Association between circulating leukocyte subtype counts and carotid intima-media thickness in Japanese subjects with type 2 diabetes

BACKGROUND An increased leukocyte count is an independent risk factor for cardiovascular events, but the association between leukocyte subtype counts and carotid atherosclerosis in patients with diabetes has not been determined. We therefore investigated the correlation between leukocyte subtype counts and intima-media thickness of the common carotid artery (CCA-IMT) in subjects with type 2 diabetes. METHODS This cross-sectional study involved 484 in-patients with type 2 diabetes (282 males and 202 females), who were hospitalized for glycemic control and underwent carotid ultrasonography at Kumamoto University Hospital between 2005 and 2011. Mean and maximum CCA-IMT was measured by high-resolution B-mode ultrasonography. RESULTS Univariate analyses revealed that mean CCA-IMT was positively correlated with age, systolic blood pressure, brachial-ankle pulse wave velocity (PWV), urinary albumin excretion and duration of diabetes, but was negatively correlated with diastolic blood pressure and fasting plasma glucose. Maximum CCA-IMT was positively and negatively correlated with the same factors as mean CCA-IMT except for fasting plasma glucose. Mean CCA-IMT was positively correlated with total leukocyte (r = 0.124, p = 0.007), monocyte (r = 0.373, p < 0.001), neutrophil (r = 0.139, p = 0.002) and eosinophil (r = 0.107, p = 0.019) counts. Maximum CCA-IMT was positively correlated with total leukocyte (r = 0.154, p < 0.001), monocyte (r = 0.398, p < 0.001), neutrophil (r = 0.152, p < 0.001) and basophil counts (r = 0.102, p = 0.027). Multiple regression analyses showed that monocyte count, age and PWV were significant and independent factors associated with mean CCA-IMT (adjusted R2 = 0.239, p < 0.001), and that monocyte count, age and urinary albumin excretion were significant and independent factors associated with maximum CCA-IMT (adjusted R2 = 0.277, p < 0.001). CONCLUSIONS Monocyte counts were positively correlated with both mean CCA-IMT and maximum CCA-IMT in patients with type 2 diabetes. Monocyte count may be a useful predictor of macrovascular complications in patients with type 2 diabetes. TRIAL REGISTRATION Trial registry no: UMIN000003526.