Efficacy and safety of local vs. systemic steroid therapy for patients with sudden deafness and diabetes mellitus: A systematic review and meta‑analysis

The present study aimed to systematically evaluate the effects of local steroid injection (LSI) vs. systemic steroid therapy (SST) on glycemic control, clinical efficacy and safety in diabetic patients with sudden sensorineural hearing loss (SSNHL), and to compare different LSI routes [postauricular steroid injection (PSI) vs. intratympanic steroid injection (ITSI)] as well as combination LSI strategies. PubMed, Embase, Cochrane Library, Web of Science, Google Scholar, China National Knowledge Infrastructure and Wanfang Data databases were systematically searched from inception to February 2026. Studies comparing LSI (PSI or ITSI) with SST in diabetic patients with SSNHL were included. Two investigators independently screened the literature, extracted data and assessed methodological quality. Meta‑analysis was conducted using RevMan 5.4 and Stata 14.0. A total of 18 studies involving 1,577 patients were included. The overall methodological quality of the included studies was moderate to high. Compared with SST, LSI was associated with markedly lower fasting blood glucose (FBG) levels [mean difference (MD), ‑1.09 mmol/l], lower 2‑h postprandial blood glucose (PBG) levels (MD, ‑2.05 mmol/l) and a reduced incidence of hyperglycemic events [risk ratio (RR), 0.18]. In addition, LSI achieved a markedly higher overall response rate (ORR) (RR, 1.14) and greater hearing threshold improvement [MD, 3.14 dB hearing level (HL)]. No significant difference was observed in the overall incidence of adverse events (AEs) between local and systemic therapy (RR, 0.49). However, subgroup analysis showed that PSI was associated with fewer AEs than SST (RR, 0.37), whereas no significant difference was observed between ITSI and SST. PSI and ITSI demonstrated comparable ORRs (RR, 1.00) and hearing threshold improvements (MD, 0.73 dB HL), although PSI was associated with fewer AEs (RR, 0.39) and slightly higher FBG levels (MD, 0.48 mmol/l). Furthermore, combination LSI achieved a higher ORR (RR, 1.25) and better hearing recovery than single‑route LSI. Sensitivity analysis confirmed the robustness of the pooled results, and no substantial publication bias was detected. In conclusion, in diabetic patients with SSNHL, LSI provides better glycemic control and superior therapeutic efficacy compared with SST, while maintaining a comparable overall safety profile. PSI and ITSI demonstrate similar efficacy, although PSI appears to be associated with fewer AEs. Combination LSI may further improve clinical outcomes; however, additional high‑quality studies are needed to confirm its benefits.