in my case the stress was a dose of flu that laid me out flat for about 4 days, appeared on Thursday but as I was going home Friday I worked through it.
Speaking to the consultant at my annual review just before Christmas, his view was that there is an underlying susceptibility/genetic predisposition and the external stressor may be enough to tip the scales from reduced/declining pancreatic function to a point where it becomes clinically diagnosable as T1D.
I realise the stress of a dose of flu is not comparable to the military experiences, but it's that extra stress that just triggers the autoimmune response.