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Aims/Introduction: This study aimed to investigate the diagnostic potential of two simplified tests, a point‐of‐care nerve conduction device (DPNCheck™) and a coefficient of variation of R‐R intervals (CVR‐R), as an alternative to traditional nerve conduction studies for the diagnosis of diabetic polyneuropathy (DPN) in patients with diabetes. Materials and Methods: Inpatients with type 1 or type 2 diabetes (n = 167) were enrolled. The study population consisted of 101 men, with a mean age of 60.8 ± 14.8 years. DPN severity was assessed using traditional nerve conduction studies, and differentiated based on Baba's classification (BC). To examine the explanatory potential of variables in DPNCheck™ and CVR‐R regarding the severity of DPN according to BC, a multiple regression analysis was carried out, followed by a receiver operating characteristic analysis. Results: Based on BC, 61 participants (36.5% of the total) were categorized as having DPN severity of stage 2 or more. The multiple regression analysis yielded a predictive formula with high predictive power for DPN diagnosis (estimated severity of DPN in BC = 2.258 – 0.026 × nerve conduction velocity [m/s] – 0.594 × ln[sensory nerve action potential amplitude (μV)] + 0.528In[age(years)] – 0.178 × ln[CVR‐R], r = 0.657). The area under the curve in receiver operating characteristic analysis was 0.880. Using the optimal cutoff value for DPN with severer than stage 2, the predictive formula showed good diagnostic efficacy: sensitivity of 83.6%, specificity of 79.2%, positive predictive value of 51.7% and negative predictive value of 76.1%. Conclusions: These findings suggest that DPN diagnosis using DPNCheck™ and CVR‐R could improve diagnostic efficiency and accessibility for DPN assessment in patients with diabetes. [ABSTRACT FROM AUTHOR]

Although diabetic polyneuropathy (DPN) is the commonest diabetic complication, its pathology remains to be clarified. As previous papers have suggested the neuroprotective effects of glucagon-like peptide-1 in DPN, the current study investigated the physiological indispensability of glucagon gene-derived peptides (GCGDPs) including glucagon-like peptide-1 in the peripheral nervous system (PNS). Neurological functions and neuropathological changes of GCGDP deficient (gcg −/−) mice were examined. The gcg −/− mice showed tactile allodynia and thermal hyperalgesia at 12–18 weeks old, followed by tactile and thermal hypoalgesia at 36 weeks old. Nerve conduction studies revealed a decrease in sensory nerve conduction velocity at 36 weeks old. Pathological findings showed a decrease in intraepidermal nerve fiber densities. Electron microscopy revealed a decrease in circularity and an increase in g -ratio of myelinated fibers and a decrease of unmyelinated fibers in the sural nerves of the gcg −/− mice. Effects of glucagon on neurite outgrowth were examined using an ex vivo culture of dorsal root ganglia. A supraphysiological concentration of glucagon promoted neurite outgrowth. In conclusion, the mice with deficiency of GCGDPs developed peripheral neuropathy with age. Furthermore, glucagon might have neuroprotective effects on the PNS of mice. GCGDPs might be involved in the pathology of DPN. • Deficiency of glucagon gene-derived peptides (GCGDPs) caused peripheral neuropathy with age in mice. • GCGDPs might have neuroprotective effects on the peripheral nervous system of mice. • Glucagon promoted neurite outgrowth of dorsal root ganglion neurons. [ABSTRACT FROM AUTHOR]