In Britain one person in every hundred is a diabetic and knows it. A further one in a hundred is a diabetic and doesn't know it - yet. Diabetes appears to run in families yet two thirds of all diabetics report no previous family history. Although it's one of the oldest diseases known to man its cause remains a mystery.

Until 1921 diabetes was a painful killer - often within a few weeks in children, usually within two years in adults. Then, nearly 50 years ago, two young Canadian scientists, Frederick Banting and Charles Best, made one of the most dramatic discoveries in the whole history of medicine. They isolated a substance called Insulin which today keeps some ten million diabetics alive. In the programme Dr Charles Best, now aged 70, describes that dramatic discovery. Among the diabetics taking part: Trevor Huddleston, Bishop of Stepney Tony Mercer of Black and White Minstrel fame, Sue Lloyd, the actress, and Andy Penman, the Scottish International footballer
Interviewer Dr Stephen Black