Brief report Increased red cell count in diabetes and pre-diabetes D. Simmons a,b, * a Institute of Metabolic Science, Cambridge University Hospitals NHS Foundation Trust, Cambridge, England, UK b Dept. of Rural Health, University of Melbourne, Shepparton, Australia 1. Introduction An increased haematocrit and blood viscosity are important determinants of blood rheology and are also associated with an increased risk of coronary heart disease [1,2]. Diabetic patients have been shown to respond normally to haematocrit variation, suggesting that a raised haematocrit would also be associated with an increased risk of macrovascular disease [3]. Haematocrit is dependent on the number and nature of erythrocytes and the question as to whether erythrocytes are ‘‘normal’’ in diabetes has arisen. Decreased erythrocyte deformability [4] and a 10% increase in red cell count (RCC) (‘‘relative polycythaemia’’) have previously been shown [5]. Erythrocyte deformation is inversely related to HbA1c [6] and red cell number is positively correlated with the HbA1 [5]. More recently, RCC has been shown to be associated with insulin resistance [7]. We wondered if other pre-diabetic states also had an increased RCC. 2. Materials and methods The ‘‘Crossroads study’’ was carried out between June 2001 and March 2003 across seven Australian towns as previously described [8–10]. Briefly, an initial census of 2376 randomly selected households (half in the regional centre, a twelfth in each of the six smaller towns) was undertaken. All usual (at least 6 months) residents aged 25 years who participated in the census were invited to attend a morning ‘‘clinic’’ fasting. Demographic, health, socioeconomic, anthropometric and blood pressure data were collected [8–10]. Glucose was collected and measured as previously described [8]. Diabetes, diabetes research and clinical practice 90 (2010) e 50– e 53 article info Article history: Received 5 April 2010 Received in revised form 7 July 2010 Accepted 13 July 2010 Published on line 10 August 2010 Keywords: Diabetes HbA1c Red cell count Haemoglobin Gestational diabetes abstract The aim of this study was to test whether an increased red cell count (RCC) is present in pre- diabetes, obesity and the metabolic syndrome. The results demonstrate that these diabetes precursor states are associated with an increased RCC. This relationship can be explained, in part, by an increased HbA1c. # 2010 Elsevier Ireland Ltd. All rights reserved. * Correspondence address: Institute of Metabolic Science, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 2QQ, UK. Tel.: +44 1223 216 913; fax: +44 1223 217 080. E-mail address: dsworkster@gmail.com. Contents lists available at ScienceDirect Diabetes Research and Clinical Practice journal homepage: www.elsevier.com/locate/diabres 0168-8227/$ – see front matter # 2010 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.diabres.2010.07.005