Metformin Use in Diabetes Prior to Hospitalization: Effects on Mortality in Covid-19

Metformin as a Therapeutic Agent for Obesity-Associated Immune Dysfunction

Obesity is associated with impaired immune function, characterized by inflammation, and leading to poor response to infection, impaired vaccine response, increased susceptibility to autoimmune disease, and increased risk of cancer and cancer mortality. Worse, there is evidence that weight loss alone may be insufficient to reverse the immune dysfunction caused by obesity. It is therefore critically important to identify alternative therapeutic approaches to decrease the negative effects of obesity-associated inflammation. In this article, we will review evidence that the antidiabetic drug metformin may be considered as a therapeutic agent for obesity-associated immune dysfunction. Metformin has immunomodulatory effects, stimulating or suppressing the immune response in both a cell-specific and disease-specific manner. Although the mechanism of action of metformin on the immune system remains to be fully elucidated, there is strong evidence that metformin enters select immune cells and disrupts electron transport, leading to both AMP-activated protein kinase (AMPK)-dependent and AMPK-independent effects on immune cell differentiation and cytokine production. These effects of metformin on immune cells have been shown to improve immune responses to infection, autoimmunity, and cancer.

Association of Metformin, Dipeptidyl Dipeptidase-4 Inhibitors, and Insulin with Coronavirus Disease 2019-Related Hospital Outcomes in Patients with Type 2 Diabetes

OBJECTIVE

The effects of diabetes medications on COVID-19 hospitalization outcomes have not been consistent. We sought to determine the effect of metformin, dipeptidyl peptidase-4 inhibitors (DPP-4i), and insulin on admission to the intensive care unit (ICU), need for assisted ventilation, development of renal insufficiency, and mortality in patients admitted with COVID-19 infection after controlling for clinical variables and other relevant diabetes-related medications in patients with type 2 diabetes mellitus (DM).

METHODS

This was a retrospective study of patients hospitalized with COVID-19 from a single hospital system. Univariate and multivariate analyses were performed that included demographic data, glycated hemoglobin, kidney function, smoking status, insurance, Charlson comorbidity index, number of diabetes medications, and use of angiotensin-converting enzyme inhibitors and statin prior to admission and glucocorticoids during admission.

RESULTS

A total of 529 patients with type 2 DM were included in our final analysis. Neither metformin nor DPP4i prescription was associated with ICU admission, need for assisted ventilation, or mortality. Insulin prescription was associated with increased ICU admission but not with need for assisted ventilation or mortality. There was no association of any of these medications with development of renal insufficiency.

CONCLUSIONS

In this population, limited to type 2 DM and controlled for multiple variables that have not been consistently studied (such as a measure of general health, glycated hemoglobin, and insurance status), insulin prescription was associated with increased ICU admission. Metformin and DPP4i prescriptions did not have an association with the outcomes.

The Impact of GLP-1 RAs and DPP-4is on Hospitalisation and Mortality in the COVID-19 Era: A Two-Year Observational Study

Novel antidiabetic drugs have the ability to produce anti-inflammatory effects regardless of their glucose-lowering action. For this reason, these molecules (including GLP-1 RAs and DPP-4is) were hypothesized to be effective against COVID-19, which is characterized by cytokines hyperactivity and multiorgan inflammation. The aim of our work is to explore the potential protective role of GLP-1 RAs and DPP-4is in COVID-19 (with the disease intended to be a model of an acute stressor) and non-COVID-19 patients over a two-year observation period. Retrospective and one-versus-one analyses were conducted to assess the impact of antidiabetic drugs on the need for hospitalization (in both COVID-19- and non-COVID-19-related cases), in-hospital mortality, and two-year mortality. Logistic regression analyses were conducted to identify the variables associated with these outcomes. Additionally, log-rank tests were used to plot survival curves for each group of subjects, based on their antidiabetic treatment. The performed analyses revealed that despite similar hospitalization rates, subjects undergoing home therapy with GLP-1 RAs exhibited significantly lower mortality rates, even over a two-year period. These individuals demonstrated improved survival estimates both within hospital and non-hospital settings, even during a longer observation period.

Risk phenotypes of diabetes and association with COVID-19 severity and death: an update of a living systematic review and meta-analysis

AIMS/HYPOTHESIS

To provide a systematic overview of the current body of evidence on high-risk phenotypes of diabetes associated with COVID-19 severity and death.

METHODS

This is the first update of our recently published living systematic review and meta-analysis. Observational studies investigating phenotypes in individuals with diabetes and confirmed SARS-CoV-2 infection with regard to COVID-19-related death and severity were included. The literature search was conducted from inception up to 14 February 2022 in PubMed, Epistemonikos, Web of Science and the COVID-19 Research Database and updated using PubMed alert to 1 December 2022. A random-effects meta-analysis was used to calculate summary relative risks (SRRs) with 95% CIs. The risk of bias was evaluated using the Quality in Prognosis Studies (QUIPS) tool and the certainty of evidence using the GRADE approach.

