Insulin resistance syndrome and fibrinolytic activity: The Northern Sweden MONICA Study

Background. Many studies have, in small and highly selected study populations, described how cardiovascular risk factors tend to cluster in subjects with insulin resistance. Recently, interest has focused on possible relationships between this insulin resistance syndrome and fibrinolysis, and the role of triglycerides in this association. The present study addresses these issues in a general population. Methods. A subsample of participants in the population-based Northern Sweden MONICA (MONItoring of trends and determinants in CArdiovascular diseases) Study, consisting of 353 men and 403 women in the 25-64 year age range, was investigated. Insulin resistance was estimated indirectly from the fasting levels of insulin and glucose. Fibrinolytic activity was measured both as plasminogen activator inhibitor type 1 (PAI-1) activity and tissue plasminogen activator (tPA) activity. Results. Insulin resistance was highly correlated with those cardiovascular risk factors that have been associated with the insulin resistance syndrome, and to the measures of fibrinolytic activity. Subjects in the upper tertile of insulin resistance had a PAI-1 activity that was three times higher than that of the lower third in men and twice as high in women. There was a strong interaction between insulin resistance and serum triglycerides. Low versus high levels of both variables together were associated with a fivefold difference in PAI-I activity in men and a threefold difference in women. The tPA activity was inversely correlated to both insulin resistance and serum triglycerides. Conclusions. In a general population, the 'insulin resistance syndrome' is closely associated with low fibrinolytic activity. Serum triglyceride levels interact with insulin resistance to predict fibrinolytic activity.