Elevated whole blood viscosity is associated with an impaired insulin-stimulated myocardial glucose metabolism.

Abstract

Background: Increased whole blood viscosity (WBV) was associated with impaired peripheral glucose metabolism, type 2 diabetes, and cardiovascular disease (CVD). Impaired myocardial glucose metabolism is a risk factor for CVD. Whether an increased WBV is associated with impaired myocardial glucose metabolism is still undefined.

Methods: To elucidate this issue, we evaluated the association between WBV and myocardial glucose metabolic rate (MRGlu) in 57 individuals with different glucose tolerance status. Myocardial MRGlu was assessed using dynamic cardiac ¹⁸F-FDG PET combined with euglycemic hyperinsulinemic clamp. WBV was calculated using a validated equation including hematocrit and plasma proteins: WBV = [0.12 × h] + [0.17 × (p - 2.07)], where h is the hematocrit (%) and p the plasma proteins (g/dl). The subjects were stratified into tertiles according to their myocardial MrGlu values.

Results: As compared with individuals in the highest myocardial MrGlu tertile, those in the lowest tertile showed an age-adjusted increase in WBV (5.54 ± 0.3 cP vs. 6.13 ± 0.4 cP respectively; P = 0.001), hematocrit (39.1 ± 3.1% vs. 43.2 ± 3.7% respectively; P = 0.004), and total proteins (7.06 ± 0.3 g/l vs. 7.60 ± 0.3 g/l respectively; P < 0.0001). WBV was negatively correlated with myocardial MRGlu (r = - 0.416, P = 0.001). In a stepwise multivariate regression analysis, including several cardiovascular risk factors, the only variables significantly associated with myocardial MrGlu were WBV (β - 0.505; P < 0.0001), fasting insulin (β - 0.346; P = 0.004), fasting plasma glucose (β - 0.287; P = 0.01), and sex (β 0.280; P = 0.003) explaining the 69.6% of its variation.

Conclusions: The current study showed a strongly association between an increase of WBV and an impaired myocardial glucose metabolism in individuals with a broad spectrum of glucose tolerance.