INTRODUCTION: Type 1 diabetes (T1D), one of the most common childhood diseases worldwide, can cause hearing loss through systemic effects. Diabetes-induced hearing loss is considered a progressive sensorineural hearing loss with a gradual onset, typically occurring at high frequencies (HFs). Extended HF (EHF) hearing sensitivity in children with T1D who did not complain of hearing loss was investigated as an early marker for hearing loss at the standard/conventional frequency range of hearing.
METHODS: Forty-two children (21 with T1D and 21 healthy controls) were evaluated in a case-control design. Conventional and EHF (14,000, 16,000, and 18,000 Hz) audiometry were performed. The diabetes group underwent routine blood biochemistry and glycated hemoglobin A1c measurements. The data were analyzed by the Students t-test, Mann-Whitney U test, chi-square test, and logistic regression analysis.
RESULTS: The mean hearing thresholds were significantly higher (p<0.05) in the diabetes group than in controls at 500, 2,000, 4,000, and 8,000 Hz [all <15 decibel hearing level (dB HL)]. The number of ears with thresholds >15 dB HL at 14,000-18,000 Hz but ≤15 dB HL at 500-4,000 Hz was significantly higher in the diabetes group than in the control group (p=0.049).
DISCUSSION AND CONCLUSION: Children with diabetes showed normal hearing thresholds within the conventional audiometric frequency range but they had higher hearing thresholds during EHF audiometry when compared with controls. Audiometry in these children should be performed using frequencies above 8,000 Hz combined with the conventional frequency range. EHF audiometry may be an effective method for identifying subclinical hearing loss in children with diabetes. Thus, diabetic children with an EHF mean hearing threshold above 15 dB HL should be monitored more closely in terms of blood glucose regulation to prevent diabetes-related hearing loss at the conventional frequency range.