Advanced Glycation End Products and Antioxidant Status in Type 2 Diabetic Patients With and Without Peripheral Artery Disease ANNUNZIATA LAPOLLA, MD 1 FRANCESCO PIARULLI, MD 1 GIOVANNI SARTORE, MD 1 ANTONIO CERIELLO, MD 2 EUGENIO RAGAZZI, MD 3 RACHELE REITANO, MD 1 LORENZO BACCARIN, MLT 1 BARBARA LAVERDA, MD 1 DOMENICO FEDELE, MD 1 OBJECTIVE — Advanced glycation end products (AGEs), pentosidine and malondialdehyde (MDA), are elevated in type 2 diabetic subjects with coronary and carotid angiopathy. We investigated the relationship of AGEs, MDA, total reactive antioxidant potentials (TRAPs), and vitamin E in type 2 diabetic patients with and without peripheral artery disease (PAD). RESEARCH DESIGN AND METHODS — AGEs, pentosidine, MDA, TRAP, vitamin E, and ankle-brachial index (ABI) were measured in 99 consecutive type 2 diabetic subjects and 20 control subjects. RESULTS — AGEs, pentosidine, and MDA were higher and vitamin E and TRAP were lower in patients with PAD (ABI 0.9) than in patients without PAD (ABI 0.9) (P  0.001). After multiple regression analysis, a correlation between AGEs and pentosidine, as independent vari- ables, and ABI, as the dependent variable, was found in both patients with and without PAD (r = 0.9198, P  0.001 and r = 0.5764, P  0.001, respectively) but not in control subjects. When individual regression coefficients were evaluated, only that due to pentosidine was confirmed as significant. For patients with PAD, considering TRAP, vitamin E, and MDA as independent variables and ABI as the dependent variable produced an overall significant regression (r = 0.6913, P  0.001). The regression coefficients for TRAP and vitamin E were not significant, indicating that the model is best explained by a single linear regression between MDA and ABI. These findings were also confirmed by principal component analysis. CONCLUSIONS — Results show that pentosidine and MDA are strongly associated with PAD in type 2 diabetic patients. Diabetes Care 30:670 – 676, 2007 D iabetes is associated with a greatly increased risk of cardiovascular dis- ease, which cannot be explained by known risk factors, such as smoking, hy- pertension, and dyslipidemia (1). Recent studies indicate that hypergly- cemia is an important contributor to the development of these complications. In this framework, among the biochemical alterations characteristic of hyperglyce- mia, factors involved in determining ath- erosclerotic disease are formation of advanced glycation end products (AGEs), increased polyol pathway flux, increased hexosamine pathway flux, and protein ki- nase C activation (2–5). All of these mo- lecular mechanisms reflect a single hyperglycemia-induced process of over- production of superoxide by the mito- chondrial electron transport chain. Thus, hyperglycemia and increased oxidative stress (6) lead to tissue damage through common pathways. In particular, AGEs may cause damage through the formation of abnormal cross-links in collagen, thus contributing to vascular stiffening (2–5); modification of lipoprotein, as a result of glycation, may contribute to foam cell formation (2–5). In diabetes, reduced an- tioxidant defenses have also been de- scribed, thus providing an additional contribution to the development of chronic complications (7). Recent studies reported that the se- rum level of AGEs is increased in type 2 diabetic patients with coronary heart disease (8 –10). Immunohistochemical studies have also shown that AGEs ac- cumulate in coronary atherosclerotic plaques and cardiac tissue of diabetic patients (11). Among AGEs in patients with type 2 diabetes, high serum pento- sidine (a marker of glycoxidation- induced cross-linking) is associated with both increased carotid intima- media wall thickness and arterial stiff- ening (12). Malondialdehyde (MDA) is frequently measured as an indicator of lipid peroxidation and oxidative stress in vivo and is elevated in diabetic pa- tients with macroangiopathy (13). Pe- ripheral artery disease (PAD) is a strong predictor of coronary and carotid ath- erosclerosis (14 –16) and affects about 29% of patients with type 2 diabetes (17). To our knowledge, no data are avail- able about the involvement of AGEs and oxidative stress in PAD in diabetic pa- tients. The aim of our study was to detect a value of the ankle-brachial index (ABI) of 0.9, indicating the presence of PAD, in a group of type 2 diabetic patients and to compare those with positive results with those with negative results with re- spect to glycolipid oxidation products ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● From the 1 Department of Medical and Surgical Sciences, University of Padova, Padova, Italy; 2 Warwick Medical School, Coventry, U.K.; and the 3 Department of Pharmacology and Anesthesiology, University of Padova, Padova, Italy. Address correspondence and reprint requests to Francesco Piarulli, MD, Medical and Surgical Sciences, University of Padova, Via dei Colli 4, 35143 Padova, Italy. E-mail: francesco.piarulli@unipd.it. Received for publication 18 July 2006 and accepted in revised form 28 November 2006. Abbreviations: ABI, ankle-brachial index; AGE, advanced glycation end product; FPG, fasting plasma glucose; LC, liquid chromatography; MDA, malondialdehyde; PAD, peripheral artery disease; PCA, principal component analysis; R-PE, R-phycoerythrin; TRAP, total reactive antioxidant potential. A table elsewhere in this issue shows conventional and Syste `me International (SI) units and conversion factors for many substances. DOI: 10.2337/dc06-1508 © 2007 by the American Diabetes Association. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Pathophysiology/Complications O R I G I N A L A R T I C L E 670 DIABETES CARE, VOLUME 30, NUMBER 3, MARCH 2007