Diabetes: Chronic Metformin Treatment and Outcome Following Acute Stroke

Repurposing Antidiabetic Drugs for Cerebrovascular Diseases: Causal Evidence from Drug Target Mendelian Randomization and Colocalization

Cerebrovascular diseases have caused substantial social and economic burdens, and new treatment methods are urgently needed. Evaluating the feasibility of the use of antidiabetic drugs for treating cerebrovascular diseases is meaningful in this field. We designed a comprehensive study process that includes two-sample Mendelian randomization (MR), which uses genetic proxies for antidiabetic drug targets, summary-based MR (SMR) for mRNAs, and colocalization for drug target genes to assess their causal relationships with 10 cerebrovascular disease phenotypes. Seven of the eight main types of clinical antidiabetic drugs were identified, yielding eleven potential drug targets. Our study observed that sulfonylureas (KCNJ11) and metformin (GPD1) reduce the risk of stroke and that TZDs (PPARG) reduce the risk of hippocampal perivascular spaces. In addition, sulfonylureas can reduce the risk of certain cerebral small vessel disease. These results show that antidiabetic drugs have hypoglycemic properties and affect cerebrovascular health. Our study supports repurposing antidiabetic drugs as disease-modifying therapies to improve cerebrovascular health. Future research should focus on studying the role of drugs in different phenotypes of cerebrovascular diseases and explore the potential molecular mechanisms to analyze further the potential effects of antidiabetic drugs on cerebrovascular diseases.

Neuroprotective Effects of Metformin in Stroke Patients: A Systematic Review and Meta-analysis of Cohort Studies

OBJECTIVES

People with diabetes are 1.5 times more likely to experience stroke than those without diabetes, underlining the urgent need to address this issue. Metformin is often the initial medication chosen to manage diabetes mellitus (DM). The purpose of our systematic review and meta-analysis is to explore the potential neuroprotective effects of metformin in individuals who have received it prior to stroke.

METHOD

Our study encompassed cohort studies that drew a comparison between the severity and diverse outcomes of stroke among individuals with DM who were administered metformin prior to the stroke event and those with DM who did not receive the treatment.

RESULTS

Ten studies met the eligibility criteria. Prestroke metformin use was associated with a significantly lower National Institutes of Health Stroke Scale score (mean difference = -1.29, 95% confidence interval: -2.11 to -0.47) in ischemic stroke. Metformin pretreatment in ischemic stroke was associated with increased odds of favorable outcome (mRS < 2) at 90 days (odds ratio [OR] = 1.45, 95% confidence interval [CI]: 1.06 to 1.99), but it was not significant at discharge. Metformin was found to be associated with reduced mortality (OR = 0.52, 95% CI: 0.42 to 0.64) in ischemic stroke. In hemorrhagic stroke, the results showed a significantly lower intracranial hemorrhage volume in prestroke metformin use (mean difference = -4.77, 95% CI: -6.56 to -2.98).

CONCLUSIONS

We found that prestroke metformin use in diabetic patients yielded neuroprotective effects. In ischemic strokes, metformin reduces stroke severity and 90-day mortality; it also improves 90-day functional outcomes. In hemorrhagic strokes, prestroke metformin use can also cause less intracranial hemorrhage volume. Further clinical trials are needed to confirm its efficacy and verify its benefits in stroke management.

Repurposing metformin: A potential off-label indication for ischaemic stroke?

The term 'clinical cemetery' is frequently used to characterize ischaemic stroke, one of the leading causes of mortality and long-term morbidity globally. Over the past two decades, a number of novel therapies have been investigated for ischaemic stroke. However, aside from mechanical thrombectomy, the only FDA-approved prescription for treating ischaemic stroke is tissue plasminogen activator, which has a limited therapeutic period. Although post-stroke rehabilitation therapies are helpful in improving functional recovery, their benefits cannot be yielded promptly. Nowadays, drug repurposing might be an appealing approach to expanding therapeutic options for ischaemic stroke. During the last decade, metformin has been extensively researched as a potential repurposing medicine for ischaemic stroke, with a focus on both preventive and therapeutic approaches. With regard to the idea of repurposing metformin in ischaemic stroke, this review aims to compile the available data from pre-clinical and clinical trials, address and clarify any discrepancies, and offer solutions.

