Chronic Cough and Small Fiber Neuropathy

Inclusion Criteria: In diabetic patients with chronic cough: * Chronic cough defined by cough for more than 8 weeks. * Normal chest X-ray * history of type 2 diabetes * Age of diabetes onset\> 40 years * Affiliated or beneficiary person of social security * Free, informed and written consent In diabetic patients without chronic cough * History of type 2 diabetes * Age of discovery of diabetes\> 40 years * Affiliated or beneficiary person of social security * Free, informed and written consent Exclusion Criteria: * Presence of physical signs of peripheral neuropathy * Active smoking or smoking cessation within the last 12 months * Pregnant or lactating woman * History of non-type 2 diabetes (type I, secondary diabetes, monogenic ...) * Cancer within the last 5 years (except cutaneous squamous cell carcinoma) * History of anti-cancer chemotherapy * Suspicion of autoimmune pathology * Active neurological pathology * Electromyography in favor of large fiber neuropathy * Chronic pathology that may interfere with the neurophysiological assessment * Patient who were given anticoagulation drug therapy, anti-cholinergic drugs, beta-blocker and impossibility to withdraw the treatment before neurophysiological tests In diabetic patients without chronic cough, another non-inclusion criteria is acute or chronic cough