This study enrolled type 2 diabetic patients with PDR who had to undergo vitrectomy during the period May 2011-January 2012 at the Unit of Ophthalmology, A.O. Civil Hospital and University of Brescia. Inclusion criteria were the following: type 2 diabetes, age greater than 18 years, and PDR; exclusion criteria were: age less than 18 years, type 1 diabetes, initial DR, PDR patients not requiring surgery, previous vitrectomy in the eye under examination or other ophthalmic surgery or laser therapy within the previous 3 months.