RESULTS

A total of 169 articles (147 new studies) based on approximately 900,000 individuals were included. We conducted 177 meta-analyses (83 on COVID-19-related death and 94 on COVID-19 severity). Certainty of evidence was strengthened for associations between male sex, older age, blood glucose level at admission, chronic insulin use, chronic metformin use (inversely) and pre-existing comorbidities (CVD, chronic kidney disease, chronic obstructive pulmonary disease) and COVID-19-related death. New evidence with moderate to high certainty emerged for the association between obesity (SRR [95% CI] 1.18 [1.04, 1.34], n=21 studies), HbA1c (53-75 mmol/mol [7-9%]: 1.18 [1.06, 1.32], n=8), chronic glucagon-like peptide-1 receptor agonist use (0.83 [0.71, 0.97], n=9), pre-existing heart failure (1.33 [1.21, 1.47], n=14), pre-existing liver disease (1.40 [1.17, 1.67], n=6), the Charlson index (per 1 unit increase: 1.33 [1.13, 1.57], n=2), high levels of C-reactive protein (per 5 mg/l increase: 1.07 [1.02, 1.12], n=10), aspartate aminotransferase level (per 5 U/l increase: 1.28 [1.06, 1.54], n=5), eGFR (per 10 ml/min per 1.73 m2 increase: 0.80 [0.71, 0.90], n=6), lactate dehydrogenase level (per 10 U/l increase: 1.03 [1.01, 1.04], n=7) and lymphocyte count (per 1×109/l increase: 0.59 [0.40, 0.86], n=6) and COVID-19-related death. Similar associations were observed between risk phenotypes of diabetes and severity of COVID-19, with some new evidence on existing COVID-19  vaccination status (0.32 [0.26, 0.38], n=3), pre-existing hypertension (1.23 [1.14, 1.33], n=49), neuropathy and cancer, and high IL-6 levels. A limitation of this study is that the included studies are observational in nature and residual or unmeasured confounding cannot be ruled out.

CONCLUSIONS/INTERPRETATION

Individuals with a more severe course of diabetes and pre-existing comorbidities had a poorer prognosis of COVID-19 than individuals with a milder course of the disease.

REGISTRATION

PROSPERO registration no. CRD42020193692.

PREVIOUS VERSION

This is a living systematic review and meta-analysis. The previous version can be found at https://link.springer.com/article/10.1007/s00125-021-05458-8 FUNDING: The German Diabetes Center (DDZ) is funded by the German Federal Ministry of Health and the Ministry of Culture and Science of the State North Rhine-Westphalia. This study was supported in part by a grant from the German Federal Ministry of Education and Research to the German Center for Diabetes Research (DZD).

Senotherapeutics: An emerging approach to the treatment of viral infectious diseases in the elderly

In the context of the global COVID-19 pandemic, the phenomenon that the elderly have higher morbidity and mortality is of great concern. Existing evidence suggests that senescence and viral infection interact with each other. Viral infection can lead to the aggravation of senescence through multiple pathways, while virus-induced senescence combined with existing senescence in the elderly aggravates the severity of viral infections and promotes excessive age-related inflammation and multiple organ damage or dysfunction, ultimately resulting in higher mortality. The underlying mechanisms may involve mitochondrial dysfunction, abnormal activation of the cGAS-STING pathway and NLRP3 inflammasome, the role of pre-activated macrophages and over-recruited immune cells, and accumulation of immune cells with trained immunity. Thus, senescence-targeted drugs were shown to have positive effects on the treatment of viral infectious diseases in the elderly, which has received great attention and extensive research. Therefore, this review focused on the relationship between senescence and viral infection, as well as the significance of senotherapeutics for the treatment of viral infectious diseases.

Is metformin use associated with low mortality in patients with type 2 diabetes mellitus hospitalized for COVID-19? a multivariable and propensity score-adjusted meta-analysis

BACKGROUND

Coronavirus disease 2019 (COVID-19) is a new pandemic that the entire world is facing since December of 2019. Increasing evidence has shown that metformin is linked to favorable outcomes in patients with COVID-19. The aim of this study was to address whether outpatient or inpatient metformin therapy for type 2 diabetes mellitus is associated with low in-hospital mortality in patients hospitalized for COVID-19.

METHODS

We searched studies published in PubMed, Embase, Google Scholar and Cochrane Library up to November 1, 2022. Raw event data extracted from individual study were pooled using the Mantel-Haenszel approach. Odds ratio (OR) or hazard ratio (HR) adjusted for covariates that potentially confound the association using multivariable regression or propensity score matching was pooled by the inverse-variance method. Random effect models were applied for meta-analysis due to variance among studies.

