Type 1 diabetes (T1D) can occur at any age a person's pancreas produces little or no insulin. T1D occurs when the body's own defense system (the immune system) attacks and destroys the insulin-producing cells in the pancreas.
Currently Diabetics are not allowed to enlist in the armed forces below is a video about one man who fought it and was allowed to deploy to iraq
http://www.dlife.com/dlifetv/video/sergeant-first-class-mark-thompson
So why cant a Diabetic serve in non combat roles such as the army finance corps or the army medical service corps?