Smell dysfunction and related factors in diabetic patients

To analyze smell function in diabetic patients and healthy control subjects, with reference to individual characteristics and major complications of the disease.

A cross-sectional study of smell recognition in 68 diabetic patients and 30 control subjects without known cause of smell impairment was conducted. Smell was studied using a kit of flavors that patients were asked to recognize, leading to a smell recognition score ranging from 0 (no recognition) to 20 (perfect recognition). Demographic and clinical data, and the electrogustometric threshold were recorded in both groups. Metabolic control and degenerative complications were studied in diabetic patients.

The SRS was significantly lower in diabetic patients than in control subjects (12.4 +/- 0.5 vs. 15.1 +/- 0.5, P < 0.001). By use of univariate and multivariate analyses, this difference could not be explained by individual factors such as age, sex, body mass index, blood pressure, or tobacco or alcohol consumption but was related to diabetes. SRS correlated with EGT (r = 0.70, P < 0.001). In the diabetic group, SRS was associated with age (r = 0.29, P < 0.05), duration of diabetes (r = 0.27, P < 0.05), microalbuminuria (12.2 +/- 0.8 vs. 14.4 +/- 0.9, P < 0.05), peripheral neuropathy (10.3 +/- 1.0 vs. 14.1 +/- 0.9, P < 0.01), and EGT (r = 0.39; P < 0.001). By use of multivariate analysis, the strongest association was found with EGT (R2 = 0.15).

These results suggest that smell recognition is impaired in patients with diabetes mellitus. Smell dysfunction is associated with age and degenerative complications of diabetes, suggesting a degenerative mechanism related to diabetes.