RESULTS

Twenty-two retrospective observational studies were selected. The pooled unadjusted OR for outpatient metformin therapy and in-hospital mortality was 0.48 (95% CI, 0.37-0.62) and the pooled OR adjusted with multivariable regression or propensity score matching was 0.71 (95% CI, 0.50-0.99). The pooled unadjusted OR for inpatient metformin therapy and in-hospital mortality was 0.18 (95% CI, 0.10-0.31), whereas the pooled adjusted HR was 1.10 (95% CI, 0.38-3.15).

CONCLUSIONS

Our results suggest that there is a significant association between the reduction of in-hospital mortality and outpatient metformin therapy for type 2 diabetes mellitus in patients hospitalized for COVID-19.

Association of Metformin with Mortality in COVID-19 Patients: A Systematic Review and Meta-Analysis

Studies have demonstrated high prevalence of mortality in coronavirus disease (COVID-19) patients with type 2 diabetes mellitus; however, the effects of antidiabetic pharmacotherapy on COVID-19 complications need further exploration. The aim of the study was to explore the association of metformin use and mortality in COVID-19 patients. A literature search was conducted using the databases Medline (via PubMed) and Cochrane Central Register of Controlled Trials until February 09, 2021. Nine studies were included in the meta-analysis, including 12,684 COVID-19 patients. The meta-analysis suggested 37% lower risk of mortality in patients receiving metformin (risk ratio: 0.63; 95% confidence interval: 0.50–0.78; p < 0.001). However, no significant difference in hospitalization days between the two groups (p = 0.197) was observed. The analysis revealed significantly lower risk of having obesity (p < 0.001), hypertension (p < 0.001), heart failure (p < 0.001), and cerebrovascular disease (p = 0.015) in the group receiving metformin. The analysis also demonstrated significantly lower risk of using anticoagulants (p = 0.015), diuretics (p < 0.001), and antiplatelets (p = 0.010) in patients receiving metformin. Our findings suggest that metformin use decreases mortality in COVID-19 patients. However, randomized studies demonstrating the consequences of metformin use are needed to understand the magnitude of the beneficial effects of metformin.

Metformin in SARS-CoV-2 infection: A hidden path - from altered inflammation to reduced mortality. A review from the literature

SARS-CoV-2 infection has been a major threat to human health and a huge challenge to Medicine. In only two years, COVID-19 affected >350 million people, causing >5.6 million deaths. Chronic inflammatory states, such as diabetes or obesity, are known risk factors for COVID-19 poorest outcomes, with higher risk for disease severity and greater mortality. Metformin remains on the first line of the management of hyperglycemia in type 2 diabetes. Through its anti-inflammatory and immunomodulatory mechanisms, metformin appears as an opportunity to control the dysregulated cytokine storm secondary to SARS-CoV-2 infection. Recent studies point towards a potential protective role of metformin in the course of COVID-19, showing that current or previous treatment with metformin associates with better outcomes.

Whole patient knowledge modeling of COVID-19 symptomatology reveals common molecular mechanisms

Infection with SARS-CoV-2 coronavirus causes systemic, multi-faceted COVID-19 disease. However, knowledge connecting its intricate clinical manifestations with molecular mechanisms remains fragmented. Deciphering the molecular basis of COVID-19 at the whole-patient level is paramount to the development of effective therapeutic approaches. With this goal in mind, we followed an iterative, expert-driven process to compile data published prior to and during the early stages of the pandemic into a comprehensive COVID-19 knowledge model. Recent updates to this model have also validated multiple earlier predictions, suggesting the importance of such knowledge frameworks in hypothesis generation and testing. Overall, our findings suggest that SARS-CoV-2 perturbs several specific mechanisms, unleashing a pathogenesis spectrum, ranging from "a perfect storm" triggered by acute hyper-inflammation, to accelerated aging in protracted "long COVID-19" syndromes. In this work, we shortly report on these findings that we share with the community via 1) a synopsis of key evidence associating COVID-19 symptoms and plausible mechanisms, with details presented within 2) the accompanying "COVID-19 Explorer" webserver, developed specifically for this purpose (found at https://covid19.molecularhealth.com). We anticipate that our model will continue to facilitate clinico-molecular insights across organ systems together with hypothesis generation for the testing of potential repurposing drug candidates, new pharmacological targets and clinically relevant biomarkers. Our work suggests that whole patient knowledge models of human disease can potentially expedite the development of new therapeutic strategies and support evidence-driven clinical hypothesis generation and decision making.

Association of Glucose-Lowering Drugs With Outcomes in Patients With Diabetes Before Hospitalization for COVID-19: A Systematic Review and Network Meta-analysis

IMPORTANCE

Patients with COVID-19 have a high prevalence of diabetes, and diabetes and blood glucose control are determinants of intensive care unit admission and mortality.

