Type 2 diabetes mellitus and myocardial ischemic preconditioning in symptomatic coronary artery disease patients

Role of Erythropoiesis-Stimulating Agents in Cardiovascular Protection in CKD Patients: Reappraisal of Their Impact and Mechanisms

Erythropoiesis-stimulating agents (ESAs) have markedly reduced the need for blood transfusion for renal anemia and are included in standard therapies for patients with chronic kidney disease (CKD). Various protective effects of ESAs on the cardiovascular system have been discovered through basic research, and the effects have received much attention because the rates of cardiovascular events and mortality are high in CKD patients. However, randomized clinical trials did not provide strong evidence that ESAs exert cardioprotection in humans, including CKD patients. It is difficult to assess the cardioprotective effects of ESAs in CKD patients through the clinical data that has been reported to date because the relationship between hemoglobin level rather than ESA dose and cardiovascular event rates was examined in most studies. Interestingly, recent studies using a rat model of CKD showed that the infarct size-limiting effect of an ESA was lost when its dose was increased to a level that normalized blood hemoglobin levels, suggesting that the optimal dose of an ESA for myocardial protection is less than the dose required to normalize hemoglobin levels. Furthermore, animal models of traditional coronary risk factors or comorbidities were resistant to the cardioprotective effects of ESAs because of interruptions in signal-mediated mechanisms downstream of erythropoietin receptors. In this review, we briefly discuss basic and clinical data on the impact of anemia on coronary and systemic circulation, the effects of CKD on the cardiovascular system, and the multiple pharmacological actions of ESAs to examine whether the ESAs that are prescribed for renal anemia exert any cardioprotection in patients with CKD.

Abnormal glucose regulation in Chinese patients with coronary artery disease: a gender analysis

BACKGROUND

Diabetes and impaired glucose regulation are very common in patients with coronary artery disease (CAD). In this study, we aim to investigate the prevalence of abnormal glucose regulation in men and women in Chinese CAD patients.

METHODS

In this retrospective study, 4100 patients (male, n = 2873; female, n = 1227)with CAD were enrolled. The mean age of these patients was 63 years. The demographic data, medical history, echocardiography findings and blood investigations were collected and analyzed.

RESULTS

In this population, 953 (24%) patients had definite diagnosis of type 2 diabetes mellitus, including 636 males (23%) and 317 females (27%). There was a higher prevalence of diabetes in females than men (p < 0.05). For the remaining patients, 48% (n = 959) undergone an oral glucose tolerance test (OGTT), which revealed that 83 male patients (12%) and 41 female patients (16%) suffered from the type 2 diabetes (p > 0.05). 283 men (40%) and 105 women (41%) had impaired glucose regulation (IGR) (p > 0.05). Only 338 men (25%) and 109 women (19%) showed the normal glucose regulation, implying a higher prevalence of abnormal glucose regulation in females (p < 0.01). The odd ratio (OR) showed that women were more prone to have diabetes mellitus or IGT than men and the OR was 1.44 and 1.43 respectively.

CONCLUSION

Abnormal glucose regulation is highly prevalent in CAD patients. The women are more prone to have diabetes mellitus or IGT than men.

Effects of Physical Prehabilitation on the Dynamics of the Markers of Endothelial Function in Patients Undergoing Elective Coronary Bypass Surgery

Our aim in this study was to evaluate the effect of physical training performed before CABG on the perioperative dynamics of the serum levels of asymmetric dimethylarginine (ADMA) and endothelin-1 (ET-1) of patients with stable coronary heart disease (CHD). Patients in the preoperative period were randomized into two groups: the training group (n = 43) underwent high-intensity treadmill training; the patients in the control group (n = 35) received no training before the procedure. The serum concentrations of ADMA and ET-1 were determined in the perioperative period, and the course of the early postoperative period was analyzed. In the training group, we found a significantly lower incidence of postoperative complications during hospital stays (p = 0.013). At the end of the training program, the ADMA levels were 1.8 times higher in the controls than in the training group (p = 0.001). We found that type 2 diabetes increased the probability of complications by 12 times (OR: 12.3; 95% CI: 1.24–121.5; p = 0.03), as well as elevating the concentration of ET-1 on the eve of surgery (OR: 10.7; 95% CI: 1.4–81.3; p = 0.02). Physical prehabilitation reduced the likelihood of complications nine times (OR: 0.11; 95% CI: 0.02–0.83; p = 0.03). The AUC was 0.851 ± 0.07 (95% CI: 0.71–0.98). The obtained results indicate the benefit of physical training during the prehabilitation stage since it can help to preserve endothelial function.

