Relationships between fibrinogen and insulin resistance.

A relationship between plasma fibrinogen levels and insulinemia, as well as the different parameters of the insulin resistance syndrome has been described. The aim of the present paper was to investigate whether plasma fibrinogen concentrations were linked to plasma insulin levels or to the degree of insulin resistance. For this purpose, 62 nondiabetic, nonhypertensive patients, 30 men and 32 women, with body mass indexes (BMIs) and ages ranging from 18.6 to 50.2 kg/m(2) and from 19 to 60 years, respectively, were studied. Insulin sensitivity was quantified by the minimal model procedure over a 180-min intravenous glucose tolerance test with iterative sampling. Plasma insulin was determined by radioimmunoassay without cross-reactivity to human proinsulin, and fibrinogen by the method of Clauss. Insulin sensitivity ranged from 0.009 to 23.2 min(-1)/(microU/ml)x10(-4), covering the whole range of insulin sensitivities. Fibrinogen ranged from 1.70 to 5.07 g/l. There was a significant negative correlation between fibrinogen and insulin sensitivity (r=-0.76,P<0.0001) and a positive correlation between fibrinogen and basal insulin (r=0.56,P<0.0001). After adjustment for BMI, body fat mass and waist-to-hip ratio, these two relationships remained significant. In addition, a multiple regression analysis was performed to assess the independent effect of the following related variables: fibrinogen, insulin sensitivity, insulinemia and BMI. Only insulin sensitivity appeared to account for the ability to predict fibrinogen values. Thus, we hypothesized it was likely that the state of insulin resistance rather than hyperinsulinemia per se was related to hyperfibrinogenemia. We proposed an interpretation of these data in connection with some factors like free fatty acids or tumor necrosis factor-alpha, which have been implicated in the pathogenesis of insulin resistance. Nevertheless, prospective and intervention studies are needed to assess whether there is a simple association or a causal relationship between insulin resistance and hyperfibrinogenemia.