Letter to the Editor Regarding: Diabetic Peripheral Neuropathy as a Predictor of Asymptomatic Myocardial Ischemia in Type 2 Diabetes Mellitus: A Cross-Sectional Study

Diabetes mellitus (DM) frequently affects the nervous system [1]. This holds true both for the peripheral and for the autonomic nervous system [2]. Diabetic polyneuropathy (or distal symmetrical polyneuropathy [DPN] or, simply, peripheral neuropathy) is the most common manifestation of DM in the nervous system [3, 4]. Of the autonomic nervous system, gastrointestinal autonomic neuropathy [5] and cardiovascular autonomic diabetic neuropathy (CAN) are those most widely studied. Importantly, CAN is a recognised harbinger of cardiovascular mortality [6–8]. What is known about the impact of diabetic polyneuropathy (DPN) on mortality? First, DPN is shown to be independently associated with mortality in a number of studies [9–11]. Second, neuropathic diabetic foot ulcers have also been associated with a 5-year mortality rate that approaches the amazing 50% [12–14], exceeding the rate of several cancer types, including breast, prostate, colon, and Hodgin's disease [14]. In addition, Charcot osteoarthropathy may also be associated with increased mortality [15], more recently attributable to coronary artery disease [16–18]. In this issue of the journal, Baltzis et al. [19] have investigated the relationship between DPN and myocardial ischaemia (MI) in patients with type 2 diabetes mellitus (T2DM) and no history of cardiovascular events. Overall, 82 patients with DPN (n = 41) or without DPN (n = 41) were included. Among those with DPN, 15 had active ulcers. MI was estimated through Technetium-99 m Sestamibi Single-Photon Emission Computed Tomographic imaging expressed as Summed Stress Score (SSS): SSS C4 was considered abnormal. Furthermore, two well-known indices of CAN (abnormal RR ratio and orthostatic hypotension) were used to detect this condition [1, 2, 8]. DPN was diagnosed clinically by the established examination system Neuropathy Disability Score (NDS) and defined as NDS C5 [1, 2]. A negative 10-g monofilament test served to exclude DPN [1, 2]. In this study [19], patients with DPN had a higher risk of abnormal SSS than those without DPN (46.3% vs. 9.8%, p\0.001). Multivariate