The Effect of Metformin Consumption on Mortality in Hospitalized COVID-19 patients: a systematic review and meta-analysis

Glucose-lowering drugs and outcome from COVID-19 among patients with type 2 diabetes mellitus: a population-wide analysis in Hong Kong

OBJECTIVES

To investigate the association between baseline use of glucose-lowering drugs and serious clinical outcome among patients with type 2 diabetes.

DESIGN

Territory-wide retrospective cohort of confirmed cases of COVID-19 between January 2020 and February 2021.

SETTING

All public health facilities in Hong Kong.

PARTICIPANTS

1220 patients with diabetes who were admitted for confirmed COVID-19.

PRIMARY AND SECONDARY OUTCOME MEASURES

Composite clinical endpoint of intensive care unit admission, requirement of invasive mechanical ventilation and/or in-hospital death.

RESULTS

In this cohort (median age 65.3 years, 54.3% men), 737 (60.4%) patients were treated with metformin, 385 (31.6%) with sulphonylureas, 199 (16.3%) with dipeptidyl peptidase-4 (DPP-4) inhibitors and 273 (22.4%) with insulin prior to admission. In multivariate Cox regression, use of metformin and DPP-4 inhibitors was associated with reduced incidence of the composite endpoint relative to non-use, with respective HRs of 0.51 (95% CI 0.34 to 0.77, p=0.001) and 0.46 (95% CI 0.29 to 0.71, p<0.001), adjusted for age, sex, diabetes duration, glycated haemoglobin (HbA1c), smoking, comorbidities and drugs. Use of sulphonylureas (HR 1.55, 95% CI 1.07 to 2.24, p=0.022) and insulin (HR 6.34, 95% CI 3.72 to 10.78, p<0.001) were both associated with increased hazards of the composite endpoint.

CONCLUSIONS

Users of metformin and DPP-4 inhibitors had fewer adverse outcomes from COVID-19 compared with non-users, whereas insulin and sulphonylurea might predict a worse prognosis.

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).

COVID-19 and Diabetes

The prevalence of diabetes in people with coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has varied worldwide. Most of the available evidence suggests a significant increase in severity and mortality of COVID-19 in people with either type 1 (T1DM) or type 2 diabetes mellitus (T2DM), especially in association with poor glycemic control. While new-onset hyperglycemia and new-onset diabetes (both T1DM and T2DM) have been increasingly recognized in the context of COVID-19 and have been associated with worse outcome, no conclusive evidence yet suggests direct tropism of SARS-CoV-2 on the β cells of pancreatic islets. While all approved oral antidiabetic agents appear to be safe in people with T2DM having COVID-19, no conclusive data are yet available to indicate a mortality benefit with any class of these drugs, in the absence of large randomized controlled trials. Expected final online publication date for the Annual Review of Medicine, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Metformin Use Is Associated with Decreased Mortality in COVID-19 Patients with Diabetes: Evidence from Retrospective Studies and Biological Mechanism

BACKGROUND AND AIMS

The coronavirus disease 2019 (COVID-19) increases hyperinflammatory state, leading to acute lung damage, hyperglycemia, vascular endothelial damage, and a higher mortality rate. Metformin is a first-line treatment for type 2 diabetes and is known to have anti-inflammatory and immunosuppressive effects. Previous studies have shown that metformin use is associated with decreased risk of mortality among patients with COVID-19; however, the results are still inconclusive. This study investigated the association between metformin and the risk of mortality among diabetes patients with COVID-19.

METHODS

Data were collected from online databases such as PubMed, EMBASE, Scopus, and Web of Science, and reference from the most relevant articles. The search and collection of relevant articles was carried out between 1 February 2020, and 20 June 2021. Two independent reviewers extracted information from selected studies. The random-effects model was used to estimate risk ratios (RRs), with a 95% confidence interval.

