Glucose levels outside the range of 70-160 mg/dL and high glycemic variability raise the risk for adverse outcomes in people with diabetes and COVID-19, new research from China suggests.
The findings come from a retrospective study of readings from ‘flash’, or intermittently scanned continuous glucose monitoring (isCGM, FreeStyle Libre, Abbott Diabetes Care), in people with diabetes hospitalized with COVID-19 in Wuhan.
“Patients with diabetes and COVID-19 have an increased risk of adverse outcomes with glucose levels > 160 mg/dL and < 70 mg/dL and a high [coefficient of variation]. Therapies that improve these metrics of glycemic control may result in better prognoses for these patients,” say Yun Shen, MD, and coauthors in their article published online February 11 in Diabetes Care.
On the other hand, mean sensor glucose was not a significant predictor of adverse COVID-19 outcomes. This finding underscores the fact that A1c doesn’t reflect glycemic variability and can appear falsely normal in a person who has both frequent hyper- and hypoglycemia.
“The mean glucose level does not provide information on the magnitude of hyperglycemia, hypoglycemia, and glycemic variability,” whereas CGM does provide those data, say Shen, of the Shanghai Clinical Center for Diabetes, China, and colleagues.
First Study to Investigate Glycemic Thresholds of Risk in COVID-19
While several previous studies have demonstrated associations between hyperglycemia and adverse COVID-19 outcomes in hospitalized patients, this is the first to investigate the thresholds of glycemia above and below which the increased risk occurs.
The data are important, given the recent push towards increased use of CGM in hospital settings during the pandemic in order to minimize staff exposure.
The study included 35 patients with diabetes who were hospitalized in Leishenshan Hospital, a newly built, temporary, 1500-bed facility in Wuhan designed for patients with COVID-19. (The authors traveled from Shanghai to help out in Wuhan.)
All patients were monitored with isCGM during their stay, which averaged 10.2 days. The composite outcome — mechanical ventilation, admission to intensive care, or critical illness — occurred in 15 of the 35 patients. None died.
The percentage of time above glucose levels ranging from 140 to 200 mg/dL were all greater among those who met the criteria for the composite outcome compared with those who didn’t.
For time spent above 160 mg/dL, the percentages were 52.1% for those who met the criteria for the composite outcome versus 29.8% for those who didn’t (P < 0.01). Time below 70 mg/dL was also significantly longer in the group that met the criteria for the composite outcome compared with those who didn’t (4.43% vs 0.54%; P < .01).
After adjustments for multiple factors including age, sex, body mass index, symptoms on admission, blood pressure, and use of glucocorticoids, time above the range thresholds of 160-200 mg/dL and time spent below 70 mg/dL were significantly associated with increased odds for adverse composite outcomes of COVID-19.
Odds ratios ranged from 1.06 for > 160 mg/dL to 1.14 for > 200 mg/dL, and 6.56 for < 70 mg/dL.
Time spent above 160-200 mg/dL and below 70 mg/dL were also significantly associated with increased odds of prolonged hospitalization (over 30 days).
And the mean glucose level derived from isCGM was significantly higher among the patients who had a composite outcome (174 vs 144 mg/dL; P < .01). However, the overall linear association between mean sensor glucose and composite adverse outcomes was not statistically significant (odds ratio 2.0 after multiple adjustments).
The possible mechanism of the increased risk of COVID-19 and poor prognosis in patients with diabetes is thought to be related to neutrophil dysfunction, decreased T-cell immune response, and abnormal humoral immunity, the researchers say.
“Therefore, the combination of diabetes and COVID-19 may lead to a toxic milieu, resulting in more severe infection and death,” and those with glucose levels > 160 mg/dL and < 70 mg/dL and a high coefficient of variation, “have an increased risk of adverse outcomes,” they conclude.
The study was supported by the Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant and Shanghai Municipal Key Clinical Specialty. The isCGM and cloud platform-based system were partly supported by Abbott Diabetes Care. The authors had no further disclosures.
Diabetes Care. Published online February 11, 2021. Abstract