Admission Hyperglycemia—An Early Predictor of Severity and Poor Prognosis in COVID-19

Background/Objectives: Admission hyperglycemia is frequent in COVID-19 and may serve as an early marker of severity. We assessed whether admission hyperglycemia predicts severe disease and poor outcomes in adults without diabetes. Methods: We performed a retrospective cohort study at the Clinical Hospital of Pneu-mophthisiology and Infectious Diseases, Brașov, Romania, including adults hospital-ized with RT-PCR/antigen–confirmed COVID-19 between August 2020 and July 2021. Patients < 18 or >80 years, with prior diabetes, or on corticosteroids were excluded. Hyperglycemia was defined as fasting glucose >106 mg/dL and classified as mild (107–180 mg/dL), moderate (181–300 mg/dL), and severe (>300 mg/dL). Clinical, laboratory, imaging, treatment, utilization, and cost parameters were analyzed. Results: Of 1,009 patients, 734 (72.7%) were hyperglycemic at admission. Compared with normoglycemic patients, hyperglycemics more often developed respiratory fail-ure (67.7% vs. 38.2%), required CPAP (9.4% vs. 1.5%), had severe/critical disease (46.9% vs. 25.1%), ICU transfer (6.5% vs. 1.5%), and mortality (3.8% vs. 1.1%) (all p≤0.0256). They also showed lymphopenia, eosinopenia, higher inflammatory and co-agulation markers, longer hospitalization (12.1 vs. 10.1 days), and increased costs (€1,846 vs. €1,043) (all p< 0.001). Severe hyperglycemia (>300 mg/dL) strongly corre-lated with inflammation, coagulopathy, tissue injury, and radiologic severity. Conclusions: Admission hyperglycemia is a robust, easily measurable predictor of se-vere COVID-19 and adverse outcomes in non-diabetic adults and is associated with greater resource utilization and higher costs. Early identification may improve risk stratification, while prospective studies should assess whether glycemic control modi-fies prognosis. Keywords: COVID-19; SARS-CoV-2; admission hyperglycemia; severity; mortality; ICU;