title: Presence of neuropathic pain may explain poor performances on olfactory testing in diabetes mellitus patients.
abstract: Olfactory dysfunction in neurodegenerative conditions such as Parkinson's syndrome and Alzheimer's disease can hallmark disease onset. We hypothesized that patients with diabetes mellitus, a condition featuring peripheral and central neurodegeneration, would have decreased olfaction abilities. We examined participants with diabetic peripheral neuropathy, participants with diabetes without diabetic peripheral neuropathy, and control participants in blinded fashion using standardized Sniffin' Sticks. Diabetic peripheral neuropathy severity was quantified using the Utah Early Neuropathy Scale. Further subcategorization of diabetic peripheral neuropathy based on presence of neuropathic pain was performed with Douleur Neuropathique 4 Questionnaires. Participants with diabetes had decreased olfactory sensitivity, impaired olfactory discrimination abilities, and reduced odor identification skills when compared with controls. However, loss of olfaction ability was, at least partially, attributed to presence of neuropathic pain on subcategory assessment, although pain severity was not associated with dysfunction. Those participants with diabetes without diabetic peripheral neuropathy and those with diabetic peripheral neuropathy without neuropathic pain had similar olfactory function as controls in general. The presence of neuropathic pain, associated with limited attention and concentration, may explain at least a portion of the olfactory dysfunction witnessed in the diabetic patient population.
authors.affiliation: Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.
authors.forename: Shauna
authors.initials: S
authors.lastname: Brady
authors.forename: Paul
authors.initials: P
authors.lastname: Lalli
authors.forename: Nisha
authors.initials: N
authors.lastname: Midha
authors.forename: Ayechen
authors.initials: A
authors.lastname: Chan
authors.forename: Alexandra
authors.initials: A
authors.lastname: Garven
authors.forename: Cynthia
authors.initials: C
authors.lastname: Chan
authors.forename: Cory
authors.initials: C
authors.lastname: Toth
mesh_terms: D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000503:physiopathology*; D003929:Diabetic Neuropathies / Q000150:complications* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009437:Neuralgia / Q000150:complications* / Q000503:physiopathology*; D012044:Regression Analysis; D012903:Smell
keywords: diabetic neuropathic pain; diabetic neuropathy; olfaction; type 2 diabetes mellitus