# Admission Hyperglycemia as an Early Predictor of Severity and Poor Prognosis in COVID-19: A Retrospective Cohort Study of Hospitalized Adults

## TL;DR

High blood sugar at hospital admission predicts severe illness and worse outcomes in non-diabetic adults with COVID-19.

## Contribution

Identifies admission hyperglycemia as a novel early predictor of severe disease and poor prognosis in non-diabetic hospitalized adults with COVID-19.

## Key findings

- Hyperglycemic patients had higher rates of respiratory failure, ICU transfer, and mortality compared to normoglycemic patients.
- Severe hyperglycemia correlated with increased inflammation, coagulopathy, and radiologic severity in hospitalized adults with COVID-19.
- Hyperglycemia was associated with longer hospital stays and higher healthcare costs in non-diabetic patients.

## Abstract

Background/Objectives: Admission hyperglycemia is frequent in COVID-19, reflecting stress hyperglycemia, systemic inflammation, and potential viral injury to pancreatic β-cells. It 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 including adults hospitalized 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 1009 patients, 734 (72.7%) were hyperglycemic at admission. Compared with normoglycemic patients, hyperglycemics more often developed respiratory failure (67.7% vs. 38.2%), required CPAP (9.4% vs. 1.5%), and 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 coagulation markers, longer hospitalization (12.1 vs. 10.1 days), and increased costs (EUR 1846 vs. 1043) (all p < 0.001). Severe hyperglycemia (>300 mg/dL) strongly correlated with inflammation, coagulopathy, tissue injury, and radiologic severity. Conclusions: Admission hyperglycemia is a robust, easily measurable predictor of severe 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. Future prospective studies should determine whether early detection and aggressive glycemic control can modify prognosis.