Mary Tyler Moore and Oprah

4 of 13
Offscreen, Mary has served as the international chairman of the Juvenile Diabetes Research Foundation for 23 years. Mary was diagnosed with type 1 diabetes when she was in her 30s—nearly 40 years ago.

Diabetes is a "very deceptive disease," according to Mary. "People say it's not that serious a disease, but it is," she says. "It's pernicious. It just keeps eating away."

Mary herself has felt many effects from the disease but says she's lucky to have good doctors—including her husband. Mary says she's lost a lot of her vision as well as her sense of balance. "That's why I can't ride horses anymore. I don't drive because of the vision," she says. "Arthritis hits at an earlier age. Anything that can go wrong goes wrong in a bigger, earlier way."

In fact, Mary's struggle with diabetes has inspired her to write a new autobiography. "It's the story of how I was happy and had a wonderful life as Mary Tyler Moore, but I never really tested myself," she says. "And it was because of diabetes, I think, that it caused me to grow up. In fact, that's going to be the title of the book—Growing Up Again."