I am the father of a Type 1 who is 8 years old. The problem is the same with any of the diabetes tools: you have to manually enter the numbers. Until you can get around this fundamental problem, you will have difficulty getting people to use the app. A mobile app helps, but it really needs to be automated. Also, many people will not share sensitive health information with a random website.

Keep an eye on what Google Health and Microsoft's Health Vault are doing. Good luck.