Beyond the Infection: Metabolic Imprints of Long COVID

Abstract

Aims: This systematic review aimed to investigate the association between long COVID and metabolic dysfunctions such as diabetes mellitus (DM), obesity, and dyslipidemias, with emphasis on the underlying pathophysiological mechanisms. Study Design: Systematic review. Place and Duration of Study: Searches were conducted between January and May 2024 across PubMed/MEDLINE, Scopus, and the Virtual Health Library (BVS) databases, considering publications from 2019 to 2024. Methodology: The review followed the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The PICO strategy guided the formulation of the research question. Eligible studies included observational and interventional designs that assessed metabolic outcomes in patients with long COVID. Although the search timeframe began in 2019, no eligible studies were found from 2019 and 2020, as the prolonged effects of COVID-19 had not yet been described in the scientific literature. A total of eight studies published between 2021 and 2024 met the inclusion criteria and were critically analyzed regarding design, level of evidence, and main findings. Results: The included studies consistently reported persistent metabolic alterations in patients with long COVID, including insulin resistance, chronic inflammation, lipid dysfunctions, and elevated laboratory markers (ferritin, CRP, HbA1c). Additionally, cognitive impairments and reduced quality of life were frequently observed. However, sample sizes across studies were generally small, and heterogeneity in methodology limited direct comparisons. Conclusion: Long COVID represents a complex condition with significant metabolic manifestations. The current evidence highlights the need for larger, longitudinal, and controlled studies to deepen understanding of the mechanisms involved and to support the development of effective post-COVID care strategies.