Metformin's Effects on Cognitive Function from a Biovariance Perspective: A Narrative Review

This study examines the effects of metformin on brain functions focusing on the variability of the results reported in the literature. While some studies suggest that metformin may have neuroprotective effects in diabetic patients, others report an insignificant impact of metformin on cognitive function, or even a negative effect. We propose that this inconsistency may be due to intrinsic cellular-level variability among individuals, which we term "biovariance". Biovariance persists even in demographically homogeneous samples due to complex and stochastic biological processes. Additionally, the complex metabolic actions of metformin, including its influence on neuroenergetics and neuronal survival, may produce different effects depending on individual metabolic characteristics.

Impact of Prior Metformin Use on Stroke Outcomes: A Systematic Review and Updated Meta-Analysis

Background

Metformin is a commonly prescribed oral hypoglycemic agent for diabetic patients. Its effect in reducing the incidence of stroke has already been proven. We aimed to explore the impact of prior metformin use on stroke outcomes.

Methods

The Web of Science, PubMed, Embase, and Cochrane Library were searched to identify relevant studies involving stroke patients with a history of metformin use and comparing them to non-metformin users. We analyzed the following outcomes: modified Rankin Scale (mRS), National Institutes of Health Stroke Scale (NIHSS), mortality, or length of hospitalization.

Results

Eleven studies, with 13,825 participants, were included. The metformin group showed higher favorable mRS 0 - 2 than the non-metformin group (risk ratio (RR) = 1.14, 95% confidence interval (CI): 1.09 - 1.19, P value < 0.01). Also, significantly lower mortality rates were seen in the metformin group (RR = 0.54, 95% CI: 0.46 - 0.63, P value ≤ 0.01). NIHSS at discharge was lower in the metformin group than the non-metformin group (mean difference (MD) = -0.46, 95% CI: -0.82 - -0.11, P value < 0.01). The mRS 3 - 6 indicates less favorable outcomes were higher in the non-metformin group (RR = 0.85, 95% CI: 0.77 - 0.93). At the same time, NIHSS at admission showed no statistically significant difference between the two groups. These results indicate that metformin has a beneficial impact on the severity of stroke.

Conclusions

Pre-stroke metformin therapy is associated with better post-stroke clinical outcomes and lower mortality rates. These results highlight the potential neuroprotective role of metformin and emphasize its role as an adjunctive treatment in stroke management. Further research is required to understand its mechanism better.

Effect of metformin on the clinical outcomes of stroke in patients with diabetes: a systematic review and meta-analysis

OBJECTIVES

Stroke is a major cause of death and disability globally, especially among diabetic patients. In this study, we aim to scrutinise the effects of metformin on the clinical outcomes of stroke in diabetic patients.

DESIGN

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

DATA SOURCES

PubMed, Embase and Web of Science databases were searched between their inception and 5 December 2023.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies investigating the effect of metformin on the clinical outcomes of stroke in patients with diabetes were included.

DATA EXTRACTION AND SYNTHESIS

The effect of metformin on the clinical outcomes of stroke in patients with diabetes was identified using combined ORs and 95% CIs.

RESULTS

A total of 11 studies involving 18 525 participants were included in this review. Pooled analysis has demonstrated that prestroke metformin use could reduce the probability of poor course after stroke by 34% in diabetes mellitus (DM) patients (OR=0.66, 95% CI: 0.61 to 0.72) and reduce the probability of death by 43% (OR=0.57, 95% CI: 0.51 to 0.64).

CONCLUSIONS

Prestroke metformin use is beneficial for the improvement of clinical outcomes in patients who had a stroke with DM, although the potential bias should be carefully considered.

PROSPERO REGISTRATION NUMBER

CRD42024496056.

Undiagnosed major risk factors in acute ischaemic stroke patients in Qatar: analysis from the Qatar stroke registry

Objective

We examined the presentation to hospital, subtypes of ischaemic stroke for patients admitted to stroke services in Qatar and their 90-day prognosis based on the modified Rankin Scale (mRS) for those with diagnosed and undiagnosed diabetes, hypertension and dyslipidaemia.

Methods

We conducted a retrospective analysis of patients admitted with acute ischaemic stroke from January 2014 to April 2024. The mRS was dichotomised with favourable outcome (0-2) and unfavourable outcome (3-6).

