Plasma plasminogen activator inhibitor-1 is associated with end-stage proliferative diabetic retinopathy in the Northern Chinese Han population

Scoring and validation of a simple model for predicting diabetic retinopathy in patients with type 2 diabetes based on a meta-analysis approach of 21 cohorts

AIM

To develop and validate a model for predicting diabetic retinopathy (DR) in patients with type 2 diabetes.

METHODS

All risk factors with statistical significance in the DR prediction model were scored by their weights. Model performance was evaluated by the area under the receiver operating characteristic (ROC) curve, Kaplan-Meier curve, calibration curve and decision curve analysis. The prediction model was externally validated using a validation cohort from a Chinese hospital.

RESULTS

In this meta-analysis, 21 cohorts involving 184,737 patients with type 2 diabetes were examined. Sex, smoking, diabetes mellitus (DM) duration, albuminuria, glycated haemoglobin (HbA1c), systolic blood pressure (SBP) and TG were identified to be statistically significant. Thus, they were all included in the model and scored according to their weights (maximum score: 35.0). The model was validated using an external cohort with median follow-up time of 32 months. At a critical value of 16.0, the AUC value, sensitivity and specificity of the validation cohort are 0.772 ((95% confidence interval (95%CI): 0.740-0.803), p < .01), 0.715 and 0.775, respectively. The calibration curve lied close to the ideal diagonal line. Furthermore, the decision curve analysis demonstrated that the model had notably higher net benefits. The external validation results proved the reliability of the risk prediction model.

CONCLUSIONS

The simple DR prediction model developed has good overall calibration and discrimination performance. It can be used as a simple tool to detect patients at high risk of DR.

Prevalence and associated factors of proliferative diabetic retinopathy among adult diabetic patients in Northwest Ethiopia, 2023: A cross-sectional multicenter study

BACKGROUND

Proliferative diabetic retinopathy is one of the advanced complications of diabetic retinopathy. If left untreated, almost all eyes could lose a significant portion of their vision within four months. There is limited evidence regarding the magnitude of proliferative diabetic retinopathy and associated factors in the study setting and also in Ethiopia.

PURPOSE

To determine the magnitude and associated factors of proliferative diabetic retinopathy among adult diabetic patients attending Specialized Comprehensive Hospital-Diabetic Care Clinics in Northwest Ethiopia, 2023.

METHODS

A multicenter, hospital-based, cross-sectional study was conducted on 1219 adult diabetic patients selected by systematic random sampling technique. Data were collected through an in-person interview and physical examination. The Statistical Package for Social Science Version 20 was used to analyze the data. Logistic regression methods were used to test the association between predisposing factors and proliferative diabetic retinopathy. The adjusted odds ratio with a 95% confidence interval was used to determine the strength of association.

RESULTS

The prevalence of proliferative diabetic retinopathy was 3.1% (95% CI: 2.10%-4.10%). Hypertension (AOR = 4.35 (95% CI: 1.87-10.12)), peripheral neuropathy (AOR = 3.87 (95% CI: 1.57-9.54)), nephropathy (AOR = 2.58 (95% CI: 1.13-5.87)), ≥10 years duration of diabetes mellitus (AOR = 5.30 (95% CI: 2.32-12.14)), insulin use (AOR = 3.07 (95% CI: 1.08-8.68)), and poor adherence to diabetes mellitus medications (AOR = 3.77 (95% CI: 1.64-8.64)) were confirmed to have statistically significant association with proliferative diabetic retinopathy.

CONCLUSION

The prevalence of proliferative diabetic retinopathy among adult diabetic patients in the diabetes clinic was higher than the global study. Hypertension, peripheral neuropathy, nephropathy, ≥10 year's duration of diabetic mellitus, insulin use and poor adherence to diabetes mellitus medications were among the factors significantly associated with proliferative diabetic retinopathy.

Relationship between serum and tear levels of tissue plasminogen activator and plasminogen activator inhibitor-1 in diabetic retinopathy

Background

Diabetic retinopathy (DR) is a serious complication of longstanding type 2 diabetes mellitus (T2DM), a leading cause of blindness and visual disability in the world. The aim of this study is to compare the activity of tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) in tears and serum of patients with DR and those without DR.

