# Case–Controlled Clinical Assessment of the Olfactory System via Cranial Magnetic Resonance Imaging in Patients With Type 2 Diabetes Mellitus

## TL;DR

This study uses MRI to find that type 2 diabetes patients show structural changes in their olfactory system compared to healthy individuals.

## Contribution

The study reveals a link between long-term type 2 diabetes and structural olfactory system changes using cranial MRI.

## Key findings

- T2DM patients showed significant differences in olfactory bulb volume, tract length, and sulcus depth compared to controls.
- Longer diabetes duration and higher HbA1c levels correlated with structural olfactory system disorders (p < 0.01).

## Abstract

The purpose of this study is to assess the olfactory system of patients with T2DM using the cranial magnetic resonance imaging (MRI) method.

This is a retrospective case–control study in which a group of T2DM patients and a control group were compared. The results of the examinations of the olfactory systems of the patients by cranial MRI were transferred to a data collection form. Descriptive statistical methods, chi‐squared tests, the Mann–Whitney U test, and Spearman's correlation coefficient were used to analyze the data.

It was determined that 66.7% of the case group were women, the mean age of the patients in the group was 52.50 ± 7.41, and their mean T2DM diagnosis duration was 6.48 ± 3.18 years. There were statistically significant differences between the case and control groups in terms of their olfactory bulb volume (OBV), olfactory tract length (OTL), and olfactory sulcus depth (OS) values. Longer T2DM durations and elevated HbA1c levels were significantly associated with structural disorders of the olfactory system (p < 0.01).

A longer duration of T2DM and elevated HbA1c levels trigger the structural disorders of the olfactory system. In comparison to healthy controls, we identified prominent changes in the olfactory bulb volumes, olfactory tract lengths, and olfactory sulcus depths of T2DM patients. This reveals the need for T2DM patients to pay more attention to their diet and insulin treatment. Similarly, olfactory dysfunction in T2DM patients should be carefully monitored by clinicians.