Results

A total of 9479 patients were included in the study. Patients with a prior history of hypertension and dyslipidaemia and untreated/undiagnosed for these risk factors on admission were more likely to present with a lower National Institute of Health Stroke Scale (NIHSS) score at admission (p<0.001). These patients were also more likely to present with small vessel disease (SVD) or subcortical stroke (p<0.001). Multivariate analysis revealed that age (adjusted OR 1.05, 95% CI 1.04 to 1.06) and hypertension (adjusted OR 1.44, 95% CI 1.07 to 1.96) were more likely to have an mRS score of 3-6 at 90 days while males (adjusted OR 0.56, 95% CI 0.46 to 0.69), prior antidiabetic therapy (adjusted OR 0.52, 95% CI 0.34 to 0.79) and undiagnosed diabetes (adjusted OR 0.46, 95% CI 0.22 to 0.99) were protective against an mRS score of 3-6 at 90 days after adjusting for covariates.

Conclusion

Patients with a prior history of hypertension and dyslipidaemia and undiagnosed on admission are more likely to present with a lower NIHSS score but have a worse outcome at 90 days. The lower NIHSS may be explained by a higher frequency of SVD.

Neuroprotective Effects of Metformin on Cerebral Ischemia-Reperfusion Injury: Modulation of JNK and p38 MAP Kinase Signaling Pathways

Cerebral ischemia-reperfusion injury (CIRI) is a significant pathological process in stroke, characterized by neuronal cell death and neurological dysfunction. Metformin, commonly used for diabetes management, has been noted for its neuroprotective properties, though its effects on CIRI and the mechanisms involved remain unclear. This study explored the neuroprotective impact of metformin on CIRI, focusing on its potential to modulate the c-Jun N-terminal kinase (JNK) and p38 MAP kinase (p38) signaling pathways. Using in vitro models of oxygen-glucose deprivation/reperfusion (OGD/R) in neuronal cells and in vivo mouse models of middle cerebral artery occlusion (MCAO), the effects of metformin were assessed. Cell viability was measured with Cell Counting Kit-8 (CCK-8), protein expression via Western Blot (WB), and apoptosis through flow cytometry. The extent of brain injury in mice was evaluated using 2,3,5-triphenyltetrazolium chloride (TTC) staining, while JNK and p38 activation statuses were detected through WB and phospho-JNK (p-JNK) immunofluorescence staining. Results showed that metformin significantly improved the viability of HT22 cells post-OGD/R, reduced apoptosis, and decreased OGD/R-induced phosphorylation of JNK and p38 in vitro. In vivo, metformin treatment notably reduced brain infarct volume in MCAO mice, inhibited p-p38 and p-JNK expression, and enhanced neurological function. These findings suggest that metformin exerts neuroprotective effects against CIRI by modulating the JNK/p38 signaling pathway, highlighting its potential therapeutic value in treating cerebral ischemia-reperfusion injury and paving the way for clinical applications.

Effectiveness of metformin pretreatment for stroke severity: A propensity score matching study

BACKGROUND AND OBJECTIVE

Metformin pretreatment might have neuroprotective effects. We aimed to determine the therapeutic effects of the antidiabetic medication metformin on ischemic stroke severity and discharge outcomes.

METHODS

We analyzed data on 1303 ischemic stroke patients who were on antidiabetic medications from the Massachusetts General Hospital (MGH) Advanced Comprehensive Stroke Center dataset (n = 8943, 2012-2022). We applied propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) analyses to investigate the effect of current usage of metformin (versus alternate antidiabetic treatment) on acute stroke clinical severity and discharge outcomes.

RESULTS

Of the 1303 patients who were on antidiabetic medications at the time of stroke admission, 730 (56%) were taking metformin. Metformin users were younger and more frequently had hypertension, whereas less frequently had prior CAD, AFib, and chronic kidney disease. The clinical features and laboratory values of the two groups were evenly distributed after PSM. Metformin-treated patients had statistically significant lower stroke severity on admission [National Institutes of Health Stroke Scale (NIHSS) (median, interquartile range) 3.0 (1.0-8.0) vs. 4.0 (2.0-11.3), p = 0.011], better functional independence at discharge (modified Rankin scale score 0-2, 36.3% vs. 25.4%, p < 0.001) and less in-hospital mortality (4.5% vs. 11.3%, p = 0.018). IPTW analysis results were consistent with PSM results.

CONCLUSIONS

Among diabetic patients with acute ischemic stroke, metformin appears to confer neuroprotection. Our results extend previous findings to the general stroke population. Stroke patients with diabetes mellitus who were treated with metformin prior to stroke, even when combined with additional antidiabetic medications, experienced less severe strokes upon admission and had better functional outcomes during hospitalization.

