This is copied verbatim from an answer I gave on yahooanswers in response to the question, Can I live to be 80 if I have type 1 diabetes.
Insulin has only been available for injection since 1922 (that's 91 years). So far, about sixty people are known to have lived 75 or more years on insulin (I don't know what age you developed diabetes or were diagnosed, so I don't know how long you need to live with diabetes in order to live to age 80, but your odds are best if either you were diagnosed before puberty, or else the older the better).
The vast majority of people with type 1 diabetes, even since insulin has been around, have died young. However, it's not hard to find exceptions.
For instance, Barbara Wagler was diagnosed at the age of 12, in 1936, and she received a Joslin 75 year medal at the age of 88.
Robert Bates, who received the 75 year medal at the age of 80 (he was diagnosed at the age of 5) passed away this year at the age of 86.
Spencer Wallace was diagnosed at the age of 8 and is now alive at the age of 90.
Dorothy Jane Williams of Sarasota, Florida was diagnosed at the age of 11 and is now 87 years old.
Frank Newby of Johnson City, Tennessee was diagnosed at the age of 2, and is now 81 years old.
Patricia Youell was diagnosed at the age of 7 years old, and is 85 or 86.
Barbara Kimbrough was diagnosed at the age of 9 years old, and died earlier this year at the age of 90.
Jack Little of Australia was diagnosed at the age of 15 and he made it to at least 85:
Kathryn Ham was diagnosed at the age of 8 and is now 84.
Bob Dornhecker of Dallas was diagnosed at 11, and is now 86 years old.
Edward Danielson was diagnosed at the age of 10, and died last year at the age of 91.
Sheila Thorn, who was diagnosed as a baby, died at the age of 81: http://www.diabetes.org.uk/About_us/News_Landing_Page/Sheila-Thorn-whose-story-moved-many-dies-aged-81/
John Hegan, who is 81 now, was diagnosed at the age of 3.
Gerald and Robert Cleveland, who are brothers, were diagnosed at the ages of 16 and 3, and were both alive at ages 92 and 88- not sure if they still are.