Fibrinogen Glycation and Presence of Glucose Impair Fibrin Polymerization—An In Vitro Study of Isolated Fibrinogen and Plasma from Patients with Diabetes Mellitus

Background: Fibrin formation and structure may be affected by a plethora of factors, including both genetic and posttranslational modifications, such as glycation, nitration or acetylation. Methods: The present study examines the effect of fibrinogen glycation on fibrin polymerization, measured in fibrinogen concentration-standardized plasma of subjects with type 2 diabetes mellitus (T2DM) and in a solution of human fibrinogen exposed to 30 mM glucose for four days. Results: The fibrin polymerization velocity (V(max)) observed in the T2DM plasma (median 0.0056; IQR 0.0049‒0.0061 AU/s) was significantly lower than in non-diabetic plasma (median 0.0063; IQR 0.0058‒0.0071 AU/s) (p < 0.05). Furthermore, significantly lower V(max) was observed for glucose-treated fibrinogen (V(max) 0.046; IQR 0.022‒0.085 AU/s) compared to control protein incubated with a pure vehicle (V(max) 0.053; IQR 0.034‒0.097 AU/s) (p < 0.05). The same tendency was observed in the fibrinogen samples supplemented with 6 mM glucose just before measurements. It is assumed that glucose may affect the ability of fibrinogen to form a stable clot in T2DM subjects, and that this impairment is likely to influence the outcomes of some diagnostic assays. As the example, the impaired clotting ability of glycated fibrinogen may considerably influence the results of the standard Clauss method, routinely used to determine fibrinogen concentration in plasma. The stoichiometric analysis demonstrated that spontaneous glycation at both the sites with high and low glycation potential clearly dominated in T2DM individuals in all fibrinogen chains.