How young can you detect Type 1 Diabetes in an infant?

Diabetes runs in my husbands side of the family, and he was diagnosed at 11 withtype 1 diabetes. We have a 6 month old baby girl and im just curious as to how early type 1 diabetes can be detected or how early it can occur. I Would appriciate any info on the type of tests that are run to diagnose this in an infant or young child.Thanks!