RESULTS

A total of 16 studies met all inclusion criteria. Diabetes patients given metformin had a significantly reduced risk of mortality (RR, 0.65; 95% CI: 0.54-0.80, p < 0.001, heterogeneity I2 = 75.88, Q = 62.20, and τ2 = 0.06, p < 0.001) compared with those who were not given metformin. Subgroup analyses showed that the beneficial effect of metformin was higher in the patients from North America (RR, 0.43; 95% CI: 0.26-0.72, p = 0.001, heterogeneity I2 = 85.57, Q = 34.65, τ2 = 0.31) than in patients from Europe (RR, 0.67; 95% CI: 0.47-0.94, p = 0.02, heterogeneity I2 = 82.69, Q = 23.11, τ2 = 0.10) and Asia (RR, 0.90; 95% CI: 0.43-1.86, p = 0.78, heterogeneity I2 = 64.12, Q = 11.15, τ2 = 0.40).

CONCLUSIONS

This meta-analysis shows evidence that supports the theory that the use of metformin is associated with a decreased risk of mortality among diabetes patients with COVID-19. Randomized control trials with a higher number of participants are warranted to assess the effectiveness of metformin for reducing the mortality of COVID-19 patients.

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.

Diabetes and COVID-19: The past, the present, and the future

Diabetes, one of the most prevalent chronic diseases in the world, is strongly associated with a poor prognosis in COVID-19. Scrupulous blood sugar management is crucial, since the worse outcomes are closely associated with higher blood sugar levels in COVID-19 infection. Although recent observational studies showed that insulin was associated with mortality, it should not deter insulin use in hospitalized patients requiring tight glucose control. Back and forth dilemma in the past with regards to continue/discontinue certain medications used in diabetes have been mostly resolved. The initial fears of consequences related to continuing certain medications have been largely dispelled. COVID-19 also necessitates the transformation in diabetes care through the integration of technologies. Recent advances in health-related technologies, notably telemedicine and remote continuous glucose monitoring, have become essential in the management of diabetes during the pandemic. Today, these technologies have changed the landscape of medicine and become more important than ever. Being a high-risk population, patients with type 1 or type 2 diabetes, should be prioritized for vaccination. In the future, as the pandemic fades, the prevalence of non-communicable diseases is expected to rise due to lifestyle changes and medical issues/dilemma encountered during the pandemic.

Paradoxical low severity of COVID-19 in Prader-Willi syndrome: data from a French survey on 647 patients

BACKGROUND

Patients with Prader-Willi syndrome (PWS) often have comorbidities, especially obesity, that may constitute a risk factor for severe forms of COVID-19. We aimed to assess prevalence and medical course of SARS-CoV-2 infection in children and adults with PWS. From November 2020 to January 2021, we performed a detailed medical survey on 342 adults and 305 children with PWS followed in the French reference center.

RESULTS

We obtained responses from 288 adults (84%) and 239 children (78%). From March 2020 to January 2021, 38 adults (13.2%) and 13 children (5.4%) with PWS had SARS-CoV-2 infection. Mean age of adults was 34.1 ± 11.9 years and mean body mass index was 40.6 ± 12.7 kg/m2; 82% had obesity and 37% had diabetes. Only 3 children (23%) had obesity and none had diabetes. Similar to the general population, the most frequent symptoms of COVID-19 were asthenia, fever, cough, headache and shortness of breath. All patients had a favorable outcome.

CONCLUSION

PWS itself is not a risk factor for severe COVID-19 in children and adults. On the contrary, evolution of SARS-CoV-2 infection in adults with PWS seems more favorable than expected, given their comorbidities.

Therapy of Type 2 Diabetes in Patients with SARS-CoV-2 Infection

COVID-19 infection poses an important clinical therapeutic problem, especially in patients with coexistent diseases such as type 2 diabetes. Potential pathogenetic links between COVID-19 and diabetes include inflammation, effects on glucose homeostasis, haemoglobin deoxygenation, altered immune status and activation of the renin-angiotensin-aldosterone system (RAAS). Moreover, drugs often used in the clinical care of diabetes (dipeptidyl peptidase 4 inhibitors, glucagon-like peptide 1 receptor agonists, sodium-glucose cotransporter 2 inhibitors, metformin and insulin) may influence the course of SARS-CoV-2 infection, so it is very important to verify their effectiveness and safety. This review summarises the new advances in diabetes therapy and COVID-19 and provides clinical recommendations that are essential for medical doctors and for patients suffering from type 2 diabetes.