Influence of Hyperglycemia During Different Phases of Ischemic Preconditioning on Cardioprotection-A Focus on Apoptosis and Aggregation of Granulocytes

BACKGROUND

Ischemic preconditioning (IPC) protects the myocardium against ischemia/reperfusion injury. Evidence suggests that hyperglycemia inhibits IPC-induced cardioprotection. The effects of hyperglycemia initiated during different phases of IPC on myocardial injury were characterized with emphasis on apoptosis and aggregation of polymorphonuclear granulocytes (PMN).

METHODS

Male Wistar rats were subjected to 35 min of myocardial ischemia and 2 h of reperfusion. Control animals were not further treated. IPC was induced by three cycles of 3 min ischemia and 5 min of reperfusion before major ischemia. Hyperglycemia (blood glucose more than 22.2 mmol/L) was induced by glucose administration with or without IPC during different phases (trigger- (before ischemia), mediator- (during ischemia), early reperfusion-phase). One additional group received an anti-PMN-antibody before ischemia. Infarct size was quantified by triphenyltetrazolium chloride staining. Cytochrome C release and B-cell lymphoma two (Bcl-2) expression were assessed by western blot analysis. Poly-ADP-Ribose staining and PMN accumulation were quantified with immunohistochemistry and histochemistry.

RESULTS

IPC reduced infarct size compared with control. Hyperglycemia completely abolished IPC-induced cardioprotection independent of the time point of initiation. Hyperglycemia before and during major ischemia but without IPC also slightly reduced infarct size. IPC reduced the accumulation of PMNs. This effect was reversed by hyperglycemia during trigger- and mediator-phase but not by hyperglycemia during reperfusion. Hyperglycemia alone had no effect on PMN accumulation. In all treatment groups, signs of myocardial apoptosis were reduced compared with control. IPC alone, combined with hyperglycemia and anti-PMN treatment, reduced apoptosis by a Bcl-2-associated mechanism. Hyperglycemia alone reduced apoptosis by a Bcl-2-independent pathway.

CONCLUSION

Hyperglycemia inhibits IPC-induced cardioprotection independent of its onset. Furthermore, hyperglycemia prevents apoptosis and IPC-induced reduction of PMN aggregation.

Effect of ischemic preconditioning on cardiovascular outcomes in patients with symptomatic coronary artery disease: a cohort study

BACKGROUND

Despite the powerful myocardial protection of ischemic preconditioning (IP) observed in experimental studies, it remains a challenge to observe such protection in humans. Thus, the aim of this study was to evaluate the possible effects of IP on clinical outcomes in patients with coronary artery disease (CAD).

PATIENTS AND METHODS

In this cohort study, patients with multivessel CAD, preserved systolic ventricular function, and stable angina were prospectively selected. They underwent two sequential exercise stress tests (EST) to evaluate IP presence. IP was considered present if patients had an improvement in the time to the onset of 1.0-mm STsegment deviation in the second EST. The primary end point was the composite rate of cardiac death, nonfatal myocardial infarction, or revascularization during 1-year follow-up. Patients with (IP+) and without (IP-) the cardioprotective mechanism were compared regarding clinical end points.

RESULTS

A total of 229 patients completed EST and had IP evaluated: 165 (72%) were IP+ and 64 (28%) were IP - patients. Of these, 218 patients had complete follow-up. At 1-year, event-free survival regarding the primary end point was 95.5 versus 83.6% (P = 0.0024) and event-free survival regarding cardiac death or myocardial infarction was 99.4 versus 91.7% (P=0.0020), respectively, in IP + and IP - groups. The unadjusted hazard ratio (IP + /IP-) for the primary end point was 4.63 (1.52-14.08). After multivariate analysis, IP was still significantly associated with better clinical outcomes (P = 0.0025).

CONCLUSION

This data suggest that IP may contribute to better clinical outcomes in patients with ischemic heart disease.