Method

Among the T2DM patients enrolled in this study, 26 patients had DR (n = 26) while 29 were without DR (n = 29). The blood and tear samples were obtained from all participants. The level of PAI-1 and tPA were measured in both the serum and tears. Anthropometric measurements, HbA1c, renal and lipid profile were also obtained.

Results

Patients with DR had significantly longer disease duration and higher systolic blood pressure compared to those without DR. Serum PAI-1 level was significantly higher in patients with DR compared to those without DR, 32.72 (IQR 32.52) vs 21.37 (IQR 14.93) ng/mL, respectively (p < 0.05). However, tear PAI-1 were comparable in both groups. Serum and tear tPA levels in both groups were also comparable (p > 0.05). Among patients with DR, there were no significant correlations between tear and serum of both biomarkers. Patients without DR showed a moderate positive correlation between serum and tear tPA levels with a coefficient of 0.363, albeit no statistical significance. Patients with DR demonstrated a significant positive correlation between levels of tears PAI-1 and BMI (r = 0.555, p = 0.026). In the group without DR, there was a statistically significant positive correlation between serum level of PAI-1 with urine albumin creatinine ratio (UACR) (r = 0.501, p = 0.013).

Conclusion

The present study demonstrated a significantly greater serum PAI-1 levels in patients with DR compared to those without DR. No significant correlations between tears and serum PAI-1 and tPA were observed. Thus, the role of tear biomarkers remains relevant for further investigations.

Incidence and risk factors of severe non-proliferative/proliferative diabetic retinopathy: More than a decade follow up in the Tehran Lipids and Glucose Study

AIMS/INTRODUCTION

To examine the incidence rate of severe non-proliferative and proliferative diabetic retinopathy (severe-NPDR/PDR) and determine its potential risk factors.

MATERIALS AND METHODS

The study consisted of 1,169 participants (675 women) with type 2 diabetes mellitus, aged ≥20 years. A trained interviewer collected information about the history of pan-retinal photocoagulation as a result of diabetic retinopathy. Multivariable Cox proportional hazards regression models were applied.

RESULTS

We found 187 cases (126 women) of severe-NPDR/PDR during a median follow-up period of 12.7 years; the corresponding incidence rate was 13.6 per 1,000 person-years. Being overweight (hazard ratio [HR], 95% confidence interval [CI] 0.60, 0.39-0.92) and obese (HR 0.48, 95% CI 0.27-0.83) were associated with lower risk, whereas being smoker (HR 1.75, 95% CI 1.12-2.74), having fasting plasma glucose levels 7.22-10.0 mmol/L (HR 2.81, 95% CI 1.70-4.62), fasting plasma glucose ≥10 mmol/L (HR 5.87, 95% CI 3.67-9.41), taking glucose-lowering medications (HR 2.58, 95% CI 1.87-3.56), prehypertension status (HR 1.65, 95% CI 1.05-2.58) and newly diagnosed hypertension (HR 1.96, 95% CI 1.06-3.65) increased the risk of severe-NPDR/PDR. Among newly diagnosed diabetes patients, being male was associated with a 59% lower risk of severe-NPDR/PDR (HR 0.41, 95% CI 0.21-0.79). Furthermore, patients who had an intermediate level of education (6-12 years) had a higher risk of developing PDR (HR 1.86, 95% CI 1.05-3.30) compared with those who had <6 years of education.

CONCLUSIONS

Among Iranians with type 2 diabetes mellitus, 1.36% developed severe-NPDR/PDR annually. Normal bodyweight, being a smoker, out of target fasting plasma glucose level, prehypertension and newly diagnosed hypertension status were independent risk factors of severe-NPDR/PDR. Regarding the sight-threatening entity of advanced diabetic retinopathy, the multicomponent strategy to control diabetes, abstinence of smoking and tight control of blood pressure should be considered.

Waist-Height Ratio and the Risk of Severe Diabetic Eye Disease in Type 1 Diabetes: A 15-Year Cohort Study

CONTEXT

Obesity prevalence has increased in type 1 diabetes (T1D). However, the relationship between body composition and severe diabetic eye disease (SDED) is unknown.

OBJECTIVE

To investigate the associations between body composition and SDED in adults with T1D.