Outcome and death risk of diabetes patients with Covid-19 receiving pre-hospital and in-hospital metformin therapies

BACKGROUND

COVID-19 has stroke Brazil harshly, deaths by COVID-19 in Brazil represent almost 13% of the total deaths by COVID-19 in the world, even though Brazilian population represents only 2.6% of the world population. Our aim in this study was to evaluate death and intubation outcomes and risk factors associated with COVID-19, and treatment options focusing on diabetes patients and the use of metformin pre-admission and during hospitalization.

METHODS

In this Brazilian single-center study we evaluated 1170 patients hospitalized due to COVID-19. Diabetes patients (n = 188) were divided based on their use of pre-hospital and in-hospital metformin (non-met-group and met-group).

RESULTS

In the total cohort most comorbidities were risk factors for orotracheal intubation and death. The use of chloroquine/hydroxychloroquine was significantly associated with increased death and intubation risk in uni- and multivariate analysis. Diabetes patients showed worst clinical feature compared with non-diabetes patients. In-hospital non-met-group had increased mortality (20.5%) compared to met-group (3.5%) (p = 0.0002) and univariable cox proportion hazard regression indicated in-hospital metformin reduced mortality (HR = 0.325, p = 0.035). Patients that used pre-hospital metformin showed lower severity parameters at hospital admission. (met-group: 2.45 ± 2.5; non-met-group: 4.25 ± 3.4). In all the groups older patients showed more severe clinical conditions and high risk of death and intubation.

CONCLUSION

Even though this is a single-center study, results from other reports have shown a similar trend, indicating that patients that used metformin during hospitalization have a better prognosis and reduced risk of death.

Ivermectin and mortality in patients with COVID-19: A systematic review, meta-analysis, and meta-regression of randomized controlled trials

AIMS

This systematic review and meta-analysis aims to investigate the effect of ivermectin on mortality in patients with COVID-19.

METHODS

A comprehensive systematic literature search was performed using PubMed, Scopus, Embase, and Clinicaltrials.gov from the inception of databases up until April 9, 2021. The intervention group was ivermectin and the control group was standard of care or placebo. The primary outcome was mortality reported as risk ratio (RR).

RESULTS

There were 9 RCTs comprising of 1788 patients included in this meta-analysis. Ivermectin was associated with decreased mortality (RR 0.39 [95% 0.20-0.74], p = 0.004; I2: 58.2%, p = 0.051). Subgroup analysis in patients with severe COVID-19 showed borderline statistical significance towards mortality reduction (RR 0.42 [95% 0.18-1.00], p = 0.052; I2: 68.3, p = 0.013). The benefit of ivermectin and mortality was reduced by hypertension (RR 1.08 [95% CI 1.03-1.13], p = 0.001); but was not influenced by age (p = 0.657), sex (p = 0.466), diabetes (p = 0.429). Sensitivity analysis using fixed-effect model showed that ivermectin decreased mortality in general (RR 0.43 [95% CI 0.29-0.62], p < 0.001) and severe COVID-19 subgroup (RR 0.48 [95% CI 0.32-0.72], p < 0.001).

CONCLUSIONS

Ivermectin was associated with decreased mortality in COVID-19 with a low certainty of evidence. Further adequately powered double-blinded placebo-controlled RCTs are required for definite conclusion.

Risk factors for COVID-19 hospitalisation and death in people living with diabetes: A virtual cohort study from the Western Cape Province, South Africa

BACKGROUND

COVID-19 outcomes and risk factors, including comorbidities and medication regimens, in people living with diabetes (PLWD) are poorly defined for low- and middle-income countries.

METHODS

The Provincial Health Data Centre (Western Cape, South Africa) is a health information exchange collating patient-level routine health data for approximately 4 million public sector health care seekers. Data from COVID-19 patients diagnosed between March and July 2020, including PLWD, were analysed to describe risk factors, including dispensed diabetes medications and comorbidities, and their association with COVID-19 outcomes in this population.

