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Chronic Inflammatory Demyelinating Polyneuropathy Chronic Inflammatory Demyelinating Polyneuropathy in Diabetes Patients Alon Abraham, MD, 1 Majed Alabdali, MD, 1,2 Mohammad Qrimli, MD, 1 Ari Breiner, MD, 1 Carolina Barnett, MD, 1 Hans D Katzberg, MD, 1 Bruce A Perkins, MD 3 and Vera Bril, MD 1 1. Ellen and Martin Prosserman Centre for Neuromuscular Diseases, Division of Neurology, Department of Medicine, University Health Network, University of Toronto, Toronto, Canada; 2. Department of Neurology, King Fahad University Hospital, University of Dammam, Saudi Arabia; 3. Division of Endocrinology and Metabolism, Department of Medicine, Mount Sinai, Hospital and Lunenfeld Tanenbaum Research Institute, University of Toronto, Toronto, Canada Abstract Diabetes mellitus (DM) is pandemic, and is the leading global cause of polyneuropathy, most commonly, a distal symmetric sensorimotor polyneuropathy (DSP). By contrast, chronic inflammatory demyelinating polyneuropathy (CIDP) is rare, and characterized mainly by symmetrical proximal and distal muscles weakness. There are currently 15 sets of criteria using a variable combination of clinical, electrophysiologic, laboratory, and biopsy features to identify CIDP, but it is unclear if these criteria are the same in patients with and without DM. Slowed conduction velocity, a feature of demyelination, is observed in patients with type 1 DM with poor control, and the clinical characteristics of these patients differ from those who have CIDP and DM, suggesting a different pathophysiology. Treatment response rates in CIDP patients, with and without DM, are as high as 80 %, and it is recommended that treatment be started early to prevent secondary axonal loss. However, patients with type 1 DM with CIDP are far less likely to be treated than CIDP patients who do not have DM. In patients with type 1 DM with polyneuropathy who have prominent weakness or demyelination in electrophysiologic studies, a diagnosis of CIDP and a trial of therapy should be considered. Keywords CIDP, diabetic neuropathy, distal symmetric polyneuropathy, CSF, nerve biopsy Disclosures: Alon Abraham, MD, Majed Alabdali, MD, Mohammad Qrimli, MD, Ari Breiner, MD, and Carolina Barnett, MD, have no conflicts of interest to declare. Hans D Katzberg, MD, has received research grants and speaker support from Grifols; research grants, advisory board honoraria, and speaker support from CSL Behring; and speaker/travel support from Genzyme Canada. Bruce A Perkins, MD, serves as an advisor to Neurometrix Inc. Vera Bril, MD, has been a consultant for Bionevia, CSL, Dainnipon Sumitomo, Eisai, Grifols, Lilly, and Pfizer, and has received research support from all the companies listed in her disclosure. No funding was received in the publication of this article. Open Access: This article is published under the Creative Commons Attribution Noncommercial License, which permits any noncommercial use, distribution, adaptation, and reproduction provided the original author(s) and source are given appropriate credit. Received: February 4, 2015 Accepted: February 18, 2015 Citation: US Neurology, 2015;11(1):47–52 Correspondence: Vera Bril, MD, Toronto General Hospital 200 Elizabeth Street, Room 5 EB 309, Toronto, Ontario, Canada M5G 2C4. E: vera.bril@utoronto.ca Diabetes mellitus (DM) is a leading cause of peripheral neuropathy. 1–3 A distal symmetric sensorimotor polyneuropathy (DSP), is the most common manifestation, 4 and is considered to be mainly due to axonal degeneration and progressive loss of nerve fibers. 5–7 However, focal and multifocal peripheral nerve lesions, comprising cranial, thoracoabdominal, and limb nerve lesions, including proximal lumbosacral radiculoplexus neuropathies, can also occur. 8 In contrast to the common DSP phenotype, chronic inflammatory demyelinating polyneuropathy (CIDP) is characterized by motor greater than sensory, proximal, and distal peripheral neuropathy, with a slowly progressive or relapsing course. 9 It is also associated with impaired sensation, absent or diminished tendon reflexes, and elevated cerebrospinal fluid (CSF) protein level, as well as demyelinating features observed on nerve conduction studies. 10 However, different variants exist, including a primary sensory ataxic form. 11,12 Therapy should be initiated early in the course of the disease to prevent ongoing demyelination and secondary axonal loss leading to permanent disability. 10 Although there are similar treatment response rates between patients with diabetes Tou ch MEd ica l MEdia (CIDP+DM) and without diabetes (CIDP-DM), 13–16 CIDP+DM patients are less likely to receive immune therapies. 13,15 This is possibly due to the greater challenge of diagnosing CIDP in DM patients who likely also have DSP. The difficulty in the diagnosis might be attributable to CIDP clinical heterogeneity, multifocality, predilection for proximal nerve segments, and the limitations of electrophysiologic and pathologic investigations in distinguishing between primary demyelinating and axonal processes. 17 Although there are abundant research criteria for the diagnosis CIDP, 18 and these may be appropriate in the research setting, such rigorous electrophysiologic criteria lack sensitivity for the diagnosis, and may miss clinical cases of CIDP. 9 Currently, there are no widely accepted practical clinical criteria on which to base treatment. 17 Epidemiology DM is pandemic, with a prevalence of 8.3 % as per the International Diabetes Federation’s Diabetes Atlas 2012; however, it is estimated that up to half of all cases have not been diagnosed. 19 In those greater than 47