Risk of Post-Acute Sequelae of SARS-CoV-2 Infection (PASC) Among Patients with Type 2 Diabetes Mellitus on Anti-Hyperglycemic Medications

Background: Observed activity of metformin in reducing the risk of severe COVID-19 suggests a potential use of the anti-hyperglycemic in the prevention of post-acute sequelae of SARS-CoV-2 infection (PASC). We assessed the 3-month and 6-month risk of PASC among patients with type 2 diabetes mellitus (T2DM) comparing metformin users to sulfonylureas (SU) or dipeptidyl peptidase-4 inhibitors (DPP4i) users.
Methods: We used de-identified patient level electronic health record data from the National Covid Cohort Collaborative (N3C) between October 2021 and April 2023. Participants were adults ≥ 18 years with T2DM who had at least one outpatient healthcare encounter in health institutions in the United States prior to COVID-19 diagnosis. The outcome of PASC was defined based on the presence of a diagnosis code for the illness or using a predicted probability based on a machine learning algorithm. We estimated the 3-month and 6-month risk of PASC and calculated crude and weighted risk ratios (RR), risk differences (RD), and differences in mean predicted probability.
Results: We identified 5596 (mean age: 61.1 years; SD: 12.6) and 1451 (mean age: 64.9 years; SD 12.5) eligible prevalent users of metformin and SU/DPP4i respectively. We did not find a significant difference in risk of PASC at 3 months (RR = 0.86 [0.56; 1.32], RD = − 3.06 per 1000 [− 12.14; 6.01]), or at 6 months (RR = 0.81 [0.55; 1.20], RD = − 4.91 per 1000 [− 14.75, 4.93]) comparing prevalent users of metformin to prevalent users of SU/ DPP4i. Similar observations were made for the outcome definition using the ML algorithm.
Conclusion: The observed estimates in our study are consistent with a reduced risk of PASC among prevalent users of metformin, however the uncertainty of our confidence intervals warrants cautious interpretations of the results. A standardized clinical definition of PASC is warranted for thorough evaluation of the effectiveness of therapies under assessment for the prevention of PASC.

Plain Language Summary: Previous research suggests that metformin, due to its anti-viral, anti-inflammatory, and anti-thrombotic properties may reduce the risk of severe COVID-19. Given the shared etiology of COVID-19 and the post-acute sequelae of SARS-CoV-2 (PASC), and the proposed inflammatory processes of PASC, metformin may also be a beneficial preventive option. We investigated the benefit of metformin for PASC prevention in a population of type 2 diabetes mellitus patients with a COVID-19 diagnosis who were on metformin or two other anti-hyperglycemic medications prior to infection with SARS-CoV-2. Our results were consistent with a reduction in the risk of PASC with the use of metformin, however, the imprecise confidence intervals obtained warrants further investigation of this association of the potential beneficial effect of metformin for preventing PASC in patients with medication-managed diabetes.