Diabetes and Stroke—A Focused Review

Globally, diabetes mellitus (DM) and stroke are two common chronic illnesses that have a substantial impact on rates of morbidity and mortality. There is significant evidence linking diabetes to an increased risk of stroke in terms of incidence, severity, and mortality. This extensive review looks at shared risk factors, underlying pathophysiological mechanisms, epidemiological trends, and evidence-based therapy approaches to give a thorough analysis of the causal relationship between diabetes mellitus and stroke. Studies using epidemiological data regularly show that people with diabetes have a higher incidence of stroke than people without the disease. Furthermore, diabetes is linked to a less favorable outcome following a stroke, as well as an elevated chance of stroke recurrence. Determining the pathophysiological pathways that connect diabetes and stroke is essential to understanding their relationship. Key pathophysiological processes associated with these disorders include endothelial dysfunction, inflammation, oxidative stress, hyperglycemia, and dyslipidemia. Due to microvascular complications, these mechanisms raise the risk of hemorrhagic stroke and predispose diabetics to an increased risk of ischemic stroke by creating a prothrombotic and atherosclerotic milieu. Diabetes and stroke are linked due to shared risk factors like smoking, obesity, dyslipidemia, hypertension, and poor glycemic control. Lifestyle changes, blood pressure control, lipid-lowering therapy, antiplatelet medicines, and a nutritious diet are essential for stroke risk reduction. Reducing the risk of stroke in people with diabetes requires the implementation of management techniques that focus on both diabetes control and stroke prevention. Optimizing results and lowering the frequency of stroke-related complications in diabetics requires multidisciplinary care. The intricate interactions between diabetes mellitus and stroke are highlighted in this review’s conclusion, which also highlights the value of patient education, risk factor treatment, the effect of antidiabetic therapy on stroke, and integrated care in lowering the incidence of stroke in people with diabetes.

The impact of pre-stroke metformin use on clinical outcomes after acute ischemic stroke: A systematic review and meta-analysis

OBJECTIVES

Stroke is a leading cause of mortality and disability globally, with limited treatment options available for acute ischemic stroke (AIS) patients. Type 2 diabetes mellitus (T2DM) is not only widespread but also a known risk factor for stroke. Our meta-analysis aims to assess the influence of pre-stroke metformin use on the clinical outcomes in AIS patients with T2DM.

MATERIALS AND METHODS

We conducted this study following PRISMA guidelines, searching the following databases: Medline, Embase, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials up to February 29, 2024. All studies providing separate data on AIS patients using metformin were included, and statistical analysis was conducted using R software to pooled odds ratios (ORs) and their corresponding 95% confidence intervals (CI).

RESULTS

Out of 1051 studies, 7 met the inclusion criteria for our meta-analysis with a total of 11589 diabetic patients, including 5445 patients taking metformin and 6144 diabetic patients in the non-metformin group. Compared to the non-metformin group, the metformin group had a significantly higher rate of mRS 0-2 score at discharge (OR 1.56; 95% CI 1.25:1.95; p=< 0.01) and a lower rate of 90-day mortality (OR 0.51; 95% CI 0.42:0.61; p=< 0.01), with no significant difference in sICH (OR 0.88; 95% CI 0.47:1.64; p= 0.68) between the two groups.

CONCLUSIONS

Our meta-analysis demonstrated that pre-stroke metformin use is associated with higher functional independence and lower mortality in AIS patients with T2DM.

Metformin alleviates cerebral ischemia/reperfusion injury aggravated by hyperglycemia via regulating AMPK/ULK1/PINK1/Parkin pathway-mediated mitophagy and apoptosis

