@article {1240, title = {Differential white blood cell count and type 2 diabetes: systematic review and meta-analysis of cross-sectional and prospective studies.}, journal = {PLoS One}, volume = {5}, year = {2010}, month = {2010 Oct 18}, pages = {e13405}, abstract = {

OBJECTIVE: Biological evidence suggests that inflammation might induce type 2 diabetes (T2D), and epidemiological studies have shown an association between higher white blood cell count (WBC) and T2D. However, the association has not been systematically investigated.

RESEARCH DESIGN AND METHODS: Studies were identified through computer-based and manual searches. Previously unreported studies were sought through correspondence. 20 studies were identified (8,647 T2D cases and 85,040 non-cases). Estimates of the association of WBC with T2D were combined using random effects meta-analysis; sources of heterogeneity as well as presence of publication bias were explored.

RESULTS: The combined relative risk (RR) comparing the top to bottom tertile of the WBC count was 1.61 (95\% CI: 1.45; 1.79, p = 1.5*10(-18)). Substantial heterogeneity was present (I(2) = 83\%). For granulocytes the RR was 1.38 (95\% CI: 1.17; 1.64, p = 1.5*10(-4)), for lymphocytes 1.26 (95\% CI: 1.02; 1.56, p = 0.029), and for monocytes 0.93 (95\% CI: 0.68; 1.28, p = 0.67) comparing top to bottom tertile. In cross-sectional studies, RR was 1.74 (95\% CI: 1.49; 2.02, p = 7.7*10(-13)), while in cohort studies it was 1.48 (95\% CI: 1.22; 1.79, p = 7.7*10(-5)). We assessed the impact of confounding in EPIC-Norfolk study and found that the age and sex adjusted HR of 2.19 (95\% CI: 1.74; 2.75) was attenuated to 1.82 (95\% CI: 1.45; 2.29) after further accounting for smoking, T2D family history, physical activity, education, BMI and waist circumference.

CONCLUSIONS: A raised WBC is associated with higher risk of T2D. The presence of publication bias and failure to control for all potential confounders in all studies means the observed association is likely an overestimate.

}, keywords = {Adult, Aged, Cross-Sectional Studies, Diabetes Mellitus, Type 2, Female, Humans, Leukocyte Count, Male, Middle Aged, Prospective Studies}, issn = {1932-6203}, doi = {10.1371/journal.pone.0013405}, author = {Gkrania-Klotsas, Effrossyni and Ye, Zheng and Cooper, Andrew J and Sharp, Stephen J and Luben, Robert and Biggs, Mary L and Chen, Liang-Kung and Gokulakrishnan, Kuppan and Hanefeld, Markolf and Ingelsson, Erik and Lai, Wen-An and Lin, Shih-Yi and Lind, Lars and Lohsoonthorn, Vitool and Mohan, Viswanathan and Muscari, Antonio and Nilsson, Goran and Ohrvik, John and Chao Qiang, Jiang and Jenny, Nancy Swords and Tamakoshi, Koji and Temelkova-Kurktschiev, Theodora and Wang, Ya-Yu and Yajnik, Chittaranjan Sakerlal and Zoli, Marco and Khaw, Kay-Tee and Forouhi, Nita G and Wareham, Nicholas J and Langenberg, Claudia} }