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Blood Glucose Control Affects Morbidity and Mortality in COVID-19

Aug 18, 2020
Editor: Steve Freed, R.PH., CDE

Author: Sameen Khan, Pharm.D. Candidate, USF College of Pharmacy

A new study shows that patients with well-controlled blood glucose levels, defined as 70-72mg/dL.(3.9-10 mmol/L), have better COVID-19 treatment outcomes. 

The novel COVID-19 is a highly contagious coronavirus that has caused infection in such high capacity that within months the world is facing a global pandemic. The virus primarily affects the respiratory tract and lungs, causing pneumonia, and severe cases quickly progress to acute respiratory distress syndrome (ARDS), septic shock, and multiple organ dysfunction syndromes (MODS). Those at higher risk for developing severe cases leading to higher mortality rates are the elderly, immunocompromised, and those with preexisting conditions such as diabetes mellitus, hypertension, cardiovascular disease, and cancer.  Type 2 diabetes mellitus (T2DM), a pandemic itself, has become the second most prevalent COVID-19 comorbidity. A Chinese study published in June 2020 in the journal Cell Metabolism investigated the correlation between plasma glucose levels and clinical outcomes of COVID-19.  


Aims of this longitudinal retrospective cohort study were to provide a larger-scale analysis of the relationship between blood glucose and COVID-19 outcomes than has previously been done.  Patients included in the study had confirmed cases of COVID-19, as reported from nineteen hospitals in the province of Hubei, China. Exclusion criteria included those less than 18 or greater than 75 years of age, incomplete medical records, type 1 diabetes, history of gestational or drug-induced diabetes, severe congestive heart failure, and pregnancy. Patients with acute cases of myocardial infarction, pulmonary embolism, stroke, severe pancreatitis, and acute coronary syndrome were excluded from the study. This provided researchers with a cohort of 7,337 COVID-19 patients whose records were used in the study. Of the 7,337, 952 had a diagnosis of T2DM (13%).  The T2DM subset was further divided by their blood glucose control into 250 patients with well-controlled blood glucose, defined as 70-180mg/dL.(3.9-10.0 mmol/L), and 250 patients with poorly controlled blood glucose chosen for analysis in the study.  Differences in outcomes of morbidity and mortality between the groups were then analyzed.  

Patients with well-controlled blood glucose levels were shown to have better outcomes and required less intensive therapy. Compared to their poorly controlled counterparts, those whose blood glucose was well-controlled had fewer needs for pharmacological therapy, including antivirals (62.8% vs. 71.2%), antibiotics (53.2% vs. 66.5%), and corticosteroids (53.2% vs. 66.5%.) Patients with well-controlled blood glucose also required less oxygen inhalation (70.2% vs 83.5%), non-invasive ventilation (4.6% vs 11.9%), and invasive ventilation (0.0% vs 0.8%.) All-cause mortality was lower at 1.1% in the well-controlled blood glucose group compared with 11.0% of patients with poorly controlled blood glucose. Overall, the study was able to statistically show that after adjusting for age, gender, COVID-19 disease severity, and comorbidities, the hazard ratio for all-cause mortality of the well-controlled blood glucose group when compared to the poorly controlled blood glucose group was 0.13, reported with a 95% confidence interval.  

Overall, this study demonstrated that COVID-19 patients with uncontrolled blood glucose were at higher risk of morbidity and mortality, though it did have its limitations. All study participants were from one city in China, making it difficult to generalize for other populations. Data from the study was received from hospitals, so outpatient outcomes were not investigated. Researchers also accept that the study had a limited number of patients from which data could be extracted, so the study may not be appropriately powered to reflect a general population. Despite limitations, researchers were able to make use of available data to determine the extent to which glycemic parameters affect outcomes in COVID-19 patients. The fact that patients with uncontrolled hyperglycemia are at higher risk for morbidity and mortality when facing COVID-19 may have grave implications for a population such as the United States, in which 122.2 million people are diabetic or prediabetic, according to a 2020 report from the Centers for Disease Control and Prevention.  

Practice Pearls: 

  • If infected with COVID-19, patients with well-controlled glucose levels defined as 70-180mg/dL. (3.9-10 mmol/L) are at lower risk of morbidity and mortality  
  • Patients with well-controlled blood glucose had less need for antiviral or antibacterial drugs or corticosteroids. They also had fewer requirements for oxygen inhalation as well as invasive and non-invasive ventilation.  
  • This study provides grave implications in a country such as the United States in which the incidence of diabetes and prediabetes in the population is high. 


Zhu, Lihua, et al. “Association of Blood Glucose Control and Outcomes in Patients with COVID-19 and Preexisting Type 2 Diabetes.” Cell Metabolism, 1 May 2020, doi:10.1016/j.cmet.2020.04.021. 

“National Diabetes Statistics Report, 2020.” Diabetes, Centers for Disease Control and Prevention, February 11, 2020, www.cdc.gov/diabetes/library/features/diabetes-stat-report.html. 


Sameen Khan, Pharm.D. Candidate, USF College of Pharmacy 


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