Blood pressure directly correlates with blood viscosity in diabetes type 1 children but not in normals

Abstract

Objective: To determine the relationship between mean arterial blood pressure (MAP) and blood viscosity in diabetic type 1 children and healthy controls to investigate whether MAP is independent of blood viscosity in healthy children, and vice versa.Research design and methods: Children with diabetes type 1 treated by insulin injection were studied. Controls were healthy children of both sexes. MAP was calculated from systolic and diastolic pressure measurements. Blood viscosity was determined indirectly by measuring blood hemoglobin (Hb) content. The relationship between Hb, hematocrit (Hct) and blood viscosity was determined in a subgroup of controls and diabetics selected at random.Results: 21 (10.6 ± 2.5 years) type 1 diabetic children treated with insulin and 25 healthy controls age 9.6 ± 1.7 years were studied. Hb was 13.8 ± 0.8 g/dl in normal children vs. 14.3 ± 0.9 g/dl in the diabetic group (p < 0.05). MAP was 71.4 ± 8.2 in the normal vs. 82.9 ± 7.2 mmHg in the diabetic group (p < 0.001). Glucose was 89.3 ± 10.6 vs. 202.4 ± 87.4 mg/dl respectively. Diabetics had a positive MAP/Hb correlation (p = 0.007), while normals showed a non significant (p = 0.2) negative correlation. The blood viscosity/Hb relationship was studied in a subgroup of 8 healthy controls and 8 diabetic type 1 children. There was no significant difference in Hb and Hct between groups. Diabetics showed a trend of increasing blood viscosity (+7%, p = 0.15).Conclusions: Normal children compensate for the increase in vascular resistance due to increased blood viscosity (increased Hb and Hct) while diabetic children do not, probably due to endothelial dysfunction.

Blood pressure and blood viscosity are not correlated in normal healthy subjects

“…In a study of 128 normotensive members of a large employed population in New York City (51 ± 10 years) there was a significant independent relation between MAP and blood viscosity,9 and a study of 628 individuals in the population of Victoria de Durango with men and women pooled data showed a weak positive correlation between MAP and Hct 10. Our findings and some11,12 but not all results in the literature13,14 support the contention that Hct and blood viscosity are not a factor in regulating blood pressure in the healthy normal population within limits that include the systematic elevation of Hct due to adaptation to moderate altitude.…”

“…The results of this study, those from experimental studies16 and results in children12 and premenopausal women11 indicate that blood pressure is not correlated with blood viscosity. Therefore a population presenting a positive correlation between blood pressure and blood viscosity (or Hct) is probably affected by endothelial dysfunction and/or pathologies that reduce or abolish the endothelial response to shear stress 17.…”

Coagulatory Defects in Type-1 and Type-2 Diabetes

“…Again, the origin of this difference is not known but could be due to differences in methodology or to different stages of progression of the disease in the individuals studied. Changes in plasma protein concentrations as well as plasma glucose levels lead to an increase in plasma viscosity in T2DM [44] and an increasing trend has been measured in T1DM, especially in individuals with bad glycaemic control [45,46]. Most but not all changes in the protein concentration of coagulatory proteins in plasma are due to uncontrolled glycaemia and so can often be reversed through control of blood glucose levels: for example, protein C, protein S and antithrombin concentrations have been demonstrated to increase in T2DM subjects following improvement in glycaemic control [47].…”

Cross-sectional and longitudinal association between hemoglobin concentration and hypertension

“…[ 8 , 9 ] However, other studies reported that blood pressure is not correlated with blood viscosity in healthy individuals. [ 10 – 12 ]…”