Contact phase of blood coagulation in diabetes mellitus.

The first phase of the intrinsic coagulation system was studied in twenty-six diabetic outpatients. The parameters tested were kallicrein, prekallicrein, factor XI and factor XII activities. Kallicrein and factor XI showed significantly elevated activities as compared with a normal control group (P less than 0.05 and less than 0.001, respectively). Factor XI and factor XII levels were higher in non-insulin dependent than in insulin dependent diabetics. We found that the kallicrein-prekallicrein system was activated in our diabetic patients and that such activation could probably be secondary to lesions of the vascular endothelium present in long-term diabetics. No correlation was found between glycaemia and activity levels of this system. Our data represent another demonstration of the existence of a hypercoagulable state in diabetes mellitus.