METHODS

From 5401 adults with T1D in the Finnish Diabetic Nephropathy Study, we assessed 3468, and 437 underwent dual-energy X-ray absorptiometry for body composition analysis. The composite outcome was SDED, defined as proliferative retinopathy, laser treatment, antivascular endothelial growth factor treatment, diabetic maculopathy, vitreous hemorrhage, and vitrectomy. Logistic regression analysis evaluated the associations between body composition and SDED. Multivariable Cox regression analysis assessed the associations between the anthropometric measures and SDED. Subgroup analysis was performed by stages of albuminuria. The relevance ranking of each variable was based on the z statistic.

RESULTS

During a median follow-up of 14.5 (interquartile range 7.8-17.5) years, 886 SDED events occurred. Visceral/android fat ratio was associated with SDED [odds ratio (OR) 1.40, z = 3.13], as well as the percentages of visceral (OR 1.80, z = 2.45) and android fat (OR 1.28, z = 2.08) but not the total body fat percentage. Waist-height ratio (WHtR) showed the strongest association with the SDED risk [hazard ratio (HR) = 1.28, z = 3.73], followed by the waist (HR 1.01, z = 3.03), body mass index (HR 1.03, z = 2.33), and waist-hip ratio (HR 1.15, z = 2.22). The results were similar in normo- and microalbuminuria but not significant in macroalbuminuria. A WHtR ≥ 0.5 increased the SDED risk by 28% at the normo- and microalbuminuria stages.

CONCLUSIONS

WHtR, a hallmark of central obesity, is associated with SDED in individuals with T1D.

PAI-1 in Diabetes: Pathophysiology and Role as a Therapeutic Target

Hypofibrinolysis is a key abnormality in diabetes and contributes to the adverse vascular outcome in this population. Plasminogen activator inhibitor (PAI)-1 is an important regulator of the fibrinolytic process and levels of this antifibrinolytic protein are elevated in diabetes and insulin resistant states. This review describes both the physiological and pathological role of PAI-1 in health and disease, focusing on the mechanism of action as well as protein abnormalities in vascular disease with special focus on diabetes. Attempts at inhibiting protein function, using different techniques, are also discussed including direct and indirect interference with production as well as inhibition of protein function. Developing PAI-1 inhibitors represents an alternative approach to managing hypofibrinolysis by targeting the pathological abnormality rather than current practice that relies on profound inhibition of the cellular and/or acellular arms of coagulation, and which can be associated with increased bleeding events. The review offers up-to-date knowledge on the mechanisms of action of PAI-1 together with the role of altering protein function to improve hypofirbinolysis. Developing PAI-1 inhibitors may form for the basis of future new class of antithrombotic agents that reduce vascular complications in diabetes.

Indicating and predicting role of the horizontal C/D ratio in preclinical diabetic retinopathy associated with chronic angle-closure glaucoma

AIM

To observe morphological optic disc characteristics in patients with preclinical diabetic retinopathy (DR) associated with chronic angle-closure glaucoma (CACG).

METHODS

Twenty-two cases (43 eyes) of preclinical DR associated with CACG were enrolled in group A; 24 preclinical DR cases (46 eyes) were enrolled in group B; 26 CACG cases (51 eyes) were enrolled in group C; and 49 normal controls (49 eyes) were enrolled in group D. All underwent optical coherence tomography to measure the horizontal C/D ratio (HCDR), C/D area ratio (CDaR), vertical C/D ratio (VCDR), rim area (RA), cup volume (CV), disc area (DA) and average retinal nerve fiber layer (RNFL) thickness.

RESULTS

The ages of groups A, B, C, and D were 67.60±3.36, 66.78±3.33, 65.98±3.83, and 67.54±3.17y, respectively. The HCDR values in groups A, B, and C were distinct relative to those in group D (P<0.0001, P<0.01, and P<0.05, respectively). The HCDR values in group A were higher compared with those in groups B (P<0.0001) and D (P<0.0001); while these values were virtually identical statistically between groups A and C (P>0.05). The CDaR values in group A were higher in comparison to those in groups B and D (P<0.0001 in both groups); while these values were virtually identical statistically between groups A and C (P>0.05). The RA values in group A were smaller relative to those in groups B and D (P<0.0001 in both groups); while groups A and C were not distinct statistically (P>0.05). The CV values in group A were greater in comparison to those in groups B and D (P<0.0001 in both groups); while groups A and C were not distinct statistically (P>0.05). DA was not distinct for comparisons of two groups among the four groups (P>0.05). HCDR value correlated with mean nasal RNFL thickness (r=-0.909, P<0.0001), mean superior RNFL thickness (r=-0.866, P<0.0001), mean inferior RNFL thickness (r=-0.650, P<0.001) and mean temporal RNFL thickness (r=-0.562, P<0.01) in group A.

