Purpose: Hemoglobin (Hb) regulates the endothelial function by modulating the bio-availability of NO at the tissue level. A significant direct relationship is present between the Hb levels and endothelial functions in patients with Type 2 diabetes. Testing whether this association also exists in subjects with prediabetes is important because prediabetes is associated with an increased risk of cardiovascular disease and mortality. Therefore, we investigated the association of Hb both with the classical cardiac risk factors and the markers for endothelial dysfunction and inflammation, in subjects with impaired glucose tolerance (IGT).
Methods: We enrolled 69 normotensive, and cardiovascular events free subjects with IGT (M=40, age=45.50+/-6.8 yr). Plasma insulin, hsCRP, soluble CD40L, vonWillebrand factor, p-selectin levels were measured. The parameters given according to the higher and lower median Hb values of the subjects were compared.
Results: Subjects with the higher Hb levels exhibited lower HDL-C (46.68+/-10.8 mg/dl vs 51.5+/-8.9 mg/dl; P=0.04) and higher systolic (122.57+/-6.2 mmHg vs 116.17+/-7.4 mmHg; p < 0.001) and diastolic (79.14+/-3.73 mmHg vs 75.58+/-6.1 mmHg; P=0.005) blood pressures and sCD40L (7.9+/-3.8 ng/ml vs 6.07+/-2.1 ng/ml; P=0.02) levels. Hb levels were correlated to the HDL cholesterol, sCD40L, systolic and diastolic blood pressures and waist circumference (r=-0.28, P=0.02; r=0.29, P=0.02; r=0.53, P < 0.001; r=0.41, P=0.001; r=0.42, P < 0.001 respectively). According to the multiple logistic regression analysis, Hb was the determinant of sCD40L levels (beta=0.437, P < 0.001).
Conclusion: These results indicate that there may be a link with higher Hb values and cardiovascular risk factors in patients with IGT. Further investigation is warranted to understand the clinical implications of these findings in subjects with prediabetes.