Asymptomatic electronystagmographic abnormalities in patients with type I diabetes mellitus

Only a few studies have investigated vestibular function in diabetes mellitus (DM), showing contradictory results. We have performed an electronystagmographic (ENG) evaluation of 46 individuals with type I DM and 37 healthy controls. No patient reported subjective vestibular symptoms. Duration of caloric-induced nystagmus (DN) was significantly lower (2.1 +/- 0.7 vs. 2.6 +/- 0.4 min, p less than 0.01), and central nystagmus frequency of caloric response also nonsignificantly tended to be decreased (37.4 +/- 16.5 vs. 41.7 +/- 12.7 beats/30s, p = 0.21) in DM patients, as compared to controls. The latter comparison achieved significance after exclusion of newly diagnosed diabetic patients (33.4 +/- 16.1 vs. 41.6 +/- 12.7 beats/s, p less than 0.05). Depressed caloric reactions were seen in 21.8% of patients. DN was lower in patients with microalbuminuria and retinopathy, but this was not observed after exclusion of newly diagnosed diabetic patients, all of whom had normal ENG responses and no chronic diabetic complications. The existence of a lower DN and central nystagmus frequency should be borne in mind when interpreting ENG tracings in patients with long duration type I diabetes mellitus.