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Impaired glucose metabolism in patients with diabetes, prediabetes, and obesity is associated with severe COVID-19

Our take —

This single-center prospective cohort study showed that diabetes mellitus, pre-diabetes mellitus, and high body mass index (BMI) were individually associated with poorer COVID-19 prognosis. New onset hyperglycemia was associated with severe COVID-19 illness in patients without diabetes mellitus, which may suggest that SARS-CoV-2 infection can interfere with glucose metabolism through mechanisms not yet explicated. As this study was non-randomized with a limited sample size and did not adjust for other potential causes of glucose dysregulation, confounding factors cannot be ruled out, and therefore findings should be interpreted with caution.

Study design

Prospective cohort

Study population and setting

This study prospectively followed 184 COVID-19 patients (n=177 with laboratory confirmation of SARS-CoV-2 infection; 7 based on clinical examination) admitted consecutively over the course of 7 weeks (March 16 to May 2, 2020) to a large suburban hospital in Livingston, New Jersey. Study patients were an average age of 64.4 years old, were 53.3% male, and had a racial and ethnic composition of 53.8% Black, 25.5% white, 6.5% Latino, and 6.0% Asian. The cohort had a high prevalence of metabolic disturbance at admission; 62.0% of patients had diagnosed diabetes mellitus (DM), 23.9% had prediabetes (preDM) and elevated fasting blood glucose (FBG), and 4.3% had BMI>30 with normal HbA1C. Patients unaware of a previous diagnosis of diabetes were diagnosed as having diabetes if their HbA1C > 6.4%, while new onset of diabetes was determined if patients experienced persistently elevated fasting blood glucose (FBG) > 125 mg/dL and required insulin therapy. The primary outcome of interest was severe COVID-19, as determined by need for intubation.

Summary of Main Findings

Compared to non-intubated patients, intubated patients demonstrated statistically higher mean BMI (29.3 kg/m^2 vs.32.2 [p=0.030]), mean HbA1C (7.2% vs. 8.0% [p=0.034]), and mean FBG (163.7 mg/dL vs. 238.0 mg/dL [p=0.013]). Patients with DM were also 7.2 times more likely to be intubated than non-DM patients. Additionally, FBG was markedly elevated upon admission in 23 patients with preDM and in 6 patients without DM and with normal HbA1C levels despite the absence of corticosteroid therapy, a factor known to be associated with brief increases in FBG, suggesting the progression of new onset glucose dysregulation

Study Strengths

This study included a racial and ethnically diverse study population representative of groups heavily impacted by COVID-19 morbidity and mortality. The study also ascertained clearly defined DM, preDM, and other metabolic statuses through a thorough medical record review.


This study took place at a single clinical care site in a suburban setting in New Jersey that is managed by one group of clinicians, which may limit generalizability to other clinical care settings. Also, the study only included symptomatic patients presenting at a hospital, many of whom were more likely to be admitted due to underlying health conditions; therefore, any findings may not be generalizable to individuals with more moderate or mild disease progression or those with fewer comorbidities. The study also included a relatively small number of participants (n=184), limiting the study’s ability to investigate associations with other outcomes such as mortality. No potential confounders were assessed.

Value added

To the best of our knowledge, this study is the first-reported clinical study to document evidence of new onset hyperglycemia associated with severe COVID-19 disease.

This review was posted on: 2 November 2020