BACKGROUND: COVID-19 is associated with morbidity and mortality, particularly among patients with metabolic comorbidities. Diabetes mellitus may adversely affect COVID-19 outcomes. This study aimed to compare demographic, clinical, laboratory, renal, inflammatory, treatment-related, and mortality-related characteristics between COVID-19 patients with and without diabetes.

MATERIAL AND METHODS: This retrospective observational study included 400 hospitalized COVID-19 patients classified as diabetic or non-diabetic using hospital records. Demographic characteristics, comorbidities, clinical presentations, laboratory findings, renal function markers, acute kidney injury, treatment variables, systemic immune-inflammation index (SII), and 90-day all-cause mortality were compared. ROC analysis assessed the discriminatory ability of admission SII for predicting 90-day mortality, and multivariable logistic regression was performed.

RESULTS: A total of 400 patients were included, including 130 with diabetes and 270 without. Patients in the diabetic group were older and had higher rates of hypertension and coronary artery disease. Respiratory symptoms and pneumonia were more frequent in the diabetic group. Renal function markers were significantly higher in the diabetic group; however, acute kidney injury, ICU admission, mechanical ventilation rates, and SII did not differ significantly between groups. During 90-day follow-up, mortality was higher in the diabetic group (15.4% vs 8.1%; P=0.030). In multivariable analysis, age, coronary artery disease, and SII greater than 2135.28 were associated with 90-day mortality. Admission SII showed modest discriminatory ability for predicting mortality (AUC=0.623; P=0.015).

CONCLUSIONS: Among patients hospitalized with COVID-19, diabetes was associated with higher comorbidity burden, respiratory involvement, altered renal function markers, and higher unadjusted 90-day mortality. Adjusted mortality was associated with age, coronary artery disease, and high admission SII.

Keywords: COVID-19, Diabetes Mellitus, Kidney Failure, Chronic, inflammation, renal insufficiency