To assess the prevalence of mucormycosis related fungal sinusitis in uncontrolled diabetic patients in tertiary care hospitals in Karachi and its association with glycemic control, clinical severity and important risk factors. Participants were 385 adult patients (HbA₁c ≥ 8%) with suspected fungal sinusitis presenting at three tertiary care sites between August 2023 to July 2024. Participants underwent chart review to obtain data on demographic and diabetes-related parameters, as well as clinical presentation, endocrine/histological/pathological/radiographic findings, and environmental/behavioral exposures. Prevalence was calculated overall and within HbA₁c sub-groups. Mean HbA₁c and clinical extent of disease were assessed using one way ANOVA, while χ² tests assessed for differences in prevalence across glycemic groups. Of the 385 patients, 46 (11.9%) had confirmed rhinocerebral mucormycosis. Prevalence increased from 7.5% in the HbA₁c < 8% group to 15.2% for those with HbA₁c > 10%, (χ² = 6.24, p = .044). Overall, sinus only disease was the most common, impacting 60.9% of all patients, while orbital involvement and cerebral involvement occurred in 30.4% and 8.7% of patients, respectively. Mean HbA₁c increased significantly with disease severity, (sinus only 9.1 ± 1.2%; orbital 10.5 ± 1.5%; cerebral 11.3 ± 1.8%; F = 8.72, p < .001). Major risk factors included diabetic ketoacidosis (76.1%), use of broad-spectrum antibiotics (54.3%), use of corticosteroids (43.5%), exposure to construction sites (32.6%), and exposure to soil (21.7%). In Karachi, nearly one in eight uncontrolled diabetic patients will develop rhinocerebral mucormycosis, and patients with mucormycosis have identifiable risk factors related to glycemic control and exposure to the environment. Therefore, implementation of rigorous glucose control, an early sinonasal evaluation, and public health initiatives are needed to decrease morbidity and mortality associated with this deadly condition in this vulnerable population.