FINDINGS

There were 64,476 COVID-19 patients diagnosed. Of 9305 PLWD, 44.9% were hospitalised, 4.0% admitted to ICU, 0.6% received ventilation and 15.4% died. In contrast, proportions of COVID-19 patients without diabetes were: 12.2% hospitalised, 1.0% admitted, 0.1% ventilated and 4.6% died. PLWD were significantly more likely to be admitted (OR:3.73, 95 %CI: 3.53, 3.94) and to die (OR:3.01, 95 %CI: 2.76,3.28). Significant hospitalised risk factors included HIV infection, chronic kidney disease, current TB, male sex and increasing age. Significant risk factors for mortality were CKD, male sex, HIV infection, previous TB and increasing age. Pre-infection use of insulin was associated with a significant increased risk for hospitalisation (OR:1·39, 95 %CI:1·24,1·57) and mortality (OR1·49, 95 %CI:1·27; 1·74) and metformin was associated with a reduced risk for hospitalisation (OR:0·62,95 %CI:0·55, 0·71) and mortality (OR 0·77, 95 %CI:0·64; 0·92).

INTERPRETATION

Using routine health data from this large virtual cohort, we have described the association of infectious and noncommunicable comorbidities as well as pre-infection diabetes medications with COVID-19 outcomes in PLWD in the Western Cape, South Africa.

FUNDING

This research was funded in part, by the Wellcome Trust 203135/Z/16/Z, through support of NT. For the purpose of open access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript version arising from this submission. The Wellcome Centre for Infectious Diseases Research in Africa is supported by core funding from the Wellcome Trust [203135/Z/16/Z]. NT receives funding from the CIDRI-Africa Wellcome Trust grant (203135/Z/16/Z), and NT and TT receive funding from the NIH H3ABioNET award (U24HG006941). NT receives funding from the UKRI/MRC (MC_PC_MR/T037733/1).

Candesartan as a tentative treatment for COVID-19: A prospective non-randomized open-label study

BACKGROUND

This study aimed to investigate whether the addition of candesartan to the standard care regimen improved the outcome in patients with coronavirus 2019 (COVID-19).

METHODS

A prospective non-randomized open-label study was undertaken from May to August 2020 on 75 subjects (aged 18-70 years) hospitalized in Siloam Kelapa Dua Hospital. Uni- and multi-variable Cox regression analyses were performed to obtain hazard ratios (HRs). The primary outcomes were: (1) length of hospital stay; (2) time to negative swab; and (3) radiological outcome (time to improvement on chest X ray).

RESULTS

None of the 75 patients with COVID-19 required intensive care. All patients were angiotensin-receptor-blocker naïve. In comparison with the control group, the candesartan group had a significantly shorter hospital stay [adjusted HR 2.47, 95% confidence interval (CI) 1.16-5.29] after adjusting for a wide range of confounders, and no increased risk of intensive care. In the non-obese subgroup, the candesartan group had a shorter time to negative swab (unadjusted HR 2.11, 95% CI 1.02-4.36; adjusted HR 2.40, 95% CI 1.08-5.09) and shorter time to improvement in chest x ray (adjusted HR 2.82, 95% CI 1.13-7.03) compared with the control group.

CONCLUSION

Candesartan significantly reduces the length of hospital stay after adjustment for covariates. All primary outcomes improved significantly in the non-obese subgroup receiving candesartan.

Active prescription of low-dose aspirin during or prior to hospitalization and mortality in COVID-19: A systematic review and meta-analysis of adjusted effect estimates

BACKGROUND

This study aimed to investigate whether the active prescription of low-dose aspirin during or prior to hospitalization affects mortality in patients with coronavirus disease 2019 (COVID-19). Aspirin is often prescribed for secondary prevention in patients with cardiovascular disease and other comorbidities that might increase mortality, and may therefore falsely demonstrate increased mortality. To reduce bias, only studies that performed an adjusted analysis were included in this review.

METHODS

A systematic literature search of PubMed, Scopus, Embase and Clinicaltrials.gov was performed, from inception until 16 April 2021. The exposure was active prescription of low-dose aspirin during or prior to hospitalization. The primary outcome was mortality. The pooled adjusted effect estimate was reported as relative risk (RR).

