Poor Glycemic Control for Patients With Type 2 Diabetes Increases Risk of Long COVID Symptoms
The increased risk of symptoms only includes respiratory-related symptoms or brain fog.
Poor glycemic control for patients with type 2 diabetes (T2D) has been associated with a higher risk of long COVID symptoms for 30 to 180 days following COVID-19 infection, according to results of a study published in BMJ Open Diabetes Research and Care. Investigators noted that the risk increased as hemoglobin A1c levels rose.1
Investigators noted that long COVID can affect pulmonary and extra-pulmonary organ manifestations, which can include the development of diabetes. | Image Credit: Przemyslaw Iciak | stock.adobe.com
There have been approximately 193 million COVID-19 infections across the Americas from January 2020 to February 2025, according to the World Health Organization. Diabetes has been identified as a risk factor for COVID-19, contributing to severity and mortality. Patients with diabetes can also have complications, such as acute respiratory distress syndrome and multiorgan failure, according to the authors of a review published in Pathogens.2,3
As for long COVID, investigators noted that it can affect pulmonary and extra-pulmonary organ manifestations, which can include the development of diabetes. Study results show that diabetes and glucometabolic abnormalities have been reported during long COVID, and the incidence of diabetes is higher for patients who have had long COVID after 30 days. However, the study authors did not discuss the effects of diabetes on long COVID, only how long COVID affects diabetes.3
In the current analysis, investigators conducted a retrospective cohort using natural language processing (NLP) data from the National COVID Cohort Collaborative database to determine the association between the development of long COVID or death and hemoglobin A1c levels following 30 to 180 days post-COVID infection. Data for the patients included the index date, defined by a COVID-19 diagnosis code or laboratory test between January 1, 2021, and June 30, 2022, a preindex T2D diagnosis, at least 1 hemoglobin A1c measurement in the 6 months prior to and 7 days after the index date, at least 2 clinical notes analyzed by NLP in the 30 to 180 days post-index date, and at least 3 health care visits or death in the time period after the index date.
The primary end point of the study included either long COVID or death in the 30 to 180 days post-diagnosis.1
Investigators included 7430 patients with positive COVID diagnoses and T2D, with 54.3% being women, 59.9% were White, 17.8% were Black, and 23.3% were Hispanic or Latino. The overall rate of the composite outcome of long COVID or death was 23.9%. The study authors reported that in the COVID-19 positive group, the risk of patients with hemoglobin A1c ranges of 8% to below 10% and greater than 10% was higher than for patients with a hemoglobin A1c range of 6.5% to below 8%.The risk was also greater for patients with severe liver disease, cancer, dementia, and patients who used insulin.1
For symptom category, patients with hemoglobin A1c rates 8% or greater had an increased risk of respiratory and brain fog symptoms. There were no differences in risk for hemoglobin A1c and other symptom categories.1
The investigators also noted that the risk was lower for patients who were using metformin, glucagon-like peptide-1 medication, sodium-glucose cotransporter 2 inhibitors, and those who were younger. Patients who were hospitalized during their infection had a greater risk of death during the long COVID period, a greater risk of symptomatic long COVID, and a greater composite outcome of death or long COVID compared to individuals who were not hospitalized. Of note, there was no increased risk of death between hemoglobin A1c ranges.1
The study authors concluded, “While it is challenging to create and validate NLP data pipelines in clinical data, this study serves as a use case that highlights why text data from clinical notes are important for studying emerging diseases with heterogeneous presentations such as Long COVID.” They also stated that poor glycemic control does increase the risk of developing long COVID after an infection, specifically with respiratory symptoms and brain fog.1
