COVID-19 Induces Body Composition and Metabolic Alterations

Interferon Upregulation Associates with Insulin Resistance in Humans

In humans, insulin resistance is a physiological response to infections developed to supply sufficient energy to the activated immune system. This metabolic adaptation facilitates the immune response but usually persists after the recovery period of the infection and predisposes the hosts to type 2 diabetes and vascular injury. In patients with diabetes, superimposed insulin resistance worsens metabolic control and promotes diabetic ketoacidosis. Pathogenic mechanisms underlying insulin resistance during microbial invasions remain to be fully defined. However, interferons cause insulin resistance in healthy subjects and other population groups, and their production is increased during infections, suggesting that this group of molecules may contribute to reduced insulin sensitivity. In agreement with this notion, gene expression profiles (transcriptomes) from patients with insulin resistance show a robust overexpression of interferon- stimulated genes (interferon signature). In addition, serum levels of interferon and surrogates for interferon activity are elevated in patients with insulin resistance. Circulating levels of interferon- γ-inducible protein-10, neopterin, and apolipoprotein L1 correlate with insulin resistance manifestations, such as hypertriglyceridemia, reduced HDL-c, visceral fat, and homeostasis model assessment-insulin resistance. Furthermore, interferon downregulation improves insulin resistance. Antimalarials such as hydroxychloroquine reduce interferon production and improve insulin resistance, reducing the risk for type 2 diabetes and cardiovascular disease. In addition, diverse clinical conditions that feature interferon upregulation are associated with insulin resistance, suggesting that interferon may be a common factor promoting this adaptive response. Among these conditions are systemic lupus erythematosus, sarcoidosis, and infections with severe acute respiratory syndrome-coronavirus-2, human immunodeficiency virus, hepatitis C virus, and Mycobacterium tuberculosis.

The prognostic significance of insulin resistance in COVID-19: a review

Objectives

Emerging publications indicate that diabetes predisposes patients with COVID-19 to more severe complications, which is partly attributed to inflammatory condition. In the current review, we reviewed recent published literature to provide evidence on the role of insulin resistance (IR) in diabetes, the association between diabetes and COVID-19 severity and mortality, the impact of COVID-19 infection on incident new-onset diabetes, mechanisms responsible for IR in COVID-19 patients, and the predictive value of different surrogates of IR in COVID-19.

Method

The literature search performs to find out studies that have assessed the association between IR surrogates and morbidity and mortality in patients with COVID-19.

Results

We showed that there is a bulk of evidence in support of the fact that diabetes is a potent risk factor for enhanced morbidity and mortality in COVID-19 patients. COVID-19 patients with diabetes are more prone to remarkable dysglycemia compared to those without diabetes, which is associated with an unfavourable prognosis. Furthermore, SARS-COV2 can make patients predispose to IR and diabetes via activating ISR, affecting RAAS signaling pathway, provoking inflammation, and changing the expression of PPARɣ and SREBP-1. Additionally, higher IR is associated with increased morbidity and mortality in COVID-19 patients and different surrogates of IR can be utilized as a prognostic biomarker for COVID-19 patients.

Conclusion

Different surrogates of IR can be utilized as predictors of COVID-19 complications and death.

Diabetes Mellitus, Energy Metabolism, and COVID-19

Obesity, diabetes mellitus (mostly type 2), and COVID-19 show mutual interactions because they are not only risk factors for both acute and chronic COVID-19 manifestations, but also because COVID-19 alters energy metabolism. Such metabolic alterations can lead to dysglycemia and long-lasting effects. Thus, the COVID-19 pandemic has the potential for a further rise of the diabetes pandemic. This review outlines how preexisting metabolic alterations spanning from excess visceral adipose tissue to hyperglycemia and overt diabetes may exacerbate COVID-19 severity. We also summarize the different effects of SARS-CoV-2 infection on the key organs and tissues orchestrating energy metabolism, including adipose tissue, liver, skeletal muscle, and pancreas. Last, we provide an integrative view of the metabolic derangements that occur during COVID-19. Altogether, this review allows for better understanding of the metabolic derangements occurring when a fire starts from a small flame, and thereby help reducing the impact of the COVID-19 pandemic.