Blood viscosity at different stages of diabetes pathogenesis.

Hyperglycaemia-induced oxidative stress is implicated as a cause of increased whole blood viscosity (WBV), which is a clinically modifiable risk factor for cardiovascular disease (CVD). However, whether or not there is variation in WBV at different stages of diabetes mellitus (DM) has yet to be confirmed. The sensitivity of underlying oxidative stress has also yet to be investigated. A total of 154 participants representing different stages of DM pathogenesis were selected for the study. Healthy control, prediabetes, DM and DM+CVD groups were compared for variation in WBV levels. The prevalence of oxidative stress, indicated by abnormal levels of erythrocyte glutathione, malondialdehyde and methaemoglobin, associated with high WBV was evaluated. The results showed a statistically significant difference in WBV between groups (P < 0.03). The level of viscosity was significantly lower in the control group relative to the prediabetes group (P < 0.01) and DM+CVD group (P < 0.04). There was no statistically significant difference between the DM+CVD and prediabetes groups. Greater than 76% prevalence of oxidative stress was shown to be associated with high WBV, reaching 95% prevalence in prediabetes. The study showed that WBV varies between individuals with different stages of diabetic macrovascular pathogenesis, including prediabetes. Redefining the criteria for use of WBV on the basis of sensitivity to underlying oxidative stress, rather than specificity to a disease condition, means that this easily performed test is an option to consider in an all-inclusive laboratory approach to early intervention against future diabetic macrovascular complications. This is particularly important for individuals with subclinical hyperglycaemia.