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

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.