Association of Insulin Resistance and Hematologic Parameters: Study of a Middle-aged and Elderly Chinese Population in Taiwan

Abstract

Chronic inflammation is a common feature related to changes in hematologic parameters in insulin resistance. The aims of this study were to explore the relationship between hematologic parameters and insulin resistance, and to establish a gerontologic profile for following studies. Residents aged over 40 years in 3 major townships in I-Lan County participating in the Adult Health Examination were invited for the study. Diagnosis of diabetes mellitus (DM) was done according to American Diabetes Association criteria. Insulin resistance was measured by homeostasis model assessment (HOMA-IR), and subjects with the highest tertile of HOMA-IR were defined as being insulin resistant. Hematologic parameters including white blood cell (WBC) count, red blood cell (RBC) count, hemoglobin, and platelet count were measured for comparisons. A total of 857 subjects (mean age, 64.6 +/- 11.2 years; male/female, 373/484) participated in this study. Their mean body mass index (BMI) was 24.5 +/- 3.7 kg/m2, and 42.4% of them were obese and 21.8% were overweight. The overall prevalence of DM was 15.4% (7.7% were previously diagnosed and 7.7% were newly diagnosed), and impaired fasting glucose was 7.2%. Trend analyses confirmed that age, BMI, HOMA-IR, WBC and platelet counts were significantly increased as glycemic metabolism exacerbated (p = 0.007, < 0.001, < 0.001, < 0.001 and 0.025, respectively). Compared with insulin-sensitive subjects, insulin-resistant subjects were more likely to be females (70.2% vs. 49.7%, p < 0.001), and had significantly higher BMI (26.2 +/- 3.9 kg/m2 vs. 23.7 +/- 3.3 kg/m2, p < 0.001), HOMA-IR (3.6 +/- 3.5 vs. 0.7 +/- 0.3, p < 0.001), WBC count (6686.9 +/- 1889.2/mm3 vs. 5942.9 +/- 1740.4/mm3, p < 0.001), and platelet count (243.5 +/- 70.9 x 10(3)/mm3 vs. 231.0 +/- 62.2 x 10(3)/mm3, p = 0.011), but not age (64.5 +/- 11.0 years vs. 64.6 +/- 11.4 years, p = 0.93) or RBC count (4.6 +/- 0.6 M/mm3 vs. 4.6 +/- 0.6 M/mm3, p = 0.76). When age and sex were controlled, HOMA-IR significantly correlated with WBC count (gamma = 0.23, p < 0.001) and platelet count (gamma = 0.09, p = 0.007). However, by multiple logistic regression, female gender, overweight and obesity, and elevated WBC count were all found to be independent risk factors of insulin resistance, but age, RBC and platelet counts were not. Elevated WBC count but not RBC count was significantly associated with insulin resistance and glycemic metabolism. The relationship between platelet count and insulin resistance deserves further investigations.