In 1921 the Canadian investigators Banting and Best discovered in experiments with diabetic dogs that a pancreatic extract - insulin - effectively lowered the blood sugar level. As early as 1922 the first diabetic patient was successfully treated with the hormone extract. Since then management of diabetes without insulin is unimaginable. In the meantime insulin analogues are available in addition to human insulin. Targeted treatment with insulin enables the patient to enjoy a good quality of life including improved physical fitness when a few general conditions are met.