White Blood Cell Count Is Positively Correlated With Albumin Excretion Rate in Subjects With Type 2 Diabetes

White blood cell (WBC) count is one of the main inflammatory markers that predict cardiovascular events (1) and is a component (in nondiabetic subjects) of the insulin resistance syndrome (2), a clustering of cardiovascular risk factors showing insulin resistance as a common denominator (3). It is not known whether WBC count correlates with albumin excretion rate (AER), a component of the insulin resistance syndrome conferring a particularly strong risk of cardiovascular morbidity and mortality (3).

To evaluate whether WBC count correlates with AER in type 2 diabetes, we evaluated 659 Italian type 2 diabetic patients (354 men and 305 women) followed-up at the University Diabetes Unit of the San Luigi Gonzaga Hospital in Orbassano, Turin, Italy, who were not affected by neoplastic, inflammatory, infective, or liver diseases. AER was determined by nephelometric method (Beckman, Milan, Italy). Patient characteristics were (means ± SD) as follows: age 62.00 ± 9.48 years; known diabetes duration 9.59 ± 8.21 years; BMI 29.04 ± 4.94 kg/m²; therapy: diet 38.2%, oral hypoglycemic agents (OHAs) 44.4%, OHAs + insulin 7.2%, insulin alone 10.2%; actual/previous/never smokers: 21/24/55%; and normo-, micro- and macroalbuminuric subjects (i.e., AER <20, 20–200, and >200 μg/min): 72.2, 21.2, and 6.6%. WBC count (mean 7,028.8 ± 1,782.2/μl) was higher in microalbuminuric (7,359 ± 1,882/μl, P = 0.0051) and macroalbuminuric (7,574 ± 1981/μl, P = 0.0143) than in normoalbuminuric subjects (6,882 ± 1,713/μl) and correlated with AER by simple regression (r = .180, P < 0.0001). WBC count was higher in current (7,648 ± 2,108/μl) than in previous (6,929 ± 1,655/μl, P = 0.0012) and in never (6,844 ± 1,656/μl, P < 0.0001) smokers and was similar in men and women. The correlation between WBC count and AER remained significant when subjects were divided according to sex (r = 0.140, P = 0.0072 in men; r = 0.220, P = 0.0001 in women) and smoking status (r = 0.150, P = 0.0004 in never and past smokers; r = 0.230, P = 0.0072 in current smokers) and when only the 544 patients without history of cardiovascular events were considered (r = 0.230, P < 0.0001). WBC count correlated with AER (Std coefficient = 0.102, P = 0.0120) also in a multiple regression model considering age, known diabetes duration, BMI, systolic and diastolic blood pressure, HbA_1c, total and HDL cholesterol, triglycerides, uric acid, creatinine, erythrocyte sedimentation rate, fibrinogen, and hematocrit. When subjects were divided in tertiles according to WBC count (<6,140/μl: i.e., 5,300 ± 645/μl; 6,140–7,500/μl: i.e., 6,778 ± 372/μl; and >7,500/μl: i.e., 9,001 ± 1,424/μl), they differed for BMI (28.6 ± 4.7, 28.8 ± 4.6, and 29.7 ± 5.4 kg/m², ANOVA P = 0.0417), HbA_1c (7.6 ± 1.3, 7.7 ± 1.3, and 8.0 ± 1.5%, ANOVA P = 0.0026), HDL cholesterol (1.33 ± 0.42, 1.31 ± 0.40, and 1.20 ± 0.37 mmol/l, ANOVA P = 0.0016), log triglycerides (0.023 ± 0.003, 0.024 ± 0.002, and 0.025 ± 0.003 mmol/l, ANOVA P < 0.0001), fibrinogen (324.8 ± 79.0, 325.8 ± 69.6, and 363.2 ± 84.6 mg/dl, ANOVA P < 0.0001), hematocrit (40.7 ± 3.2, 41.4 ± 3.8, and 42.0 ± 3.9 mg/dl, ANOVA P = 0.0008), and log AER (1.05 ± 0.56, 1.07 ± 0.57, and 1.28 ± 0.67 μg/min, ANOVA P < 0.0001). For all of the parameters, the first and the second tertiles did not differ, whereas statistical differences were observed between the third and the first and/or the third and the second tertiles (P = 0.01–0.0001). Thus, patients with highest WBC values differed for AER, markers of insulin resistance (BMI, HDL cholesterol, and triglycerides), and inflammation (fibrinogen). In conclusion, in type 2 diabetes, AER correlates with WBC count, one of the major components of the chronic subclinical inflammation associated with both insulin resistance and atherosclerosis (1,2).