CONCLUSION

The HCDR was a sensitive morphological parameter in detecting structural visual disc changes in preclinical DR associated with CACG, which can reflect optic nerve damage caused jointly by CACG and diabetes. A higher HCDR may predict optic nerve atrophy.

The association of smoking and risk of diabetic retinopathy in patients with type 1 and type 2 diabetes: a meta-analysis

PURPOSE

To clarify the relevance between smoking and diabetic retinopathy in patients with type 1 and type 2 diabetes mellitus.

METHODS

Published evidence were searched in MEDLINE and EMBASE from the databases began until Feb. 2017. Studies evaluating the association between smoking and diabetic retinopathy or evaluating the risk factors of diabetic retinopathy including smoking were included.

RESULTS

Totally 73 studies were identified, among which 19 studies included type 1 diabetes patients and 56 studies included type 2 diabetes patients. In type 1 diabetes, compare with non-smokers, the risk of diabetic retinopathy significantly increased in smokers (risk ratio (RR) = 1.23, 95% CI 1.14, 1.33, P < 0.001), and the risk of proliferative diabetic retinopathy also significantly increased in smokers (RR = 1.48, 95% CI 1.20, 1.81, P < 0.001). In type 2 diabetes, compare with non-smokers, the risk of diabetic retinopathy significantly decreased in smokers (RR = 0.92, 95% CI 0.86, 0.98, P = 0.02) and the risk of proliferative diabetic retinopathy also significantly decreased in smokers (RR = 0.68, 95% CI 0.61, 0.74, P < 0.001).

CONCLUSIONS

Compare with non-smokers, the risk of diabetic retinopathy significantly increased in smokers with type 1 diabetes while significantly decreased in smokers with type 2 diabetes. However, this result did not change the importance of smoking cessation for public health.

Glucagon-like peptide-1 receptor agonist diminishes endothelial dysfunction in type 2 diabetic patients

Objective. To evaluate liraglutide (LIR) endothelial protective action. Material and methods. Type 2 diabetic patients with HbA1C 7.5-9.0 % had metformin (MET) dose titrated for 3 months. Patients with HbA1C less than 7.5 % comprised group 1 (MET), more than 7.5 % - group 2 (MET+LIR). Blood concentrations of tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), endothelin-1 (E) were evaluated at baseline, in 3, 6 and 9 months. Results. PAI-1 was increased in both groups and gradually decreased. T-PA was normal. E was primarily increased only in group 2. E was normal in group 1 in general, but enlarged with glycaemia increase. E decreased in group 2 with glycaemia improvement and worsening. Conclusions. Glycaemia control improvement decreases endothelial dysfunction. LIR improves vasomotor endothelial function, independently on its influence on glycaemia.

Identification of genes related to proliferative diabetic retinopathy through RWR algorithm based on protein-protein interaction network

Proliferative diabetic retinopathy (PDR) is one of the most common complications of diabetes and can lead to blindness. Proteomic studies have provided insight into the pathogenesis of PDR and a series of PDR-related genes has been identified but are far from fully characterized because the experimental methods are expensive and time consuming. In our previous study, we successfully identified 35 candidate PDR-related genes through the shortest-path algorithm. In the current study, we developed a computational method using the random walk with restart (RWR) algorithm and the protein-protein interaction (PPI) network to identify potential PDR-related genes. After some possible genes were obtained by the RWR algorithm, a three-stage filtration strategy, which includes the permutation test, interaction test and enrichment test, was applied to exclude potential false positives caused by the structure of PPI network, the poor interaction strength, and the limited similarity on gene ontology (GO) terms and biological pathways. As a result, 36 candidate genes were discovered by the method which was different from the 35 genes reported in our previous study. A literature review showed that 21 of these 36 genes are supported by previous experiments. These findings suggest the robustness and complementary effects of both our efforts using different computational methods, thus providing an alternative method to study PDR pathogenesis.

