Research paper The relationship of plasma viscosity with microvascular complications in the diabetic elderly and its predictive value S. Aras a, *, M. Varli a , I. Tek b , O.K. Cengiz a , A. Yalcin a , T. Atli a a Department of Geriatric Medicine, Ankara University School of Medicine, Cebeci, Ankara 06110, Turkey b Medicana International Ankara, Department of Medical Oncology, Sogutozu, Ankara 06110, Turkey 1. Introduction Diabetes mellitus (DM) is a common metabolic disorder affecting elderly people. In addition to the acute complications, morbidity and mortality due to chronic complications are also frequent in DM. Chronic complications are classified as macro- vascular complications including coronary artery disease, periph- eral artery disease and microvascular complications such as neuropathy, retinopathy and nephropathy [1]. Several different mechanisms are responsible for the develop- ment of chronic complications and include activation of the polyol pathway, formation of glycated proteins and advanced glycation end products (AGE), abnormalities in lipid metabolism, increased oxidative damage, hyperinsulinemia, hyperperfusion of certain tissues, endothelial dysfunction and activation of various growth factors. Hemorheological changes expressing the flow properties of the blood is also one of them [1]. Hemorheology investigates the flow properties of the blood and deformation characteristics of the cellular elements in the blood. It is argued that the alterations in the hemorheological system play a role in the pathogenesis of many diseases including chronic complications of DM [2,3]. It has been proven in studies that out of the hemorheological parameters, plasma viscosity (PV) is an independent risk factor in many pathologies, such as atheroscle- rosis, coronary artery disease and peripheral artery disease, in addition to inflammatory diseases [4,5]. PV changes depend on serum protein changes; particularly decrease of albumin and increase of globulin [6,7]. According to many studies conducted, there is an elevation in the PV at the very early stages of diabetes in diabetic patients and this elevation contributes greatly to the development of chronic complications of diabetes [8]. In previous years, PV was used quite widely in the diagnosis and follow-up of infection and inflammation diseases. PV has high sensitivity and specificity in inflammatory rheumatic diseases, particularly in rheumatoid arthritis and temporal arteritis [9]. However, it has been less and less used in practice in recent years. Besides being an acute phase reactant like CRP, there are some studies arguing that it has an etiological role in more chronic pathologies [4,5,9–11]. European Geriatric Medicine 3 (2012) 271–276 A R T I C L E I N F O Article history: Received 13 March 2012 Accepted 18 May 2012 Available online 21 June 2012 Keywords: Diabetes mellitus Old age Diabetic microvascular complications Plasma viscosity A B S T R A C T Purpose: The aim of our study is to define the association between microvascular complications and plasma viscosity (PV) in the diabetic elderly and to determine whether PV measurement can be used as a potential marker for microvascular complications of diabetes. Methods: In this cross-sectional study consisted of people aged 65 or over, 226 of them had diabetes and 59 of them did not. Those with inflammatory disease, infection and organ failure were not included in the study as they could affect PV. Diabetic cases are categorized into groups according to their microvascular complications. The PV of all the cases was measured by Brookfield DV-II viscometer. Results: PV is significantly higher in diabetic patients when compared to the non-diabetic control group (1.71  0.17 mPa s and 1.48  0.06 mPa s respectively, P < 0.001). PV is higher in DM patients with neuropathy as compared to those without any microvascular complications (1.76  0.16 mPa s and 1.60  0.07 mPa s respectively, P < 0.001). In all the dual and triple combinations of microvascular complications, the average PV is found to be significantly higher than those with no complications (for all groups P < 0.001). In addition, there is statistically significant positive association between the severity of diabetic retinopathy and PV (P < 0.001). Conclusion: PV is clearly elevated in the diabetic elderly, particularly in patients with microvascular complications. These elevations are significantly correlated with the duration of diabetes, metabolic control level and the number of microvascular complications. Studies are needed to show the cause and effect relationship between diabetic complications and PV in the elderly. ß 2012 Elsevier Masson SAS and European Union Geriatric Medicine Society. All rights reserved. * Corresponding author. 446, Sokak Dog ˘ukent Caddesi, Vadi ikizleri sitesi 3B/7, Birlik, Ankara, Turkey. E-mail address: sevgidursun06@yahoo.com (S. Aras). Available online at www.sciencedirect.com 1878-7649/$ – see front matter ß 2012 Elsevier Masson SAS and European Union Geriatric Medicine Society. All rights reserved. http://dx.doi.org/10.1016/j.eurger.2012.05.003