RESULTS

Six eligible studies were included in this meta-analysis, comprising 13,993 patients. The studies had low-to-moderate risk of bias based on the Newcastle-Ottawa Scale. The meta-analysis indicated that the use of low-dose aspirin was independently associated with reduced mortality {RR 0.46 [95% confidence interval (CI) 0.35-0.61], P < 0.001; I2 = 36.2%}. Subgroup analysis on in-hospital low-dose aspirin administration also showed a significant reduction in mortality [RR 0.39 (95% CI 0.16-0.96), P < 0.001; I2 = 47.0%].

CONCLUSION

Use of low-dose aspirin is independently associated with reduced mortality in patients with COVID-19, with low certainty of evidence.

Diabetes and coronavirus (SARS-CoV-2): Molecular mechanism of Metformin intervention and the scientific basis of drug repurposing

Coronavirus Disease 2019 (COVID-19), caused by a new strain of coronavirus called Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), was declared a pandemic by WHO on March 11, 2020. Soon after its emergence in late December 2019, it was noticed that diabetic individuals were at an increased risk of COVID-19-associated complications, ICU admissions, and mortality. Maintaining proper blood glucose levels using insulin and/or other oral antidiabetic drugs (such as Metformin) reduced the detrimental effects of COVID-19. Interestingly, in diabetic COVID-19 patients, while insulin administration was associated with adverse outcomes, Metformin treatment was correlated with a significant reduction in disease severity and mortality rates among affected individuals. Metformin was extensively studied for its antioxidant, anti-inflammatory, immunomodulatory, and antiviral capabilities that would explain its ability to confer cardiopulmonary and vascular protection in COVID-19. Here, we describe the various possible molecular mechanisms that contribute to Metformin therapy's beneficial effects and lay out the scientific basis of repurposing Metformin for use in COVID-19 patients.

Prognostic value of fasting hyperglycemia in patients with COVID-19 - Diagnostic test accuracy meta-analysis

AIMS

This meta-analysis aimed to assess the prognostic value of fasting hyperglycemia in patients with COVID-19.

METHODS

A systematic literature search on PubMed, Embase, and Scopus were performed up until February 18, 2021. Fasting hyperglycemia was defined as fasting plasma glucose level above the reference value. The outcome of interest was poor outcome, which was a composite of mortality and severe COVID-19. The effect estimate was in odds ratio (OR).

RESULTS

There were 9045 patients from 12 studies included in this systematic review and meta-analysis. The prevalence of fasting hyperglycemia was 29%. The incidence of poor outcome was 15%. Fasting hyperglycemia was associated with poor outcome in COVID-19 (OR 4.72 [3.32, 6.72], p < 0.001; I2: 69.8%, p < 0.001). Subgroup analysis in patients without prior history of diabetes showed that fasting hyperglycemia was associated with poor outcome in COVID-19 (OR 3.387 [2.433, 4.714], p < 0.001; I2: 0, p = 0.90). Fasting hyperglycemia has a sensitivity of 0.57 [0.45, 0.68], specificity of 0.78 [0.70, 0.84], PLR of 2.6 [2.0, 3.3], NLR of 0.55 [0.44, 0.69], DOR of 5 [3, 7], and AUC of 0.74 [0.70, 0.78] for predicting poor outcome. In this pooled analysis, fasting hyperglycemia has a 32% post-test probability for poor outcome, and absence of fasting hyperglycemia confers to a 9% post-test probability. Meta-regression and subgroup analysis showed that the sensitivity and specificity varies by chronic kidney disease but not by age, male (gender), hypertension, and chronic kidney disease.

CONCLUSION

Fasting hyperglycemia was associated with mortality in COVID-19 patients, with or without diabetes.

PROSPERO

CRD42021237997.

Dipeptidyl peptidase-4 (DPP-4) inhibitor and mortality in coronavirus disease 2019 (COVID-19) - A systematic review, meta-analysis, and meta-regression

BACKGROUND AND AIMS

This study aims to synthesize evidence on dipeptidyl peptidase-4 (DPP-4) inhibitor and mortality in COVID-19 patients and factors affecting it.

