Diagnosed with the incurable, insulin-dependent disease at the young age of 12, Garber admits it took him most of his teenage and early twenties "to acknowledge that it was serious."
"We knew very little about it and it was difficult to accept," Garber, 66, tells PEOPLE in this week's magazine.
The Legends of Tomorrow star adds, "Now, I think it's important to talk about the disease, especially to children who are traumatized and think their lives are over."
In effort to start the discussion, Garber has joined forces with Beyond Type 1, a platform for those diagnosed with type 1 diabetes to share their stories.
For more from Garber and his fight against diabetes, pick up this week's issue of PEOPLE, on newsstands Friday
"Beyond Type 1 is really addressing young kids directly," Garber explains. "The website gives them a place to ask question and to see how other people are dealing with it and how parents are dealing with it."
RELATED VIDEO: Diabetes Alert Dog Becomes Girl's Best Friend
Because of his personal experience with the disease, Garber knows that there is life beyond the diagnosis.
"I think the worst feeling for any kid is to think that their life has been cut short or diminished in some way by this disease," he says. "What we need is a cure, but in the meantime we're here to say, you can live with it and thrive. Type 1 diabetes does not define who you are."