Does the Hyperglycemia Impact on COVID-19 Outcomes Depend upon the Presence of Diabetes?—An Observational Study

Diabetes mellitus (DM) has emerged as a major risk factor for COVID-19 severity and SARS-CoV-2 infection can worsen glycemic control and may precipitate new-onset diabetes. At-admission hyperglycemia (AH) is a known predictor for worse outcomes in many diseases and seems to have a similar effect in COVID-19 patients. In this study, we aimed to assess the impact of AH regardless of pre-existing diabetes mellitus and new-onset diabetes diagnosis in the clinical severity of COVID-19 inpatients in the first months of the pandemic. A retrospective monocentric study on 374 COVID-19 inpatients (209 males) was developed to assess associations between AH (blood glucose levels in the Emergency Department or the first 24 h of hospitalization greater than 140 mg/dL) and severity outcomes (disease severity, respiratory support, admission to Intensive Care Unit (ICU) and mortality) in patients with and without diabetes. Considering diabetic patients with AH (N = 68;18.1%) there was a correlation with COVID-19 severity (p = 0.03), invasive mechanical ventilation (p = 0.008), and ICU admission (p = 0.026). No correlation was present with any severity outcomes in diabetic patients without AH (N = 33; 8.8%). All of the New-onset Diabetes patients (N = 15; 4%) had AH, and 12 had severe COVID-19; additionally, five patients were admitted to the ICU and three patients died. However, severity outcomes did not reach statistical correlation significance in this group. In nondiabetic patients with AH (N = 51; 13.6%), there was a statistically significant association with the need for oxygen therapy (p = 0.001), invasive mechanical ventilation (p = 0.01), and ICU admission (p = 0.03). Our results support data regarding the impact of AH on severity outcomes. It also suggests an effect of AH on the prognosis of COVID-19 inpatients, regardless of the presence of pre-existing diabetes or new-onset diabetes. We reinforce the importance to assess at admission glycemia in all patients admitted with COVID-19.