OBJECTIVE

To evaluate the association between COVID-19-related adverse outcomes and 8 antihyperglycemic drugs in patients with diabetes who were subsequently diagnosed and hospitalized with COVID-19.

DATA SOURCES

Data were retrieved and collected in PubMed, Embase, Cochrane Central Register, Web of Science, and ClinicalTrials.gov from database inception to September 5, 2022.

STUDY SELECTION

For this systematic review and network meta-analysis, randomized clinical trials and observational studies conducted among patients with diabetes while receiving glucose-lowering therapies for at least 14 days before the confirmation of COVID-19 infection were included after blinded review by 2 independent reviewers and consultations of disagreement by a third independent reviewer. Of 1802 studies initially identified, 31 observational studies met the criteria for further analysis.

DATA EXTRACTION AND SYNTHESIS

This study follows the Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline. Bayesian network meta-analyses were performed with random effects.

MAIN OUTCOMES AND MEASURES

A composite adverse outcome, including the need for intensive care unit admission, invasive and noninvasive mechanical ventilation, or in-hospital death.

RESULTS

Thirty-one distinct observational studies (3 689 010 patients with diabetes hospitalized for COVID-19) were included. The sodium-glucose cotransporter-2 inhibitors (SGLT-2is) were associated with relatively lower risks of adverse outcomes compared with insulin (log of odds ratio [logOR], 0.91; 95% credible interval [CrI], 0.57-1.26), dipeptidyl peptidase-4 inhibitors (logOR, 0.61; 95% CrI, 0.28-0.93), secretagogues (logOR, 0.37; 95% CrI, 0.02-0.72), and glucosidase inhibitors (logOR, 0.50; 95% CrI, 0.00-1.01). Based on the surface under the cumulative ranking curves value, SGLT-2is were associated with the lowest probability for adverse outcomes (6%), followed by glucagon-like peptide-1 receptor agonists (25%) and metformin (28%). A sensitivity analysis revealed that the study was reliable.

CONCLUSIONS AND RELEVANCE

These findings suggest that the use of an SGLT-2i before COVID-19 infection is associated with lower COVID-19-related adverse outcomes. In addition to SGLT-2is, glucagon-like peptide-1 receptor agonists and metformin were also associated with relatively low risk of adverse outcomes.

Targeting T cell (oxidative) metabolism to improve immunity to viral infection in the context of obesity

Disorders of systemic metabolism can influence immunity. Individuals with obesity are known to have increased inflammation, increased risk to select autoimmune diseases, impaired response to several infections, and impaired vaccine response. For example, over the last decade, it has become clear that individuals with obesity have increased risk of morbidity and mortality from influenza infection. Unsurprisingly, this finding is also observed in the current COVID-19 pandemic: individuals with obesity, particularly severe obesity, have increased risk of poor outcomes from SARS-CoV-2 infection, including increased rates of hospitalization, ICU admission, mechanical ventilation, and death. Several studies have now demonstrated a critical role for T cells in the context of obesity-associated immune dysfunction in response to viral infection, and one mechanism for this may be altered T cell metabolism. Indeed, recent studies have shown that activated T cells from obese mice have an altered metabolic profile characterized by increased glucose oxidation, both in vitro and in vivo following viral infection. For that reason, treatments that target abnormal immune cell metabolism in obesity may improve outcomes to viral infection. To that end, several recent studies have shown that use of the metabolic drug, metformin, can reverse abnormal T cell metabolism and restore T cell immunity, as well as survival, in response to viral infection. These findings will be discussed in detail here.

The IL-1β, IL-6, and TNF cytokine triad is associated with post-acute sequelae of COVID-19

Post-acute sequelae of COVID-19 (PASC) is emerging as global problem with unknown molecular drivers. Using a digital epidemiology approach, we recruited 8,077 individuals to the cohort study for digital health research in Germany (DigiHero) to respond to a basic questionnaire followed by a PASC-focused survey and blood sampling. We report the first 318 participants, the majority thereof after mild infections. Of those, 67.8% report PASC, predominantly consisting of fatigue, dyspnea, and concentration deficit, which persists in 60% over the mean 8-month follow-up period and resolves independently of post-infection vaccination. PASC is not associated with autoantibodies, but with elevated IL-1β, IL-6, and TNF plasma levels, which we confirm in a validation cohort with 333 additional participants and a longer time from infection of 10 months. Blood profiling and single-cell data from early infection suggest the induction of these cytokines in COVID-19 lung pro-inflammatory macrophages creating a self-sustaining feedback loop.

