Metabolic basis of sudden sensorineural hearing loss in diabetes mellitus: From epidemiological association to mechanistic understanding

Table 1 Key epidemiological evidence linking metabolic dysfunction and auditory system disorders

Ref.	Study type	Population	Outcome	Key finding	Grade
Lin et al[13]	Clinical study	Individuals with T2DM	SSNHL risk	OR = 1.59 (T2DM vs non-diabetic); HR = 2.06 (with ≥ 3 glucose-lowering agents); HR = 1.57 (with retinopathy)	Moderate
Horikawa et al[14]	Meta-analysis	Patients with diabetes	SSNHL risk	Overall OR = 2.15	Moderate
Fukui et al[15]	Cohort study	General population	SSNHL risk	Significant association with DM	High
Zhou et al[16]	Clinical analysis	26556 patients with diabetes	SSNHL risk and severity	Risk correlates with DM severity	Low
Costa[17]; Fukushima et al[18]	Clinical studies	SSNHL patients with T2DM	Hearing recovery	Negative prognostic factor for recovery	Low
Zhu et al[23]	Clinical study	General population	SSNHL risk	Progressive increase in risk with HbA1c > 5%	Low

T2DM: Type 2 diabetes mellitus; SSNHL: Sudden sensorineural hearing loss; OR: Odds ratio; HR: Hazards ratio; DM: Diabetes mellitus; HbA1c: Glycated hemoglobin A1c.