Role of altered coagulation-fibrinolytic system in the pathophysiology of diabetic retinopathy

The implications of altered coagulation-fibrinolytic system in the pathophysiology of several vascular disorders, such as stroke and myocardial infarction, have been well researched upon and established. However, its role in the progression of diabetic retinopathy has not been explored much. Since a decade, it is known that hyperglycemia is associated with a hypercoagulated state and the various impairments it causes are well acknowledged as independent risk factors for the development of cardiovascular diseases. But recent studies suggest that the hypercoagulative state and diminished fibrinolytic responses might also alter retinal homeostasis and induce several deleterious molecular changes in retinal cells which aggravate the already existing hyperglycemia-induced pathological conditions and thereby lead to the progression of diabetic retinopathy. The major mediators of coagulation-fibrinolytic system whose concentration or activity get altered during hyperglycemia include fibrinogen, antithrombin-III (AT-III), plasminogen activator inhibitor-1 (PAI-1) and von Willebrand factor (vWF). Inhibiting the pathways by which these altered mediators get involved in the pathophysiology of diabetic retinopathy can serve as potential targets for the development of an adjuvant novel alternative therapy for diabetic retinopathy.

Tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) in diabetic foot syndrome

PURPOSE

The aim was to evaluate tissue plasminogen activator (tPA) and plasminogen activator inhibitor type 1 (PAI-1) concentration using enzyme linked immunosorbent assay method (ELISA) in diabetic foot syndrome (DFS) as compared to a group of healthy people and patients with diabetes mellitus without symptomatic vascular complications (DM2T).

MATERIAL/METHODS

Venous blood samples were collected from 90 patients with type 2 diabetes mellitus (30 - DM2T; 60 - DFS). Age-matched controls were also included (n=30). tPA and PAI-1 plasma levels were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

We found a significantly lower concentration of tPA:Ag in patients with DFS in comparison to the DM2T group; tPA concentrations were significantly higher in DM2T as compared to the control group. We observed significantly lower concentration of PAI-1:Ag in DF patients treated for hypertension as compared to patients without hypertension. The tPA:Ag and PAI-1:Ag concentration analysis in DFS depending on age, gender and BMI did not show any significant differences.

CONCLUSIONS

A lower concentration of tPA in patients with DFS may be associated with damage to the endothelial cells, especially in the microvasculature, and the sympathetic nervous system.

Cellular stress and innate inflammation in organ-specific autoimmunity: lessons learned from vitiligo

For decades, research in autoimmunity has focused primarily on immune contributions to disease. Yet recent studies report elevated levels of reactive oxygen species and abnormal activation of the unfolded protein response in cells targeted by autoimmunity, implicating cellular stress originating from the target tissue as a contributing factor. A better understanding of this contribution may help to answer important lingering questions in organ-specific autoimmunity, as to what factors initiate disease and what directs its tissue specificity. Vitiligo, an autoimmune disease of the skin, has been the focus of translational research for over 30 years, and both melanocyte stress and immune mechanisms have been thought to be mutually exclusive explanations for pathogenesis. Chemical-induced vitiligo is a unique clinical presentation that reflects the importance of environmental influences on autoimmunity, provides insight into a new paradigm linking cell stress to the immune response, and serves as a template for other autoimmune diseases. In this review, I will discuss the evidence for cell stress contributions to a number of autoimmune diseases, the questions that remain, and how vitiligo, an underappreciated example of organ-specific autoimmunity, helps to answer them.

Risk factors for diabetic retinopathy in northern Chinese patients with type 2 diabetes mellitus

AIM

To investigate the prevalence and risk factors of diabetic retinopathy (DR) in northern Chinese patients with type 2 diabetes mellitus (T2DM).

METHODS

This retrospective cross-sectional study was performed between May 2011 and April 2012. A total of 1100 patients (male/female, 483/617) were included in this study. DR was defined following the Early Treatment Diabetic Retinopathy Study (ETDRS) severity scale. All included patients accepted a comprehensive ophthalmic examination including retinal photographs. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence interval (CI) after adjusting for age and gender.

RESULTS

Retinopathy was present in 307 patients with a prevalence of 27.9%. In univariate logistic analysis, presence of DR was associated with longer duration of diabetes (OR, 5.70; 95%CI, 2.91-12.56), higher concentration of fasting blood glucose (OR, 12.94; 95%CI, 2.40-67.71), higher level of glycosylated hemoglobin HbA1c (OR, 5.50; 95%CI, 3.78-11.97) and insulin treatment (OR, 6.99; 95%CI, 1.39-35.12). The lifestyle of patients with T2DM including smoking, alcohol consumption and regular exercise seemed not associated with the development of DR.

