The differential paculiarities of the plasma fibrinolysis and proteolysis indices were studied in patients with diabetic encephalopathy. The inhibition of plasma fibrinolytic potential with deeper changes in case of insulin-independent diabetes mellitus was established. On this background the processes of lysis of low-molecular proteins were inhibited more reliably in case of diabetes mellitus type 2, and were accompanied with the inhibition of degradation of high-molecular proteins and activation of collagenolysis, that indicated the intensity of destabilization of cerebral atherosclerotic plaque.