[Blood viscosity is correlated with insulin resistance]

The insulin resistance syndrome (or syndrome X) is a cluster of symptoms (dyslipidemia, impaired glucose tolerance, overweight, hypertension) associated with a higher risk of atherosclerosis. It has been suggested that hemorheological abnormalities, often found in association with most of these symptoms, may be a part of this syndrome, and possibly play a role in the circulatory abnormalities. In 22 nondiabetic women (20-54 years) presenting a wide range of body mass index (from 20 to 48 kg/m2), insulin sensitivity was assessed with the minimal model procedure, over a 180 min intravenous glucose tolerance test with frequent sampling. The insulin sensitivity index SI (i.e. the slope of the dose-response relationship between insulin increased above baseline and glucose disposal) ranges between 0.1 and 20.1 x 10(-4) min-1/microU/ml) i.e all the range of insulin sensitivity. SI was negatively correlated with blood viscosity (r = -0.530 p < 0.02), body mass index (r = 0.563 p < 0.01) and baseline insulinemia (r = 0.489 p < 0.05). These correlations were independent of each other and were not explained by relationships between SI and fibrinogen or blood lipids. Thus, blood fluidity is correlated with insulin sensitivity when it is measured with an accurate technique, suggesting that blood hyperviscosity is a symptom of insulin resistance that might be involved in the cardiovascular risk of this syndrome.