CONCLUSION

Our study suggests that fasting serum glucose concentration, HbA1c level, duration of diabetes and insulin treatment are potential risk factors for DR in northern Chinese patients with T2DM, while the lifestyle of included patients seems not associated with DR.

Plasminogen activator inhibitor-1 and type 2 diabetes: a systematic review and meta-analysis of observational studies

An emerging body of evidence has implicated plasminogen activator inhibitor-1 (PAI-1) in the development of type 2 diabetes (T2D), though findings have not always been consistent. We systematically reviewed epidemiological studies examining the association of PAI-1 with T2D. EMBASE, PubMed, Web of Science, and the Cochrane Library were searched to identify studies for inclusion. Fifty-two studies (44 cross-sectional with 47 unique analytical comparisons and 8 prospective) were included. In pooled random-effects analyses of prospective studies, a comparison of the top third vs. bottom third of baseline PAI-1 values generated a RR of T2D of 1.67 (95% CI 1.28–2.18) with moderate heterogeneity (I² = 38%). Additionally, of 47 cross-sectional comparisons, 34(72%) reported significantly elevated PAI-1 among diabetes cases versus controls, 2(4%) reported significantly elevated PAI-1 among controls, and 11(24%) reported null effects. Results from pooled analyses of prospective studies did not differ substantially by study design, length of follow-up, adjustment for various putative confounding factors, or study quality, and were robust to sensitivity analyses. Findings from this systematic review of the available epidemiological literature support a link between PAI-1 and T2D, independent of established diabetes risk factors. Given the moderate size of the association and heterogeneity across studies, future prospective studies are warranted.

The predictive role of markers of Inflammation and endothelial dysfunction on the course of diabetic retinopathy in type 1 diabetes

AIMS

This study was undertaken to determine whether levels of inflammation and endothelial dysfunction biomarkers in serum samples collected at baseline in the Diabetes Control and Complications Trial (DCCT) cohort could predict the development of retinopathy.

METHODS

Levels of clotting/fibrinolysis, inflammation and endothelial dysfunction biomarkers were measured in 1391 subjects with type 1 diabetes to determine whether their levels predicted increased risk to develop or accelerate progression of retinopathy during 16years of follow-up.

RESULTS

Using regression models adjusted for DCCT treatment group, duration of diabetes, baseline retinopathy scores, HbA1c and albumin excretion rate, the baseline levels of sE-selectin and PAI-1 (active) were significantly associated with increased risk of a 3-step progression in retinopathy score in the primary prevention cohort (PPC). After adjusting for additional covariates (e.g., ACE/ARB and statin therapy), this association persisted. Levels of active and total PAI-1 in the same group were also significantly associated, after similar adjustments, with the time to progress to severe non-proliferative retinopathy during the follow-up period (54 and 29%, respectively of increased risk). No associations were observed in the secondary intervention cohort for any of the outcomes.

CONCLUSIONS

High levels of sE-selectin and PAI-1 are associated with the development of retinopathy in patients with uncomplicated type 1 diabetes.

Mulberry fruit extract protects pancreatic β-cells against hydrogen peroxide-induced apoptosis via antioxidative activity

Among the many environmental stresses, excessive production of reactive oxygen species (ROS) and the ensuring oxidative stress are known to cause significant cellular damage. This has clinical implications in the onset of type 1 diabetes, which is triggered by the destruction of pancreatic β-cells and is associated with oxidative stress. In this study, we investigated the protective and antioxidative effects of mulberry extract (ME) in insulin-producing pancreatic β-cells. We found that ME protects pancreatic β-cells against hydrogen peroxide (H₂O₂)-induced oxidative stress and the associated apoptotic cell death. ME treatment significantly reduced the levels of H₂O₂-induced 2-diphenyl-1-picrylhydrazyl (DPPH) radicals, and lipid peroxidation and intracellular ROS accumulation. In addition, ME inhibited DNA condensation and/or fragmentation induced by H₂O₂. These results suggest that ME protects pancreatic β-cells against hydrogen peroxide-induced oxidative stress.