The present findings suggest that TyG-Index is better associated with carotid atherosclerosis than HOMA-IR.

The GLP-1 receptor agonist exenatide has been approved for adjunctive treatment of type 2 diabetes. Continuous GLP-1 infusion improves endothelial function in vivo; no evidence about a beneficial effect of exenatide on vascular function has been published. The aim of our observational study was to evaluate whether exenatide would improve brachial artery function evaluated by the flow mediated dilation (FMD) technique, compared with glimepiride, in subjects with type 2 diabetes. FMD time course was assessed by ultrasound, after 5 min forearm ischaemia, at baseline and after 16-week treatment. At the end of the study FMD was significantly higher in subjects who assumed exenatide compared with glimepiride (9.1 ± 3.6 vs. 5.6 ± 1.0, p = 0.01). Even if limited by the small number of studied subjects, who were not matched in the two treatment groups, this research study represents the first FMD evidence suggesting that chronic administration of exenatide improves arterial dilation.

OBJECTIVEBlood viscosity (BV) is higher in diabetic patients and might represent a risk factor for the development of insulin resistance and type 2 diabetes. However, data in subjects with normal glucose or prediabetes are missing. In the current study, we evaluated the relationship between BV and blood glucose in subjects with normal glucose or prediabetes. RESEARCH DESIGN AND METHODSEnrolled subjects were divided into three groups according to blood glucose: group A (n = 74), blood glucose <90 mg/dL; group B (n = 96), blood glucose ranging from 90 to 99 mg/dL; and group C (n = 94), blood glucose ranging from 100 to 125 mg/dL. BV was measured at 378C with a cone-plate viscometer at shear rates ranging from 225 to 22.5 s 21 . RESULTSBlood pressure, blood lipids, fibrinogen, and plasma viscosity were similar in the three groups. BMI and waist circumference were significantly increased in group C. Hematocrit (P < 0.05) and BV (P between 0.01 and 0.001) were significantly higher in groups B and C compared with group A. Blood glucose was significantly and inversely correlated with HDL cholesterol and directly with BMI, waist, hematocrit (r = 0.134), and BV (from 225 s 21 to 22.5 s 21 ; r ranging from 0.162 to 0.131). BV at shear rate 225 s 21 was independently associated with blood glucose. CONCLUSIONSThe current study shows a direct relationship between BV and blood glucose in nondiabetic subjects. It also suggests that, even within glucose values considered completely normal, individuals with higher blood glucose levels have increased BV comparable with that observed in subjects with prediabetes.

Hemodynamic forces play a role in the development of atherosclerosis. Their variations with age have been assessed in cross-sectional, but not longitudinal, studies. The aim of the present study was to investigate in both sexes the age-dependent change in wall shear stress and arterial stiffness in subjects studied twice 12 years apart. Forty-eight subjects (15 women and 33 men) were studied twice 12 years apart. Subjects underwent blood viscosity measurement and echo-Doppler of carotid arteries, from which the intima-media thickness (IMT) was measured and the wall shear stress and Peterson's elastic modulus were calculated. Blood viscosity increased in both sexes, more markedly in women (+13.2%) than men (+7.2%). Common carotid diameter increased in both sexes, but in men (+7.4%) more than in women (+5.5%). Peak and mean velocity decreased at follow-up by 10.7% and 18.9% in women and by 14.2% and 18.1% in men. Peak and mean shear stress significantly decreased in men by 13.0% and 17.5%, respectively, while in women only the mean shear stress was reduced (−11.8%). The IMT of the common carotid artery increased by 29% in women and 20% in men. Arterial stiffness significantly increased (+74.5% in women and +28.0% in men). The percent change in mean shear stress was significantly and inversely associated with the percent change in IMT. The data of this study show that, in a middle-aged population observed for almost 12 years, the mean shear stress decreases significantly in both sexes, while peak shear stress decreases significantly only in men. The change in mean shear stress is inversely associated with changes in IMT. Arterial stiffness, on the other hand, increases with aging.

BACKGROUND AND AIM: The relationship between hyperlipidemia and blood and plasma viscosity is not completely clear. While increasing viscosity is often reported with increasing blood lipids, lipid-lowering treatments are often unable to normalize the viscosity values. Aim of this study is to try to clarify the relationship between blood lipids and viscosity. METHODS AND RESULTS: Apparently healthy subjects were enrolled (n = 410). Smokers, diabetics, obese, and hypertriglyceridemic (above 400 mg/dl) were excluded. Blood (at shear rate 225/s) and plasma viscosity were measured at 37 • C. Erythrocyte rigidity (Tk) was calculated according to Dintenfass. Blood lipids and glucose were measured by routine methods. Hyperlipidemic subjects (n = 315) had higher values of plasma viscosity (1.44 ± 0.13 vs. 1.40 ± 0.12 cP, p = 0.007), and blood viscosity (4.51 ± 0.54 vs. 4.35 ± 0.55 cP, p = 0.013), compared to normolipidemic subjects (n = 95). In simple correlation analysis, plasma viscosity was directly associated with LDL cholesterol, and inversely with Tk and HDL cholesterol. In multiple regression analysis the association with LDL and HDL was strengthened, though these two variables as a whole accounted for only 5% (adjusted R 2 ) of the variability of plasma viscosity. Blood viscosity was significantly associated with haematocrit, plasma viscosity, Tk and all considered variables but age in simple correlation analysis, but only with haematocrit, plasma viscosity and Tk in multiple regression analysis. CONCLUSIONS: LDL cholesterol and HDL cholesterol influence plasma viscosity, but not blood viscosity. Triglycerides up to values of 400 mg/dl do not seem to have important effects, at least in apparently healthy subjects and at the shear rates used in the present study. The contribution of LDL and HDL cholesterol to plasma viscosity seems however quite limited.