The Role of Sodium in Diabetic Cardiomyopathy

Cardiovascular complications are the major cause of mortality and morbidity in diabetic patients. The changes in myocardial structure and function associated with diabetes are collectively called diabetic cardiomyopathy. Numerous molecular mechanisms have been proposed that could contribute to the development of diabetic cardiomyopathy and have been studied in various animal models of type 1 or type 2 diabetes. The current review focuses on the role of sodium (Na⁺) in diabetic cardiomyopathy and provides unique data on the linkage between Na⁺ flux and energy metabolism, studied with non-invasive ²³Na, and ³¹P-NMR spectroscopy, polarography, and mass spectroscopy. ²³Na NMR studies allow determination of the intracellular and extracellular Na⁺ pools by splitting the total Na⁺ peak into two resonances after the addition of a shift reagent to the perfusate. Using this technology, we found that intracellular Na⁺ is approximately two times higher in diabetic cardiomyocytes than in control possibly due to combined changes in the activity of Na⁺–K⁺ pump, Na⁺/H⁺ exchanger 1 (NHE1) and Na⁺-glucose cotransporter. We hypothesized that the increase in Na⁺ activates the mitochondrial membrane Na⁺/Ca²⁺ exchanger, which leads to a loss of intramitochondrial Ca²⁺, with a subsequent alteration in mitochondrial bioenergetics and function. Using isolated mitochondria, we showed that the addition of Na⁺ (1–10 mM) led to a dose-dependent decrease in oxidative phosphorylation and that this effect was reversed by providing extramitochondrial Ca²⁺ or by inhibiting the mitochondrial Na⁺/Ca²⁺ exchanger with diltiazem. Similar experiments with ³¹P-NMR in isolated superfused mitochondria embedded in agarose beads showed that Na⁺ (3–30 mM) led to significantly decreased ATP levels and that this effect was stronger in diabetic rats. These data suggest that in diabetic cardiomyocytes, increased Na⁺ leads to abnormalities in oxidative phosphorylation and a subsequent decrease in ATP levels. In support of these data, using ³¹P-NMR, we showed that the baseline β-ATP and phosphocreatine (PCr) were lower in diabetic cardiomyocytes than in control, suggesting that diabetic cardiomyocytes have depressed bioenergetic function. Thus, both altered intracellular Na⁺ levels and bioenergetics and their interactions may significantly contribute to the pathology of diabetic cardiomyopathy.

Mitochondrial aldehyde dehydrogenase obliterates insulin resistance-induced cardiac dysfunction through deacetylation of PGC-1α

Insulin resistance contributes to the high prevalence of type 2 diabetes mellitus, leading to cardiac anomalies. Emerging evidence depicts a pivotal role for mitochondrial injury in oxidative metabolism and insulin resistance. Mitochondrial aldehyde dehydrogenase (ALDH2) is one of metabolic enzymes detoxifying aldehydes although its role in insulin resistance remains elusive. This study was designed to evaluate the impact of ALDH2 overexpression on insulin resistance-induced myocardial damage and mechanisms involved with a focus on autophagy. Wild-type (WT) and transgenic mice overexpressing ALDH2 were fed sucrose or starch diet for 8 weeks and cardiac function and intracellular Ca²⁺ handling were assessed using echocardiographic and IonOptix systems. Western blot analysis was used to evaluate Akt, heme oxygenase-1 (HO-1), PGC-1α and Sirt-3. Our data revealed that sucrose intake provoked insulin resistance and compromised fractional shortening, cardiomyocyte function and intracellular Ca²⁺ handling (p < 0.05) along with unaltered cardiomyocyte size (p > 0.05), mitochondrial injury (elevated ROS generation, suppressed NAD+ and aconitase activity, p < 0.05 for all), the effect of which was ablated by ALDH2. In vitro incubation of the ALDH2 activator Alda-1, the Sirt3 activator oroxylin A and the histone acetyltransferase inhibitor CPTH2 rescued insulin resistance-induced changes in aconitase activity and cardiomyocyte function (p < 0.05). Inhibiting Sirt3 deacetylase using 5-amino-2-(4-aminophenyl) benzoxazole negated Alda-1-induced cardioprotective effects. Taken together, our data suggest that ALDH2 serves as an indispensable cardioprotective factor against insulin resistance-induced cardiomyopathy with a mechanism possibly associated with facilitation of the Sirt3-dependent PGC-1α deacetylation.

