New aspects of the insulin resistance syndrome: impact on haematological parameters

Aim/Hypothesis. Previous studies have shown that insulin has an important i n vitro role in the regulation of human erythropoiesis. We investigated whe ther in vivo hyperinsulinaemia/insulin resistance affects haematological pa rameters. Methods. A total of 608 subjects between 22 and 99 years of age were enroll ed in the Chianti study, an epidemiological study of factors affecting mobi lity in old age. The degree of insulin resistance was assessed using the ho meostasis model. Results. We found a correlation between insulin resistance and red blood ce ll count, (r = 0.14 p < 0.001), plasma haemoglobin (r = 0.16 p < 0.001), ha eatocrit (r = 0.15 p < 0.001) and plasma iron (r = 0.1 p < 0.05) concentrat ions. Red blood cell count was also associated with the other biological ma rkers of insulin resistance syndrome. Subjects with higher insulin resistan ce (4 degrees quartile) had higher red blood cell count, plasma triglycerid es and low density lipoproteins (LDL) cholesterol concentrations and lower high density lipoproteins (HDL) cholesterol concentrations then subjects at the lowest quartiles of insulin resistance. Insulin resistance and BMI wer e significant and independent predictors of red blood cell count even when the analysis was adjusted for age, sex, waist-to-hip ratio, plasma iron and drug intake. Conclusion/hypothesis. Our findings provide in vivo evidence of a relation between hyperinsulinaemia/insulin resistance, the main variables of insulin resistance syndrome and erythropoiesis. Increased red blood cell count cou ld be considered as a new aspect of the insulin resistance syndrome that co uld contribute to the increased risk of developing cardiovascular problems.