Like "You cannot join with it as a preexisitng condition; however, if you are dx’d while serving, there is a medical evaluation process that decides if your duties are hindered to the point that your diabetes makes you “unfit” for duty. My husband was dx’d as type-1 following a deployment to Iraq in 2005. He was retained, while on insulin, for a decade. Eventually, the “needs of the service” caught up with him (they were downsizing, so guess who suddenly became dispensable? Medically vulnerable service members, that’s who."