METHODS

We performed a systematic literature search from PubMed, Scopus, and Embase databases from inception of databases up until 7 March 2021. Studies that met all of the following criteria were included: 1) observational studies or randomized controlled trials that report COVID-19 patients, 2) reporting DPP-4 inhibitor use, 3) mortality, and 4) mortality based on DPP-4 inhibitor use. The exposure was DPP-4 inhibitor, defined as DPP-4 inhibitor use that started prior to COVID-19 hospitalization. The control group was patients with no exposure to DPP-4 inhibitor. The outcome was mortality. The pooled effect estimate was reported as risk ratio (RR).

RESULTS

There were 4,477 patients from 9 studies in this systematic review and meta-analysis. 31% of (15%, 46%) the patients use DPP-4 inhibitor. Mortality occurs in 23% (15%, 31%) of the patients. DPP-4 inhibitor was associated with lower mortality in patients with COVID-19 (RR 0.76 [0.60, 0.97], p = 0.030, I2: 44.5%, p = 0.072). Meta-regression analysis showed that the association between DPP-4 inhibitor and mortality was significantly affected by metformin (RR 1.02 [1.00, 1.04], p = 0.048) and angiotensin converting enzyme inhibitor or angiotensin receptor blocker (ACEI/ARB) use (RR 1.04 [1.01, 1.07], p = 0.006), but not age (p = 0.759), sex (reference: male, p = 0.148), and hypertension (p = 0.218).

CONCLUSION

DPP-4 inhibitor use was associated with lower mortality in COVID-19 patients, and the association was weaker in patients who were also taking metformin and/or ACE inhibitors.

Therapeutic Potential of Metformin in COVID-19: Reasoning for Its Protective Role

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections present with increased disease severity and poor clinical outcomes in diabetic patients compared with their nondiabetic counterparts. Diabetes/hyperglycemia-triggered endothelial dysfunction and hyperactive inflammatory and immune responses are correlated to twofold to threefold higher intensive care hospitalizations and more than twice the mortality among diabetic coronavirus disease 2019 (COVID-19) patients. While comorbidities such as obesity, cardiovascular disease, and hypertension worsen the prognosis of diabetic COVID-19 patients, COVID-19 infections are also associated with new-onset diabetes, severe metabolic complications, and increased thrombotic events in the backdrop of aberrant endothelial function. While several antidiabetic medications are used to manage blood glucose levels, we discuss the multifaceted ability of metformin to control blood glucose levels and possibly attenuate endothelial dysfunction, inhibit viral entry and infection, and modify inflammatory and immune responses during SARS-CoV-2 infections. These actions make metformin a viable candidate drug to be considered for repurposing and gaining ground against the SARS-CoV-2-induced tsunami in diabetic COVID-19 patients.

Mechanisms and Potential Roles of Glucose-Lowering Agents in COVID-19: A Review

OBJECTIVE

To explore mechanistic benefits of glucose-lowering agents that extend beyond glycemic control with the potential to mitigate coronavirus disease 2019 (COVID-19) complications.

DATA SOURCES

The following PubMed literature search terms were used from July 2020 to January 2, 2021: diabetes, COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), glucose-lowering agents, and pharmacology.

STUDY SELECTION AND DATA EXTRACTION

English-language studies reporting on the association between diabetes, COVID-19 adverse outcomes, and the potential roles of glucose-lowering agents were reviewed.

DATA SYNTHESIS

Selected glucose-lowering agents have benefits beyond glycemic control, with the potential to reduce the risks of severe complications during SARS-CoV-2 infection. Key benefits include anti-inflammatory, anticoagulant, immune modulating, and enzyme/receptor effects.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review summarizes the current knowledge of glucose-lowering agents and their potential roles in COVID-19 outcomes. Considering beneficial mechanisms on COVID-19 outcomes that extend beyond glycemic control as well as safety profiles, current data suggest that dipeptidyl peptidase-IV (DPP-IV) inhibitors and metformin may have the most promise and warrant further investigation.

CONCLUSIONS

Certain glucose-lowering agents may offer additional benefits beyond glucose control-namely, by modulating the mechanisms contributing to adverse outcomes related to COVID-19 in patients with diabetes. DPP-IV inhibitors and metformin appear to have the most promise. However, current published literature on diabetes medications and COVID-19 should be interpreted with caution. Most published studies are retrospective and consist of convenience samples, and some lack adequate analytical approaches with confounding biases. Ongoing trials aim to evaluate the effects of glucose-lowering agents in reducing the severity of COVID-19 outcomes.

