Highlights
- •Limited research exists about reversing olfactory dysfunction in type 2 diabetics.
- •Three interventions were identified in the scoping review.
- •Hyperbaric oxygen and GLP-1 agonists showed improvement in smell identification.
- •DPP-4 inhibitors did not produce meaningful improvement in smell identification.
- •Other therapeutics such as olfactory training should be investigated in diabetics.
Abstract
Introduction
Olfactory dysfunction (OD) is highly prevalent amongst type 2 diabetes mellitus (DM2)
patients and has many associated health risks. For example, OD can lead to poor nutrition,
safety issues related to diminished hazard detection, and increased mortality rates.
While limited research exists about therapeutics for DM2-associated OD, recovery of
olfactory function is better studied in other pathologic states. The objectives of
this scoping review are to synthesize the existing data on interventions for DM2-associated
OD and present the evidence for therapies that have been utilized for non-DM2-associated
causes of OD. Additionally, the potential therapeutic opportunities for patients with
DM2 are explored.
Methods
A scoping review was conducted with a medical librarian to identify studies investigating
treatments of DM2-related OD. 6 databases were searched (Embase, CINAHL, the Cochrane
Library, Google Scholar, OVID Medline, and Web of Science). Studies were eligible
if the primary discussion involved treatment of olfactory deficits in the context
of DM2. All publication dates were included, and studies published in languages other
than English were excluded.
Results
3631 articles were identified; 3 articles met inclusion criteria and underwent full
text review. Hyperbaric oxygen (HBO), the DPP-4 inhibitor Linagliptin and the GLP-1
agonists Exenatide and Liraglutide are the only therapeutics that have been used in
the context of DM2. Only HBO and GLP-1 agonists produced statistically significant
improvements in olfactory identification. The literature regarding non-DM2-associated
OD supports interventions such as olfactory training, dietary supplements, and intranasal
insulin. Specifically, olfactory training was very effective in many contexts such
as post-viral and traumatic OD while being affordable and non-invasive.
Conclusion
This scoping review of olfactory rehabilitation options for DM2-induced OD demonstrates
a paucity of prospective investigations of plausible therapeutics. Additionally, treatments
for OD related to non-DM2-associated etiologies, such as olfactory training, are well-studied,
efficacious, and should be investigated in the context of DM2. Future investigation
has the potential to enhance the quality of clinical intervention for OD and improve
short- and long-term outcomes for DM2 patients.
Keywords
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Article info
Publication history
Published online: May 31, 2022
Accepted:
May 21,
2022
Received in revised form:
April 21,
2022
Received:
December 14,
2021
Identification
Copyright
© 2022 Primary Care Diabetes Europe. Published by Elsevier Ltd. All rights reserved.