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We report a post-COVID-19 digital epidemiology study with biomarker analysis (n = 651)

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PASC persists in 60% of participants up to 24 months after mild COVID-19

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PASC is associated with high IL-1β, IL-6, and TNF levels but not autoantibodies

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Overactivated monocytes/macrophages are likely the source of cytokine production

Preadmission use of antidiabetic medications and mortality among patients with COVID-19 having type 2 diabetes: A meta-analysis

BACKGROUND

Diabetes is an independent predictor of poor outcomes in patients with COVID-19. We compared the effects of the preadmission use of antidiabetic medications on the in-hospital mortality of patients with COVID-19 having type 2 diabetes.

METHODS

A systematic search of PubMed, EMBASE, Scopus and Web of Science databases was performed to include studies (except case reports and review articles) published until November 30, 2021. We excluded papers regarding in-hospital use of antidiabetic medications. We used a random-effects meta-analysis to calculate the pooled OR (95% CI) and performed a sensitivity analysis to confirm the robustness of the meta-analyses.

MAIN FINDINGS

We included 61 studies (3,061,584 individuals), which were rated as having low risk of bias. The OR (95% CI) indicated some medications protective against COVID-related death, including metformin [0.54 (0.47-0.62), I² 86%], glucagon-like peptide-1 receptor agonist (GLP-1RA) [0.51 (0.37-0.69), I² 85%], and sodium-glucose transporter-2 inhibitor (SGLT-2i) [0.60 (0.40-0.88), I² 91%]. Dipeptidyl peptidase-4 inhibitor (DPP-4i) [1.23 (1.07-1.42), I² 82%] and insulin [1.70 (1.33-2.19), I² 97%] users were more likely to die during hospitalization. Sulfonylurea, thiazolidinedione, and alpha-glucosidase inhibitor were mortality neutral [0.92 (95% CI 0.83-1.01, I² 44%), 0.90 (95% CI 0.71-1.14, I² 46%), and 0.61 (95% CI 0.26-1.45, I² 77%), respectively]. The sensitivity analysis indicated that our findings were robust.

CONCLUSIONS

Metformin, GLP-1RA, and SGLT-2i were associated with lower mortality rate in patients with COVID-19 having type 2 diabetes. DPP-4i and insulin were linked to increased mortality. Sulfonylurea, thiazolidinedione, and alpha-glucosidase inhibitors were mortality neutral. These findings can have a large impact on the clinicians' decisions amid the COVID-19 pandemic.

The Role of Diabetes and Hyperglycemia on COVID-19 Infection Course-A Narrative Review

It was previously reported that subjects with diabetes mellitus (DM) are more vulnerable to several bacterial or viral infections. In the era of coronavirus disease 2019 (COVID-19) pandemic, it is reasonable to wonder whether DM is a risk factor for COVID-19 infection, too. It is not yet clear whether DM increases the risk for contracting COVID-19 infection or not. However, patients with DM when infected are more likely to develop severe or even fatal COVID-19 disease course than patients without DM. Certain characteristics of DM patients may also deteriorate prognosis. On the other hand, hyperglycemia per se is related to unfavorable outcomes, and the risk may be higher for COVID-19 subjects without pre-existing DM. In addition, individuals with DM may experience prolonged symptoms, need readmission, or develop complications such as mucormycosis long after recovery from COVID-19; close follow-up is hence necessary in some selected cases. We here present a narrative review of the literature in order to set light into the relationship between COVID-19 infection and DM/hyperglycemia.

Korean Red Ginseng, a regulator of NLRP3 inflammasome, in the COVID-19 pandemic

Coronavirus disease 2019 (COVID-19) exhibits various symptoms, ranging from asymptomatic to severe pneumonia or death. The major features of patients in severe COVID-19 are the dysregulation of cytokine secretion, pneumonia, and acute lung injury. Consequently, it leads to acute respiratory distress syndrome, disseminated intravascular coagulation, multiple organ failure, and death. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative virus of COVID-19, influences nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 3 (NLRP3), the sensor of inflammasomes, directly or indirectly, culminating in the assembly of NLRP3 inflammasome and activation of inflammatory caspases, which induce the inflammatory disruption in severe COVID-19. Accordingly, the target therapeutics for inflammasome has attracted attention as a treatment for COVID-19. Korean Red Ginseng (KRG) inhibits several inflammatory responses, including the NLRP3 inflammasome signaling. This review discusses the role of KRG in the treatment and prevention of COVID-19 based on its anti-NLRP3 inflammasome efficacy.