Hyperoxia-induced cardiotoxicity and ventricular remodeling in type-II diabetes mice

Hyperoxia, or supplemental oxygen, is regularly used in the clinical setting for critically ill patients in ICU. However, several recent studies have demonstrated the negative impact of this treatment in patients in critical care, including increased rates of lung and cardiac injury, as well as increased mortality. The purpose of this study was to determine the predisposition for arrhythmias and electrical remodeling in a type 2 diabetic mouse model (db/db), as a result of hyperoxia treatment. For this, db/db and their heterozygous controls were treated with hyperoxia (> 90% oxygen) or normoxia (normal air) for 72-h. Immediately following hyperoxia or normoxia treatments, mice underwent surface ECG. Excised left ventricles were used to assess ion channel expression, including for Kv1.4, Kv1.5, Kv4.2, and KChIP2. Serum cardiac markers were also measured, including cardiac troponin I and lactate dehydrogenase. Our results showed that db/db mice have increased sensitivity to arrhythmia. Normoxia-treated db/db mice displayed features of arrhythmia, including QTc and JT prolongation, as well as QRS prolongation. A significant increase in QRS prolongation was also observed in hyperoxia-treated db/db mice, when compared to hyperoxia-treated heterozygous control mice. Db/db mice were also shown to exhibit ion channel dysregulation, as demonstrated by down-regulation in Kv1.5, Kv4.2, and KChIP2 under hyperoxia conditions. From these results, we conclude that: (1) diabetic mice showed distinct pathophysiology, when compared to heterozygous controls, both in normoxia and hyperoxia conditions. (2) Diabetic mice were more susceptible to arrhythmia at normal air conditions; this effect was exacerbated at hyperoxia conditions. (3) Unlike in heterozygous controls, diabetic mice did not demonstrate cardiac hypertrophy as a result of hyperoxia. (4) Ion channel remodeling was also observed in db/db mice under hyperoxia condition similar to its heterozygous controls.

Myocyte membrane and microdomain modifications in diabetes: determinants of ischemic tolerance and cardioprotection

Cardiovascular disease, predominantly ischemic heart disease (IHD), is the leading cause of death in diabetes mellitus (DM). In addition to eliciting cardiomyopathy, DM induces a ‘wicked triumvirate’: (i) increasing the risk and incidence of IHD and myocardial ischemia; (ii) decreasing myocardial tolerance to ischemia–reperfusion (I–R) injury; and (iii) inhibiting or eliminating responses to cardioprotective stimuli. Changes in ischemic tolerance and cardioprotective signaling may contribute to substantially higher mortality and morbidity following ischemic insult in DM patients. Among the diverse mechanisms implicated in diabetic impairment of ischemic tolerance and cardioprotection, changes in sarcolemmal makeup may play an overarching role and are considered in detail in the current review. Observations predominantly in animal models reveal DM-dependent changes in membrane lipid composition (cholesterol and triglyceride accumulation, fatty acid saturation vs. reduced desaturation, phospholipid remodeling) that contribute to modulation of caveolar domains, gap junctions and T-tubules. These modifications influence sarcolemmal biophysical properties, receptor and phospholipid signaling, ion channel and transporter functions, contributing to contractile and electrophysiological dysfunction, cardiomyopathy, ischemic intolerance and suppression of protective signaling. A better understanding of these sarcolemmal abnormalities in types I and II DM (T1DM, T2DM) can inform approaches to limiting cardiomyopathy, associated IHD and their consequences. Key knowledge gaps include details of sarcolemmal changes in models of T2DM, temporal patterns of lipid, microdomain and T-tubule changes during disease development, and the precise impacts of these diverse sarcolemmal modifications. Importantly, exercise, dietary, pharmacological and gene approaches have potential for improving sarcolemmal makeup, and thus myocyte function and stress-resistance in this ubiquitous metabolic disorder.

