Cerebral arterial pulsatility and insulin resistance in type 2 diabetic patients

Diabetic patients have a threefold risk for cerebrovascular disease compared with nondiabetic controls. The aim of the present study was to investigate the association of insulin resistance with the pulsatility index (PI) of cerebral arteries in type 2 diabetic patients. We compared a group of 90 patients with stroke-free, type 2 diabetes and an age- and sex-matched control group of 45 healthy subjects without diabetes. We then evaluated the PI of the middle cerebral artery (MCA) by transcranial Doppler ultrasonography (TCD), and insulin resistance was determined by a short insulin tolerance test. The PI was significantly higher in diabetic patients than in healthy controls (p<0.05) and also higher in patients with insulin resistance than that seen in insulin sensitive diabetic patients (p<0.05). The PI of the MCA was significantly correlated with age (R=0.465, p<0.01), duration of diabetes (R=0.264, p=0.025) and hypertension (R=0.285, p=0.015) and inversely correlated with the insulin resistance index (Kitt: R=-0.359, p=0.030). A multiple regression analysis was performed with PI as the dependent variable and insulin resistance as an independent variable along with known clinical risk factors. Age (beta=0.393, p<0.01) and duration of diabetes (beta=0.274, p=0.043) exhibited a significant independent contribution to PI. PI could be a useful marker in the detection of diabetic cerebrovascular changes, and insulin resistance showed correlations with PI, but age and the duration of diabetes contributed independently to the variability in the PI.