Diabetes, Metformin and the Clinical Course of Covid-19: Outcomes, Mechanisms and Suggestions on the Therapeutic Use of Metformin

Objectives: Pre-existing or new diabetes confers an adverse prognosis in people with Covid-19. We reviewed the clinical literature on clinical outcomes in metformin-treated subjects presenting with Covid-19. Methods: Structured PubMed search: metformin AND [covid (ti) OR covid-19 (ti) OR covid19 (ti) OR coronavirus (ti) OR SARS-Cov2 (ti)], supplemented with another PubMed search: "diabetes AND [covid OR covid-19 OR covid19 OR coronavirus (i) OR SARS-Cov2 (ti)]" (limited to "Clinical Study", "Clinical Trial", "Controlled Clinical Trial", "Meta-Analysis", "Observational Study", "Randomized Controlled Trial", "Systematic Review"). Results: The effects of metformin on the clinical course of Covid-19 were evaluated in retrospective analyses: most noted improved clinical outcomes amongst type 2 diabetes patients treated with metformin at the time of hospitalisation with Covid-19 infection. These outcomes include reduced admission into intensive care and reduced mortality in subgroups with versus without metformin treatment. Conclusion: The pleiotropic actions of metformin associated with lower background cardiovascular risk may mediate some of these effects, for example reductions of insulin resistance, systemic inflammation and hypercoagulability. Modulation by metformin of the cell-surface ACE2 protein (a key binding target for SARS-CoV 2 spike protein) via the AMP kinase pathway may be involved. While pre-existing metformin treatment offers potentially beneficial effects and can be continued when Covid-19 infection is not severe, reports of increased acidosis and lactic acidosis in patients with more severe Covid-19 disease remind that metformin should be withdrawn in patients with hypoxaemia or acute renal disease. Prospective study of the clinical and metabolic effects of metformin in Covid-19 is warranted.

Controlling the Burden of COVID-19 by Manipulating Host Metabolism

The coronavirus disease 2019 (COVID-19) pandemic caused by the coronavirus-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to cause global health problems, but its impact would be minimized if the many effective vaccines that have been developed were available and in widespread use by all societies. This ideal situation is not occurring so other means of controlling COVID-19 are needed. In this short review, we make the case that manipulating host metabolic pathways could be a therapeutic approach worth exploring. The rationale for such an approach comes from the fact that viruses cause metabolic changes in cells they infect, effective host defense mechanisms against viruses requires the activity of one or more metabolic pathways, and that hosts with metabolic defects such as diabetes are more susceptible to severe consequences after COVID-19. We describe the types of approaches that could be used to redirect various aspects of host metabolism and the success that some of these maneuvers have had at controlling other virus infections. Manipulating metabolic activities to control the outcome of COVID-19 has to date received minimal attention. Manipulating host metabolism will never replace vaccines to control COVID-19 but could be used as an adjunct therapy to the extent of ongoing infection.

Inpatient use of metformin and acarbose is associated with reduced mortality of COVID-19 patients with type 2 diabetes mellitus

Aims

Type 2 diabetes mellitus (T2DM) is a strong risk factor for complications of coronavirus disease 2019 (COVID‐19). The effect of T2DM medications on COVID‐19 outcomes remains unclear. In a retrospective analysis of a cohort of 131 patients with T2DM hospitalized for COVID‐19 in Wuhan, we have previously found that metformin use prior to hospitalization is associated with reduced mortality. The current study aims to investigate the effects of inpatient use of T2DM medications, including metformin, acarbose, insulin and sulfonylureas, on the mortality of COVID‐19 patients with T2DM during hospitalization.

Methods

We continue to carry out a retrospective analysis of a cohort of 131 patients with T2DM hospitalized for COVID‐19 and treated with different combinations of diabetes medications.

Results

We found that patients using metformin (p = .02) and acarbose (p = .04), alone or both together (p = .03), after admission were significantly more likely to survive than those who did not use either metformin or acarbose. 37 patients continued to take metformin after admission and 35 (94.6%) survived. Among the 57 patients who used acarbose after admission, 52 survived (91.2%). A total of 20 patients used both metformin and acarbose, while 57 used neither. Of the 20 dual‐use patients, 19 (95.0%) survived.

Conclusion

Our analyses suggest that inpatient use of metformin and acarbose together or alone during hospitalization should be studied in randomized trials.

Inflammasome activation at the crux of severe COVID-19

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), results in life-threatening disease in a minority of patients, especially elderly people and those with co-morbidities such as obesity and diabetes. Severe disease is characterized by dysregulated cytokine release, pneumonia and acute lung injury, which can rapidly progress to acute respiratory distress syndrome, disseminated intravascular coagulation, multisystem failure and death. However, a mechanistic understanding of COVID-19 progression remains unclear. Here we review evidence that SARS-CoV-2 directly or indirectly activates inflammasomes, which are large multiprotein assemblies that are broadly responsive to pathogen-associated and stress-associated cellular insults, leading to secretion of the pleiotropic IL-1 family cytokines (IL-1β and IL-18), and pyroptosis, an inflammatory form of cell death. We further discuss potential mechanisms of inflammasome activation and clinical efforts currently under way to suppress inflammation to prevent or ameliorate severe COVID-19.