Comparison of Clinical Characteristics and Outcomes of Patients With Versus Without Diabetes Mellitus and With Versus Without Angina Pectoris (from the Duke Databank for Cardiovascular Disease)

Angina pectoris (AP) has different prognostic implications in various populations. Patients with diabetes mellitus (DM) may experience neuropathy such that AP may not be perceived in the setting of coronary artery disease (CAD). The prognostic utility of AP in DM patients with CAD is not well known. We analyzed patients with CAD who underwent coronary angiography at Duke University from 2002 to 2011 and compared patients with and without AP within the previous 6 weeks stratified by DM status. We used multivariable Cox regression to assess the association between AP and the outcomes of cardiovascular (CV) hospitalization/revascularization, all-cause mortality/myocardial infarction/revascularization, and all-cause mortality. Of 17,211 patients with CAD, 5,284 (31%) had DM and AP was present in 69% of DM and 67% of non-DM. After risk adjustment, the risk of CV hospitalization/revascularization and all-cause mortality/myocardial infarction/revascularization in patients with and without AP was similar regardless of DM status (all p ≥0.05). In patients with or without DM, AP was associated with lower all-cause mortality compared with no AP (adjusted hazard ratio 0.89, 95% confidence interval 0.82 to 0.97, p = 0.005 for DM patients). The relation between AP status and clinical outcomes was not dependent on DM status (all interaction p >0.10). In conclusion, in patients with CAD, AP was associated with similar risk for CV hospitalization and revascularization and lower all-cause mortality compared with patients without AP regardless of DM status. Future studies are needed to assess whether these findings are related to increased severity of disease in those without AP or whether AP leads to differential management that improves survival.

Myocardial injury in diabetic patients with multivessel coronary artery disease after revascularization interventions

BACKGROUND

Diabetic patients may be more susceptible to myocardial injury after coronary interventions. Thus, the aim of this study was to assess the release of cardiac biomarkers, CK-MB and troponin, and the findings of new late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) in patients with type 2 diabetes mellitus after elective revascularization procedures for multivessel coronary artery disease (CAD).

METHODS

Patients with multivessel CAD and preserved systolic ventricular function underwent either elective percutaneous coronary intervention (PCI), off-pump or on-pump bypass surgery (CABG). Troponin and CK-MB were systematically collected at baseline, 6, 12, 24, 36, 48 and 72 h after the procedures. CMR with LGE was performed before and after the interventions. Patients were stratified according to diabetes status at study entry. Biomarkers and CMR results were compared between diabetic and nondiabetics patients. Analyses of correlation were also performed among glycemic and glycated hemoglobin (A1c) levels and troponin and CK-MB peak levels. Patients were also stratified into tertiles of fasting glycemia and A1c levels and were compared in terms of periprocedural myocardial infarction (PMI) on CMR.

RESULTS

Ninety (44.5%) of the 202 patients had diabetes mellitus at study entry. After interventions, median peak troponin was 2.18 (0.47, 5.14) and 2.24 (0.69, 5.42) ng/mL (P = 0.81), and median peak CK-MB was 14.1 (6.8, 31.7) and 14.0 (4.2, 29.8) ng/mL (P = 0.43), in diabetic and nondiabetic patients, respectively. The release of troponin and CK-MB over time was statistically similar in both groups and in the three treatments, besides PCI. New LGE on CMR indicated that new myocardial fibrosis was present in 18.9 and 17.3% (P = 0.91), and myocardial edema in 15.5 and 22.9% (P = 0.39) in diabetic and nondiabetic patients, respectively. The incidence of PMI in the glycemia tertiles was 17.9% versus 19.3% versus 18.7% (P = 0.98), and in the A1c tertiles was 19.1% versus 13.3% versus 22.2% (P = 0.88).

CONCLUSIONS

In this study, diabetes mellitus did not add risk of myocardial injury after revascularization interventions in patients with multivessel coronary artery disease. Trial Registration Name of Registry: Evaluation of cardiac biomarker elevation after percutaneous coronary intervention or coronary artery bypass graft; URL: http://www.controlled-trials.com.ISRCTN09454308.

Change in left ventricular systolic function in patients with ST elevation myocardial infarction: Evidence for smoker's paradox or pseudo-paradox?