Stroke remains the main leading cause of death and disabilities worldwide, with diabetes mellitus being a significant independent risk factor for it. Metformin, as an efficient hypoglycemic drug in treating type 2 diabetes, has been reported to alleviate the risk of diabetes-related stroke. However, its underlying mechanisms remain unclear. This study aimed to investigate the role of mitophagy and its regulatory pathway in the neuroprotective mechanism of metformin against cerebral ischemia/reperfusion (I/R) injury aggravated by hyperglycemia. A hyperglycemic cerebral I/R animal model and a high glucose cultured oxygen-glucose deprivation/reperfusion (OGD/R) cell model were used in the experiment. The indexes of brain injury, cell activity, mitochondrial morphology and function, mitophagy, mitochondrial pathway apoptosis and the AMPK pathway were observed. In diabetic rats, metformin treatment decreased cerebral infarction volume and neuronal apoptosis, and improved neurological symptoms following I/R injury. Additionally, metformin induced activation of the AMPK/ULK1/PINK1/Parkin mitophagy pathway to have neuroprotective effects. In vitro, high glucose culture and OGD/R treatment impaired mitochondrial morphology and function, mitochondrial membrane potential, and induced apoptosis. However, metformin activated AMPK/ULK1/PINK1/Parkin mitophagy pathway, normalized mitochondrial injury. This protection was reversed by autophagy inhibitor 3-methyladenine (3MA) and AMPK inhibitor compound C. In conclusion, our present study validates the potential mechanism of metformin in alleviating hyperglycemia aggravated cerebral I/R injury by the activation of AMPK/ULK1/PINK1/Parkin mitophagy pathway.

Assessment of cognitive impairment and depressive signs in patients with type 2 diabetes treated with metformin from Southeast Mexico: A cross-sectional study

Multiple factors associate diabetes with cognitive impairment and depression. Antidiabetic drugs have reported antidepressant and pro-cognitive effects in diabetic and non-diabetic subjects. Antidepressant and pro-cognitive effects of metformin are reported in various studies; however, these effects are not consistent among researches. We designed a cross-sectional study. We recruited patients with T2D diagnosis from the Diabetes Clinic of the Regional Hospital of High Specialty "Dr. Gustavo A. Rovirosa Pérez" from January 2019 to May 2022. We included 431 subjects with T2D, 374 patients with metformin treatment and 57 subjects without metformin. These patients were on intensive therapies and had not a previous diagnosis of cognitive impairment or depression. We applied Mini-Mental State Examination (MMSE) to evaluate cognitive impairment, and Hamilton Depression Rating Scale (HAM-D) to assess depressive signs. Our sample had a mean age of 53.77 ± 13.43 years. Metformin users were 374 individuals, and 57 subjects didn't use metformin. MMSE found cognitive impairment in 8.3% (n = 31) of metformin users, and 14.8% (n = 8) of patients without metformin. HAM-D scale showed that 39.5% (n = 147) of patients with metformin had depression signs, subjects without metformin and depressive signs were 44.6% (n = 25). We found no differences between groups for cognitive impairment and depression grades. We did not find associations between metformin treatment, cognitive impairment measures and depression sign measures. However, chronic metformin treatment, insulin use, glycemic control and age could influence our results.

Metformin treatment and acute ischemic stroke outcomes in patients with type 2 diabetes: a retrospective cohort study

BACKGROUND AND PURPOSE

Preclinical studies have shown that metformin has neuroprotective actions in stroke. However, the optimal treatment timing and duration remain unknown. Herein, we examined the efficacy of metformin treatment on prognosis in acute ischemic stroke (AIS) patients, and assessed the optimal treatment timing and duration.

METHODS

AIS patients with type 2 diabetes mellitus were retrospectively enrolled. Patients were grouped into those who never received metformin (MET - group), those who received metformin continuously before stroke and after admission (pre-stroke + /post-stroke + group), those who only received metformin before stroke onset (pre-stroke + /post-stroke - group), and those who only received metformin after admission (pre-stroke - /post-stroke + group). The all MET + group represents the sum of the three metformin treatment groups. The efficacy outcome was the 90-day modified Rankin Scale (mRS) score.

RESULTS

In total, 309 eligible patients were included (MET - [N = 130], pre-stroke + /post-stroke + [N = 94], pre-stroke + /post-stroke - [N = 30], pre-stroke - /post-stroke + [N = 55]; all MET + [N = 179]). The all MET + group had a trend toward a lower 90-day mRS score compared with that in the MET - group (1 [0-2] vs 1 [0-3], unadjusted odds ratio [OR] = 0.652, P = 0.041; adjusted OR = 0.752, P = 0.218). In the three metformin treatment groups, only the pre-stroke + /post-stroke + group had a significantly lower 90-day mRS score (1 [0-1] vs 1 [0-3], adjusted OR = 0.497, 95%CI = 0.289-0.854; P = 0.011) and higher proportion of mRS score 0-1 (78.7% vs. 61.5%, adjusted OR = 2.278, 95%CI = 1.108-4.680; P = 0.025) than the MET - group.

CONCLUSION

AIS patients with type 2 diabetes mellitus who receive continuous metformin treatment before stroke onset and after admission have improved functional outcome at 90 days.