This question has been posted twice before by Lorenzo the Magnificent but hasn't been definitively answered here and my Google search was unrevealing. Who is the fastest type 1 diabetic marathoner? Alex Collins ran a 2:48 in 2014 at the London Marathon and that is best time I could find so far. I know there are competitive cyclists and at least one competitive triathlete that are type 1 diabetics as well, but couldn't find much about runners. Couldn't find much for female type 1 diabetics either. Just curious.
Also it appears that at least two patients with end stage renal disease on dialysis have run a marathon. Pretty impressive.