Mortality Risk of Antidiabetic Agents for Type 2 Diabetes With COVID-19: A Systematic Review and Meta-Analysis

Aims

We conducted a systematic review and meta-analysis to assess various antidiabetic agents' association with mortality in patients with type 2 diabetes (T2DM) who have coronavirus disease 2019 (COVID-19).

Methods

We performed comprehensive literature retrieval from the date of inception until February 2, 2021, in medical databases (PubMed, Web of Science, Embase, and Cochrane Library), regarding mortality outcomes in patients with T2DM who have COVID-19. Pooled OR and 95% CI data were used to assess relationships between antidiabetic agents and mortality.

Results

Eighteen studies with 17,338 patients were included in the meta-analysis. Metformin (pooled OR, 0.69; P=0.001) and sulfonylurea (pooled OR, 0.80; P=0.016) were associated with lower mortality risk in patients with T2DM who had COVID-19. However, patients with T2DM who had COVID-19 and received insulin exhibited greater mortality (pooled OR, 2.20; P=0.002). Mortality did not significantly differ (pooled OR, 0.72; P=0.057) between DPP-4 inhibitor users and non-users.

Conclusions

Metformin and sulfonylurea could be associated with reduced mortality risk in patients with T2DM who have COVID-19. Furthermore, insulin use could be associated with greater mortality, while DPP-4 inhibitor use could not be. The effects of antidiabetic agents in patients with T2DM who have COVID-19 require further exploration.

Systematic Review Registration

PROSPERO (identifier, CRD42021242898).

Metformin in Patients With COVID-19: A Systematic Review and Meta-Analysis

Importance/Background: The coronavirus disease (COVID-19) pandemic is a critical public health issue. Evidence has shown that metformin favorably influences COVID-19 outcomes. This study aimed to assess the benefits and risks of metformin in COVID-19 patients. Methods: We searched the PubMed, Embase, Cochrane Library, and Chinese Biomedical Literature Database from inception to February 18, 2021. Observational studies assessing the association between metformin use and the outcomes of COVID-19 patients were included. The primary outcome was mortality, and the secondary outcomes included intubation, deterioration, and hospitalization. Random-effects weighted models were used to pool the specific effect sizes. Subgroup analyses were conducted by stratifying the meta-analysis by region, diabetic status, the adoption of multivariate model, age, risk of bias, and timing for adding metformin. Results: We identified 28 studies with 2,910,462 participants. Meta-analysis of 19 studies showed that metformin is associated with 34% lower COVID-19 mortality [odds ratio (OR), 0.66; 95% confidence interval (CI), 0.56-0.78; I 2 = 67.9%] and 27% lower hospitalization rate (pooled OR, 0.73; 95% CI, 0.53-1.00; I 2 = 16.8%). However, we did not identify any subgroup effects. The meta-analysis did not identify statistically significant association between metformin and intubation and deterioration of COVID-19 (OR, 0.94; 95% CI, 0.77-1.16; I 2 = 0.0% for intubation and OR, 2.04; 95% CI, 0.65-6.34; I 2 = 79.4% for deterioration of COVID-19), respectively. Conclusions: Metformin use among COVID-19 patients was associated with a reduced risk of mortality and hospitalization. Our findings suggest a relative benefit for metformin use in nursing home and hospitalized COVID-19 patients. However, randomized controlled trials are warranted to confirm the association between metformin use and COVID-19 outcomes. Study Registration: The study was registered on the PROSPERO on Feb 23, 2021 (CRD42021238722).

The effect of metformin on mortality and severity in COVID-19 patients with diabetes mellitus

AIM

COVID-19 has spread globally with heavy impact on most countries and our therapeutic strategies in COVID-19 patients with diabetes are still limited. Recently, some new information was added to this field. We performed this updated meta-analysis to reveal the underlying effect of metformin on COVID-19 patients with diabetes.

METHODS

We searched the PubMed, Embase and CNKI (China National Knowledge Infrastructure) databases for all articles. The odds ratio (OR) corresponding to the 95% confidence interval (95% CI) was used to assess the effect of metformin on COVID-19 patients with diabetes. The statistical heterogeneity among studies was assessed with the Q-test and I² statistics.

RESULTS

We collected 17 studies including 20,719 COVID-19 patients with diabetes. Our results found that metformin was associated with significantly decreased mortality and severity in COVID-19 patients with diabetes (OR = 0.64, 95% CI = 0.51-0.79 for mortality, and OR = 0.81, 95% CI = 0.66-0.99 for severity).

CONCLUSIONS

Our meta-analysis indicated that following metformin treatment might benefit the patients with T2DM, both the mortality and severity. However, patients with severe COVID-19 should be monitored closely for the development of lactic acidosis, acidosis, and decreased kidney function.

