key: cord-0788264-gt000k5l
authors: Sathish, Thirunavukkarasu; Cao, Yingting
title: What is the role of admission HbA1c in managing COVID‐19 patients?
date: 2020-12-22
journal: J Diabetes
DOI: 10.1111/1753-0407.13140
sha: 8a0b429a004a225e8ec738be186cc345ca9f00e4
doc_id: 788264
cord_uid: gt000k5l

nan

To the Editor, Some recent articles published in the Journal of Diabetes have raised concerns about the importance of checking glycosylated hemoglobin (HbA1c) upon hospital admission for coronavirus disease 2019 (COVID- 19) patients. [1] [2] [3] It is now undoubtedly clear that absolute hyperglycemia at the time of admission increases the risk of severe outcomes of COVID-19, independent of prior diabetes status, 4, 5 and tight glycemic control improves the prognosis of these patients significantly. 4, 5 However, the role of admission HbA1c, which reflects average glycemia over the preceding 2 to 3 months, in the management of COVID-19 patients remains uncertain.

Some studies have shown a significant association between admission HbA1c and disease progression or mortality in COVID-19 patients, whereas a few others did not (Table 1) . While the reasons for this discrepancy are not clear, most of these studies are constrained by a small number of patients, 6,7 a large proportion of missing HbA1c data, 8 and inadequate adjustment of potential confounders. 8, 9 Previous research has shown that background glycemia mediates the association between admission glucose and outcomes in patients with a variety of medical conditions. 10-12 Thus, correcting admission glucose levels for background glycemia estimated by HbA1c, the so-called relative hyperglycemia predicts outcomes in acute health conditions better than absolute hyperglycemia, 10, 13 albeit not yet proven in the COVID-19 context. Since HbA1c is relatively unaffected by the stress of acute illness, 14 it may help identify newly diagnosed diabetes cases in COVID-19 patients. Newly diagnosed diabetes (new onset or previously undiagnosed) is now increasingly recognized as a common phenomenon in COVID-19 patients. 15, 16 More importantly, COVID-19 patients with newly diagnosed diabetes appear to be at a greater risk for poor prognosis not only compared with those without diabetes but also individuals with known diabetes. [17] [18] [19] To summarize, admission blood glucose is certainly a key biomarker to risk stratify and guide the clinical management of COVID-19 patients, with or without known diabetes. Thus, it is essential that all COVID-19 patients be screened for absolute hyperglycemia upon admission so that early and appropriate treatment can be initiated if required. While the role of admission HbA1c as a marker of COVID-19 severity is yet to be fully established, HbA1c assists in identifying patients with newly diagnosed diabetes. 15, 20 These patients are a high-risk group and should be closely monitored for the emergence of cardiometabolic disorders in the long term. 16 

Elevated fasting blood glucose within the first week of hospitalization was associated with progression to severe illness of COVID-19 in patients with preexisting diabetes: a multicenter observational study

Response to: is newly diagnosed diabetes a stronger risk factor than pre-existing diabetes for COVID-19 severity?

Does glycemic control affect outcome of COVID-19?

COVID-19 in people with diabetes: understanding the reasons for worse outcomes

COVID-19 and diabetes mellitus: from pathophysiology to clinical management

The association of diabetes and the prognosis of COVID-19 patients: a retrospective study

Glycemic control before admission is an important determinant of prognosis in patients with coronavirus disease 2019

Phenotypic characteristics and prognosis of inpatients with COVID-19 and diabetes: the CORONADO study

Glycosylated hemoglobin is associated with systemic inflammation, hypercoagulability, and prognosis of COVID-19 patients

Relative hyperglycemia is an independent determinant of in-hospital mortality in patients with critical illness

Stress hyperglycemia and prognosis of stroke in nondiabetic and diabetic patients: a systematic overview

Stress hyperglycaemia and increased risk of death after myocardial infarction in patients with and without diabetes: a systematic overview

Relative hyperglycemia, a marker of critical illness: introducing the stress hyperglycemia ratio

Glycated hemoglobin A1c levels are not affected by critical illness

Proportion of newly diagnosed diabetes in COVID-19 patients: a systematic review and meta-analysis

Potential metabolic and inflammatory pathways between COVID-19 and new-onset diabetes

Newly diagnosed diabetes is associated with a higher risk of mortality than known diabetes in hospitalized patients with COVID-19

Hyperglycemia without diabetes and newonset diabetes are both associated with poorer outcomes in COVID-19

Is newly diagnosed diabetes a stronger risk factor than pre-existing diabetes for COVID-19 severity?

Is newly diagnosed diabetes as frequent as preexisting diabetes in COVID-19 patients