Diabetes-linked otolith dysfunction appears biologically dissociable on vestibular testing
Adults with diabetes can carry vestibular impairment that does not behave like a single uniform disorder. In this cohort of 166 adults aged 28 to 80 years, vestibular evoked myogenic potentials and graviception measures pulled apart in ways that matter clinically: absent ocular VEMPs were frequent, cervical VEMPs were uncommon, and neither pattern mapped neatly onto subjective visual vertical during dynamic otolith stimulation.
The signal was not just in the ear. It also reached the muscle system.
After retinoscopy, electromyography, audiology, vestibular testing and quadriceps strength evaluation, 43.9% of participants had absent ocular VEMPs, while 5.4% had absent cervical VEMPs. Those two responses, though both rooted in otolith physiology, did not rise and fall together. Ocular VEMPs were unrelated to on-axis or off-axis subjective visual vertical estimates, yet they tracked quadriceps strength, a finding that places peripheral sensorimotor compromise and metabolic burden in the same clinical frame.
Otolith reflex loss did not mirror graviception during motion
The study design separated static perception from motion-evoked perception, which gives the results real bedside weight. Investigators measured Subjective Visual Vertical under static conditions and during on-axis and off-axis rotation to probe utricular and semicircular canal stimulation. Even with that more demanding physiologic challenge, S.V.V. during rotation showed no linear relation to present or absent VEMPs. Instead, the dynamic graviception measure related to the standard deviation of static S.V.V., a marker of precision, and to an interaction among gender, high blood pressure and dyslipidemia.
This pattern argues against a simple one-to-one map between vestibular reflex loss and perceptual distortion of gravity. It also suggests that diabetic vestibular injury may be filtered through broader vascular and metabolic factors before it becomes visible as a symptom or as a psychophysical abnormality. A patient can therefore have an abnormal otolith reflex without a parallel defect in graviception testing, or the reverse.
Quadriceps strength may be a clinically relevant marker of systemic compromise
The association between absent ocular VEMPs and quadriceps strength deserves attention because it shifts the conversation from isolated vestibular testing to whole-body diabetic complications. Quadriceps weakness can reflect disuse, neuropathy, sarcopenia, microvascular disease, or a combination of those processes. In that setting, an absent ocular VEMP may be less a standalone vestibular curiosity than a marker of more diffuse neuromuscular compromise.
This is the kind of result that changes how clinicians think about a vestibular workup in diabetes. When vestibular pathways and lower-limb strength deteriorate together, the practical consequence is a greater risk of imbalance, slower postural correction, and reduced reserve during daily ambulation. A person may not volunteer classic vertigo, yet still carry enough sensorimotor impairment to struggle with stability in dim light, on uneven ground, or during head turns.
Macrovascular risk factors may shape the diabetic vestibular phenotype
The interaction between gender, high blood pressure and dyslipidemia in relation to dynamic S.V.V. points toward a macrovascular contribution. In diabetes, the inner ear and its afferent pathways sit inside a vascular system that is vulnerable to endothelial dysfunction, small-vessel injury and impaired perfusion. Otolith structures are metabolically active and highly dependent on intact blood flow, so vascular compromise can plausibly degrade reflex performance without creating a perfectly symmetric pattern across every vestibular assay.
Static S.V.V. precision also emerged as relevant. Lower precision implies more variable perception of verticality, even when gross directional bias is not obvious. In practice, variability can be just as disruptive as overt misalignment, because postural control depends on stable sensory estimates from moment to moment. A person whose perception of vertical swings from trial to trial may be more vulnerable to falls than one with a consistent, compensable offset.
Ocular and cervical VEMPs behaved as separate clinical signals
The separation between ocular and cervical VEMPs is one of the most important findings in the report. Ocular VEMPs and cervical VEMPs are often discussed under the umbrella of otolith testing, but the present data show that their absence can be dissociated in adults with diabetes. Only a small fraction lacked cervical VEMPs, while nearly half lacked ocular VEMPs, a gap too wide to dismiss as chance alone.
From a pathophysiologic standpoint, this separation suggests different vulnerabilities along the utricular and saccular pathways, or different thresholds for dysfunction across afferent channels and central relays. Diabetes does not need to damage all vestibular elements equally. Microvascular injury, axonal dysfunction, glycative stress and metabolic inefficiency may strike certain pathways earlier or more visibly than others, especially when systemic vascular risk factors are layered on top.
What the cohort does and does not establish
The study is cross-sectional, so it cannot determine sequence, progression, or causality. It does show that in adults with diabetes, otolith dysfunction can be present without a uniform collapse in graviception, and that peripheral vestibular findings can diverge from one another rather than converging into a single abnormal phenotype. The cohort also demonstrates that metabolic compromise and macrovascular factors may contribute to this disorder, but the exact biological route remains unmeasured here.
No funds, grants or other support were received, and the investigators declared no competing interests. Those disclosures do not change the clinical message. They do, however, leave the dataset anchored in a single-center style physiologic question rather than a broad interventional framework.
For clinicians, the practical implication is straightforward: diabetes-related dizziness or imbalance should not be dismissed when standard bedside impressions seem mild. Absent ocular VEMPs, especially when paired with reduced quadriceps strength or vascular risk factors, may flag a more complex sensorimotor burden than symptoms alone reveal. The unresolved issue is whether routine vestibular testing in diabetes can identify patients early enough to alter fall risk or guide targeted rehabilitation before compensation fails.