Is diabetes mellitus a wrongdoer to COVID-19 severity?

The coronavirus disease 19 (COVID-19) has turned out to be a pandemic in short period of time due to the high transmissibility of its causative agent, severe acute respiratory syndrome coronavirus 2. Various reports have suggested the promising link between overexpression of angiotensin converting enzyme 2 (ACE2) and COVID-19 pathogenesis. The severity of COVID-19 pathophysiology is greatly depended on several comorbidities, like hypertension, diabetes mellitus (DM), respiratory and cardiovascular disease, out of which DM has emerged as a major risk factor. The current review focuses on the link among the expression of ACE2, use of ACE inhibitors (ACEIs) and angiotensin II type 1 receptor blockers (ARBs), and risk of COVID-19 pathogenesis in DM. The review also emphasizes on synergistic detrimental effect of DM and COVID-19 on the immune system in provoking uncontrolled cytokine storm which eventually leads to lethal consequences. Finally, several possible therapeutic strategies have been highlighted to reduce the excess of risk associated with COVID-19 in people with DM.

Correlation of Hemoglobin A1C and Outcomes in Patients Hospitalized With COVID-19

Objective

Diabetes is a known risk factor for severe coronavirus disease 2019 (COVID-19). We conducted this study to determine if there is a correlation between hemoglobin A1C (HbA1C) level and poor outcomes in hospitalized patients with diabetes and COVID-19.

Methods

This is a retrospective, single-center, observational study of patients with diabetes (defined by an HbA1C level of ≥6.5% or known medical history of diabetes) who had a confirmed case of COVID-19 and required hospitalization. All patients were admitted to our institution between March 3, 2020, and May 5, 2020. HbA1C results for each patient were divided into quartiles: 5.1% to 6.7% (32-50 mmol/mol), 6.8% to 7.5% (51-58 mmol/mol), 7.6% to 8.9% (60-74 mmol/mol), and >9% (>75 mmol/mol). The primary outcome was in-hospital mortality. Secondary outcomes included admission to an intensive care unit, invasive mechanical ventilation, acute kidney injury, acute thrombosis, and length of hospital stay.

Results

A total of 506 patients were included. The number of deaths within quartiles 1 through 4 were 30 (25%), 37 (27%), 34 (27%), and 24 (19%), respectively. There was no statistical difference in the primary or secondary outcomes among the quartiles, except that acute kidney injury was less frequent in quartile 4.

Conclusion

There was no significant association between HbA1C level and adverse clinical outcomes in patients with diabetes who are hospitalized with COVID-19. HbA1C levels should not be used for risk stratification in these patients.

Metformin inhibition of mitochondrial ATP and DNA synthesis abrogates NLRP3 inflammasome activation and pulmonary inflammation

Acute respiratory distress syndrome (ARDS), an inflammatory condition with high mortality rates, is common in severe COVID-19, whose risk is reduced by metformin rather than other anti-diabetic medications. Given evidence of inflammasome assembly in post-mortem COVID-19 lungs, we asked whether and how metformin inhibits inflammasome activation and exerts its anti-inflammatory effect. We show that metformin inhibited NLRP3 inflammasome activation and interleukin (IL)-1β production in cultured and alveolar macrophages along with inflammasome-independent IL-6 secretion, thus attenuating lipopolysaccharide (LPS)- and SARS-CoV-2-induced ARDS. Metformin blocked LPS-induced ATP-dependent synthesis of the NLRP3 ligand mtDNA independently of AMP-activated protein kinase (AMPK) or NF-κB. Myeloid-specific ablation of LPS-induced cytidine monophosphate kinase 2 (CMPK2), which is rate limiting for mtDNA synthesis, reduced ARDS severity without a direct effect on IL-6. Thus, inhibition of ATP and mtDNA synthesis is sufficient for ARDS amelioration.

Inpatient Use of Metformin and Acarbose Is Associated with Reduced Mortality of COVID-19 Patients with Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a strong risk factor for complications of coronavirus disease 2019 (COVID-19). The effect of T2DM medications on COVID-19 outcomes remains unclear. In a retrospective analysis of a cohort of 131 patients with T2DM hospitalized for COVID-19 in Wuhan, we have previously found that metformin use prior to hospitalization is associated with reduced mortality. Here we continue to investigate the effects of inpatient use of T2DM medications, including metformin, acarbose, insulin, and sulfonylureas, on the mortality of COVID-19 patients with T2DM during hospitalization. We found that patients using metformin and acarbose, alone or both together, after admission were significantly more likely to survive than those who did not use either metformin or acarbose. Thus, our analyses suggest that inpatient use of metformin and acarbose together or alone during hospitalization should be studied in randomized trials.