Letter: Diabetic Polyneuropathy and Cardiovascular Complications in Type 2 Diabetic Patients (Diabetes Metab J 2011;35:390-6)

Corresponding author: Seung-Hyun Ko Division of Endocrinology & Metabolism, Department of Internal Medicine, St. Vincent’s Hospital, The Catholic University of Korea, 93 Ji-dong, Paldal-gu, Suwon 442-723, Korea E-mail: [email protected] Among chronic diabetic complications, diabetic peripheral polyneuropathy (DPN) is characterized by a progressive natural course and severe symptoms. The reported prevalence of DPN varies dramatically depending on differences in diagnostic methods, patient selection, and definition of neuropathy from 8.3% for patients with newly diagnosed type 2 diabetes to up to 50% in patients who have had diabetes for 25 years [1,2]. DPN is often subclinical. Up to 50% of DPN cases may be asymptomatic, and such patients are at risk of insensate injury to their feet. DPN is an important risk factor for foot ulceration, lower limb amputation, and mortality [3,4]. Recently reported observational and epidemiologic studies have shown that the clinical significance of DPN is not confined to the prevention of diabetic foot problems. Relationships have been demonstrated between DPN and other diabetic microvascular complications. Close associations among diabetic nephropathy, retinopathy, and neuropathy have been reported by many studies, both in patients with type 1 and type 2 diabetes mellitus. The EURODIAB Prospective Complication Study showed that diabetic nephropathy and retinopathy were both associated with low nerve conduction velocity and amplitude response in type 1 diabetes [5]. According to a populationbased study of type 2 diabetes performed in Sweden, peripheral sensory neuropathy was related to diabetic retinopathy, overt nephropathy, and peripheral vascular disease [6]. Among diabetic neuropathies, cardiovascular autonomic neuropathy (CAN) is widely accepted as an independent risk factor for future adverse cardiovascular outcomes such as silent myocardial ischemia, cardiac arrhythmia or sudden death [7]. CAN is common in patients with diabetes and is associated with modifiable factors including central fat distribution, hypertension, dyslipidemia, poor diabetes control, and smoking, and with other microvascular complications of diabetes [8]. However, the relationships between DPN and cardiovascular disease (CVD) outcomes in patients with type 2 diabetes have not been fully investigated. Due to a lack of large prospective long-term epidemiologic studies of DPN and cardiovascular or cerebrovascular disease, clinical evidence of their relationships are limited. The EURODIAB Prospective Complications Study included 1,407 patients with type 1 diabetes and showed that cardiovascular risk factors such as male sex, hypertension, obesity, dyslipidemia, and smoking predict the development of large-fiber dysfunction, as measured by vibration perception threshold [9]. Previous clinical history of cardiovascular disease increased the incidence of large-fiber dysfunction with an odds ratio (OR) of 2.13. Coppini et al. [4] showed that higher vibration perception thresholds were more strongly associated with increased mortality than were other microvascular complications in diabetic patients. Letter