Ever since we started my wife on a phase 2 clinical study for TolerRx we've had a greater appreciation for the challenges diabetes researchers (and private industry) have to make progress in finding a cure. First, it takes a lot of legwork for researchers to FIND people who qualify for the study.
For the candidates, it's simply so hard to make the commitment to undergo a (scary) procedure, do the follow up trials and plan your schedule around the research schedule. Marinda's study required a week long infusion of the test drug... 18 months of follow up... at a research facility hundreds of miles from home. It's a big commitment to make for medical advancement. It's been easier to do as an adult candidate rather than subject our child to it.