The impact of diabetes mellitus on morbidity and mortality in patients with COVID-19

By Dr. Liji Thomas, MDJul 31 2023Reviewed by Benedette Cuffari, M.Sc.

Diabetes mellitus (DM) influences morbidity and mortality rates in various populations throughout the world and has been recognized as a risk factor for severe coronavirus disease 2019 (COVID-19). A new study published in Viruses examines the impact of DM on post-COVID-19 clinical outcomes. 

Study: Diabetes mellitus and its association with adverse in-hospital outcomes in patients with COVID-19—A nationwide study. Image Credit: Alexandros Michailidis / Shutterstock.com

Introduction

During the COVID-19 pandemic, healthcare delivery was affected in various ways. For example, acute and chronic cardiovascular diseases (CVDs) and events were less frequently observed in hospitals, both because public health measures favored reduced contact between patients themselves as well as between patients and their healthcare providers.

Patients may have also developed a fear of contracting COVID-19 and becoming seriously ill, which may have also contributed to reduced rates of hospitalization for non-COVID-19 illnesses. Early on in the pandemic, DM was found to increase the risk of severe COVID-19; however, there remains a lack of data on the impact of DM on morbidity and mortality in hospitalized COVID-19 patients.

In the current study, researchers examine the health records of all hospitalized patients with a confirmed diagnosis of COVID-19 during 2020 in Germany. These patients were categorized by the degree of influence DM exerted on their mortality while in the hospital and the rate of adverse events.

What did the study show?

There were over 176,000 hospitalizations during the study period, 25% of whom had DM. A higher proportion of these patients were male, whose median age was seven years greater than for the rest of the study population. Monthly hospitalizations rose during the last four months of 2020 and were highest among elderly patients.

Diabetic COVID-19 patients were more likely to have CVD, chronic obstructive pulmonary disease (COPD), chronic kidney disease (CKD), and liver disease as compared to non-diabetic patients.

COVID-19 patients with DM were more likely to be sick with other conditions, as measured by the Charlson comorbidity index (CCI). More specifically, diabetic COVID-19 patients had a CCI of six, which was double that of non-DM patients.

Diabetic COVID-19 patients were associated with a 40%and 50% increased risk of pneumonia and acute respiratory distress syndrome (ARDS), respectively. Additionally, these patients had a 21-fold increased risk of intensive care unit (ICU) admission as compared to other hospitalized COVID-19 patients.

Outcomes like acute kidney failure and dialysis, as well as mechanical ventilation or extracorporeal membrane oxygenation (ECMO) requirements, were 50% more likely among patients with COVID-19 and DM. ECMO is a rare treatment approach; however, the use of this treatment rose from 0.8% to 1% in patients without and with DM, respectively.

The likelihood of major adverse cardiac and cerebrovascular events (MACCE) was 25% higher, as were the odds of dying in the hospital in COVID-19 patients with DM. While the fatality rate for each case was about one in seven for hospitalized COVID-19 patients without DM, it rose to about one in four with DM, whereas the fatality rate for MACCE rose from about one in six patients to more than 25%.

DM was also associated with a greater risk of stroke, heart attacks, and blood transfusion requirements. The association of DM with poor outcomes arises due to the increase in endothelial dysfunction, inflammation, oxidative stress, and poor immunological responses.

These physiological effects are characteristic of both conditions, which is consistent with a COVID-19-related exacerbation of injury mechanisms already operating in the presence of DM. These factors, which are closely linked to blood glucose levels, promote disease progression to more severe grades, such as organ damage, a higher chance of complications, and increased requirements for intensive care and therapies like mechanical ventilation.

What are the implications?

While DM does not appear to increase the risk of contracting COVID-19, it is a significant risk factor for severe illness. The increased likelihood of most adverse outcomes in hospitalized COVID-19 patients with DM emphasizes the need for careful medical protocols to ensure intensive care and monitoring during the hospitalization of these patients.

The study findings corroborate earlier research outside Germany, which has shown the risk of in-hospital case fatality in COVID-19 with DM to rise by two- to three-fold as compared to non-diabetic patients. DM contributed to about 10% and 17% of severe illness and death among COVID-19 patients, respectively, according to a review of almost 730 papers covering over 29 million patients.

The impact of DM on COVID-19 outcomes is greater in poorer regions that offer less access to healthcare services, where available services are often of less quality.

The coincidence of the two diseases leads to increased morbidity and mortality, underlining the need for particular focus on this vulnerable patient group.”