Unveiling the hidden link: diabetes mellitus as a catalyst for orbital apex syndrome

Orbital Apex Syndrome (OAS) is a disease of multiple brain nerves at the orbital apex leading to vision loss and neurological impairments. Diabetes Mellitus (DM), a metabolic disorder with cardiovascular, immunological and neurological effects, is involved in OAS pathogenesis. However, the association between DM and OAS is not well studied. DM and OAS are poorly understood and may not be diagnosed correctly, especially when outbreaks such as COVID-19 are being investigated.

A systematic review of 33 studies published between 2000 and 2025 was conducted to analyze DM-related OAS epidemiology, pathophysiology, clinical phenotypes, and treatment outcomes, focusing on the mechanistic links, pandemic trends, and glycemic control effect on therapeutic effectiveness.

Chronic hyperglycemia induced orbital apex microvascular damage (endothelial dysfunction, thrombosis, vascular senescence), immunosuppression induced opportunistic infections (mostly mucormycosis), and diabetic neuropathy induced neuromuscular dysfunction. During COVID-19, diabetic patients had the highest OAS incidence (more than 70% of cases involved rhino-orbital mucormycosis). Optimal glycemic control is associated with a 32% higher antifungal treatment effectiveness and a 28% lower rate of surgical complications. Epidemiological data showed that DM was the main predisposing factor, with 71.4%-81.8% infectious OAS cases occurred in diabetic populations.

DM is underreported as a critical catalyst for OAS with complications directly increasing severity and progression. Routine DM screening (e.g., glycated hemoglobin monitoring) and integrated glycemic management are essential for OAS prevention and treatment. Long-term studies on inflammatory factors and personalized multidisciplinary care are needed to address mechanistic gaps and improve visual and neurological outcomes in high-risk diabetic patients.