INS and type 1 diabetes mellitus: Progression to PDR was only statistically significantly associated with duration of DM (P < 0.005) in the older‐onset group using insulin (WESDR: Klein 1989a and 1994b). Varma 2010 included 324 participants with T1D and T2D; only 17 developed PDR during the four‐year follow‐up.