Vocal Shimmer: A Potential Clinical Biomarker for Gestational Diabetes

To investigate the effects of gestational diabetes mellitus (GDM) on vocal characteristics using acoustic, aerodynamic, and subjective assessments.

We evaluated 101 pregnant women between the 24th and 28th gestational weeks. Participants were categorized into Group 1 (GDM Group n = 31) and Group 2 (control group n = 70) groups based on 75-g oral glucose tolerance test results. Objective vocal assessment was performed using Praat software to measure fundamental frequency (f0), jitter, shimmer, harmonics-to-noise ratio (HNR), and cepstral peak prominence-smoothed (CPPS). Aerodynamic efficiency was tested via maximum phonation time and s/z ratio. Subjective vocal well-being was quantified using the Voice Handicap Index-10 (VHI-10).

Prospective cross-sectional study.

No significant differences were found regarding f0, Jitter, or aerodynamic measures (P > 0.05). However, the Group 1 exhibited significantly higher Shimmer (P < 0.001) and significantly lower HNR and CPPS (P < 0.001). Subjectively, Group 1 patients reported significantly higher VHI-10 scores (P = 0.003). Receiver operating characteristic curve analysis identified Shimmer as a moderate discriminative marker (area under the receiver operating characteristic curve = 0.720) for identifying vocal changes associated with GDM, with an optimal cut-off of 3.55% (71% sensitivity, 67.1% specificity). No significant correlation was found between VHI-10 scores and objective parameters (P > 0.05) CONCLUSION: GDM significantly impairs vocal amplitude stability and spectral clarity while preserving f0 and aerodynamic support. The 'subjective-objective mismatch' indicates that the vocal handicap in GDM is multifactorial, potentially reflecting increased vocal effort rather than direct acoustic changes. Shimmer and CPPS emerge as moderate, non-invasive clinical indicators for monitoring the vocal manifestations of the systemic metabolic impacts of GDM on the laryngeal system, offering objective data for multidisciplinary prenatal care.