Background
Auditory functions among patients with type 2 diabetes mellitus (DM) are controversial regarding
cochlear or neural changes and the relationship between these changes and serum level of
glycosylated hemoglobin (HbA
1c
%).
Aim of the study
The aim of the study was to investigate auditory dysfunctions in type 2 DM patients with poor
versus good glycemic control.
Materials and methods
The present study was conducted on three groups: two diabetic groups with poor and good
glycemic control (n = 18 and 14, respectively) based on serum HbA
1c
% and one healthy control
group (n = 30) matched with age, sex, and BMI. All participants were subjected to clinical
assessment, audiometry, brainstem auditory evoked potential ( BAEP), and evoked acoustic
emissions transient evoked otoacoustic emissions and distortion product otoacoustic emissions
(TEOAEs and DPOAEs).
Results
Diabetic patients with poor glycemic control had significantly elevated hearing thresholds compared
with other groups at low and high frequencies in audiometry (P < 0.01 and P < 0.001). They showed
significantly prolonged absolute latency in wave I and interpeak latency ( III–V) in the BAEP test
compared with other groups (P < 0.001). DM patients with poor glycemic control had significantly
low amplitudes at all frequencies in the TEOAE test, as well as at high frequencies (4 and 6 kHz)
on the DPOAE test, compared with other groups (P < 0.001 and P < 0.05, respectively). There
were significant correlations between HbA
1c
% and interpeak latency III–V (r = 0.340, P = 0.004)
on the one hand and overall response of TEOAE amplitude (r = −0.471; P = 0.000) on the other.
Conclusion
Diabetic patients with poor glycemic control had worse auditory dysfunctions on both cochlear
and neural findings.