Multifaceted Mechanisms of Action of Metformin Which Have Been Unraveled One after Another in the Long History

While there are various kinds of drugs for type 2 diabetes mellitus at present, in this review article, we focus on metformin which is an insulin sensitizer and is often used as a first-choice drug worldwide. Metformin mainly activates adenosine monophosphate-activated protein kinase (AMPK) in the liver which leads to suppression of fatty acid synthesis and gluconeogenesis. Metformin activates AMPK in skeletal muscle as well, which increases translocation of glucose transporter 4 to the cell membrane and thereby increases glucose uptake. Further, metformin suppresses glucagon signaling in the liver by suppressing adenylate cyclase which leads to suppression of gluconeogenesis. In addition, metformin reduces autophagy failure observed in pancreatic β-cells under diabetic conditions. Furthermore, it is known that metformin alters the gut microbiome and facilitates the transport of glucose from the circulation into excrement. It is also known that metformin reduces food intake and lowers body weight by increasing circulating levels of the peptide hormone growth/differentiation factor 15 (GDF15). Furthermore, much attention has been drawn to the fact that the frequency of various cancers is lower in subjects taking metformin. Metformin suppresses the mechanistic target of rapamycin (mTOR) by activating AMPK in pre-neoplastic cells, which leads to suppression of cell growth and an increase in apoptosis in pre-neoplastic cells. It has been shown recently that metformin consumption potentially influences the mortality in patients with type 2 diabetes mellitus and coronavirus infectious disease (COVID-19). Taken together, metformin is an old drug, but multifaceted mechanisms of action of metformin have been unraveled one after another in its long history.

Metformin and Covid-19: Focused Review of Mechanisms and Current Literature Suggesting Benefit

Metformin is the first-line medication for type 2 diabetes, but it also has a long history of improved outcomes in infectious diseases, such as influenza, hepatitis C, and in-vitro assays of zika. In the current Covid-19 pandemic, which has rapidly spread throughout the world, 4 observational studies have been published showing reduced mortality among individuals with home metformin use. There are several potential overlapping mechanisms by which metformin may reduce mortality from Covid-19. Metformin's past anti-infectious benefits have been both against the infectious agent directly, as well as by improving the underlying health of the human host. It is unknown if the lower mortality suggested by observational studies in patients infected with Covid-19 who are on home metformin is due to direct activity against the virus itself, improved host substrate, or both.

Non-insulin anti-diabetic agents in patients with type 2 diabetes and COVID-19: A Critical Appraisal of Literature

BACKGROUND & AIMS

Several observational studies have recently reported the outcomes of non-insulin anti-diabetic agents (ADA) in patients with T2DM and coronavirus disease 2019 (COVID-19). We sought to review the literature to appraise the clinicians on these outcomes.

METHODS

A literature search using the specific keywords was carried out in the database of PubMed, MedRxiv and Google Scholar up till December 11, 2020 applying Boolean method. Full text of all the relevant articles that reported the outcomes of ADA in patients with T2DM and COVID-19 were retrieved. Subsequently, an appraisal of literature report was narratively presented.

RESULTS

Available studies that reported the outcomes of ADA are either case series or retrospective cohorts or prospective observational studies, in absence of the randomized controlled trials (RCTs). Results from these observational studies suggest that amongst all the non-insulin ADA, metformin users prior to the hospitalization had improved outcomes compared to the non-users. Data for dipeptidyl-peptidase-4 inhibitors (DPP-4i) are encouraging although inconsistent. No documentation of any harm or benefit has been observed for sulfonylureas (SUs), sodium glucose co-transporter-2 inhibitors (SGLT-2i) and glucagon-like peptide receptor agonists (GLP-1RAs). No data is yet available for pioglitazone.

CONCLUSION

Metformin and DPP-4i should be continued in patients with T2DM until hospitalization or unless contraindicated. No evidence of harm suggests that SUs, SGLT-2i or GLP-1RAs may not be stopped unless very sick, hospitalized or contraindicated. The results from RCTs are needed to claim any meaningful benefit with either metformin or DPP-4i in patients with T2DM and COVID-19.