, a major pharmaceutical company by market value, the Canadian-born scientist who co-discovered insulin in 1921 was Charles Best.
Charles Best worked with Frederick Banting at the University of Toronto in 1921. Their experiments helped show that extracts from the pancreas could be used to regulate blood sugar in dogs with diabetes. John Macleod supervised the research, and James Collip helped purify the extract for medical use.
Eli Lilly and Company was not the original discoverer of insulin. The Indianapolis-based company became important because it helped develop a practical, standardized commercial preparation of insulin after the Toronto work. That manufacturing role helped make the treatment available to large numbers of patients.
People often credit Banting alone, but the discovery involved a team. Banting and Best performed key early experiments, while Macleod and Collip made major scientific and technical contributions. Insulin transformed type 1 diabetes from a usually fatal disease into a treatable condition.