In a new study, researchers found that in patients with COVID-19 but without diabetes, abnormally high blood sugar is linked to more than double the risk of death and also an increased risk of severe complications.
The research was conducted by a team from Huazhong University of Science and Technology, China.
Previous studies have shown that hyperglycemia (abnormally high blood sugar) is linked to an elevated risk of mortality in community-acquired pneumonia, stroke, heart attacks, trauma and surgery, among other conditions.
A number of studies have also shown links between diabetes and poor outcomes in COVID-19 patients.
However, the direct correlation between fasting blood glucose (FBG) level at admission to hospital and clinical outcomes of COVID-19 patients without diagnosed diabetes has not been known.
In this new study, the team examined the association between FBG on admission and the 28-day mortality of COVID-19 patients without previously diagnosed diabetes in two hospitals.
They assessed all COVID-19 patients with a known outcome at 28-days and FBG measurement at admission from 24 January 2020 to 10 February 2020 in two hospitals based in Wuhan, China.
Demographic and clinical data, 28-day outcomes, in-hospital complications, and CRB-65 scores of COVID-19 patients in the two hospitals were analyzed.
The CRB-65 score is an effective measure for assessing the severity of pneumonia and is based on four indicators: level of confusion, respiratory rate (over 30 breaths per min), systolic blood pressure (90 mmHg or less) or diastolic blood pressure (60 mmHg or less), and age (65 years or over).
A total of 605 COVID-19 patients were enrolled, including 114 who died in hospital.
A total of 208 (34%) had one or more underlying conditions (but not diagnosed diabetes), of which high blood pressure was the most common.
Almost one third (29%) of patients fell into the highest category of FBG on admission which if found consistently would result in a diagnosis of type 2 diabetes.
A further 17% were in the range that would be considered pre-diabetic, while more than half (54%) were in the ‘normal’ FBG range.
The results showed that patients in the highest FBG group were 2.3 times more likely to die than those in the lowest, a statistically significant result.
Those in the middle (pre-diabetic) FBG group were 71% more likely to die than those in the lowest group, although this result only had borderline statistical significance.
The data also showed that men were 75% more likely to die than women; and that patients with higher CRB65 scores (and thus worse pneumonia) were also at higher risk of death.
This study shows, for the first time, that elevated blood sugar level at admission is strongly linked to increased mortality and complications in COVID-19 patients without a previous diagnosis of diabetes.
The authors suggest that possible mechanisms for this increased mortality include hyperglycemia-induced changes in coagulation (clotting), worsening of endothelial function (the function of the walls of blood vessels), and overproduction of inflammatory cytokines produced by the immune system (the so-called cytokine storm).
One author of the study is Dr. Yang Jin, Union Hospital, and Tongji Medical College.
The study is published in Diabetologia.
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