Background

The ‘smoker's paradox’ refers to the observation of favorable prognosis in current smokers following an acute ST elevation myocardial infarction (STEMI) in the era of fibrinolysis, however, several STEMI studies have demonstrated conflicting results in patients undergoing primary percutaneous coronary intervention (p-PCI).

Objective

Aim of the current study was to evaluate the impact of cigarette smoking on left ventricular function in STEMI patients undergoing p-PCI.

Methods

Our population is represented by 74 first-time anterior STEMI patients undergoing p-PCI, 37 of whom were smokers. We assessed left ventricular function by left ventricular ejection fraction (LVEF) on the second day after admission and at 3-month follow-up. Early predictors of adverse left ventricular remodelling after STEMI treated by p-PCI were examined.

Results

Basal demographics and comorbidities were similar between groups. Although the LVEF during the early phase was higher in smokers compared to non-smokers (44.95 ± 7.93% vs. 40.32 ± 7.28%; p = 0.011); it worsened in smokers at follow-up (mean decrease in LVEF: −2.70 ± 5.95%), whereas it improved in non-smokers (mean recovery of LVEF: +2.97 ± 8.45%). In univariate analysis, diabetes mellitus, peak troponin I, current smoking, and lower TIMI flow grade after p-PCI, pain-to-door time and door-to-balloon times were predictors of adverse left ventricular remodelling. After multivariate logistic regression analysis, smoking at admission, lower TIMI flow grade after p-PCI, the pain-to-door time and door-to-balloon times remained independent predictors of deterioration in LVEF.

Conclusion

True or persistent ‘smoker's paradox’ does not appear to be relevant among STEMI patients undergoing p-PCI. The ‘smoker's paradox’ is in fact a pseudo-paradox. Further studies with larger numbers may be warranted.

The pattern of circulating microparticles in patients with diabetes mellitus with asymptomatic atherosclerosis

BACKGROUND

Accelerating atherosclerosis in type 2 diabetes mellitus (T2DM) patients may relate to imbalance between pattern of microparticles (MPs), which are frequently involved in repair of vasculature, tissue injury, inflammation and thrombosis. The aim of the study was to investigate the pattern of circulating MPs in T2DM patients with asymptomatic atherosclerosis.

METHODS

A total of 103 patients with T2DM (54 subjects without documented coronary atherosclerosis and 49 patients with angiographic evidence of asymptomatic coronary atherosclerosis) who were underwent a contrast-enhanced multispiral computed tomography angiography and 35 healthy volunteers were enrolled in the study. To determine circulating biomarkers, blood samples were collected at baseline. MPs were labelled and characterized by flow cytometry.

RESULTS

There were no significant differences between healthy volunteers and T2DM patients in circulating numbers of MPs labelled as CD41a+, CD64+, CD144+, CD144+/CD31+, Annexin V+, CD144+/annexin V+ and CD144+/CD31+/annexin V+. However, lower number of MPs with immune phenotypes CD62E+, CD105E+ and higher numbers of CD31+/annexin V+ MPs were reported in T2DM patients when compared with healthy volunteers. Therefore, we found an increased level of circulating CD41a+ MPs, CD144+/CD31+ MPs, CD31+/annexin V+ MPs, and decreased level of CD62E+ MPs in T2DM patients with asymptomatic coronary atherosclerosis in comparison with those who had no asymptomatic atherosclerosis. Using multivariate log regression analysis, BMI (odds ratio [OR] = 1.04, p = 0.001), LDL-C (OR = 1.05, p = 0.046), hs-CRP (OR = 1.07, p = 0.044), osteoprotegerin (OR = 1.07, p = 0.026), CD62E+ MPs (OR = 1.07, p = 0.001) and CD31+/annexin V+ MPs (OR = 1.12, p = 0.003) were determined independent predictive factors of asymptomatic atherosclerosis in T2DM patients.

CONCLUSION

Circulating levels of MP originated from apoptotic endothelial cell-derived were significantly increased in diabetic patients as compared with normal subjects, but level of activated endothelial cell-derived MPs was lower than in healthy volunteers. Among T2DM patients, an increased level of CD31+/annexin V+ MPs and decreased CD62E+ MPs were significantly associated with asymptomatic atherosclerosis.

The Influence of Diabetes Mellitus in Myocardial Ischemic Preconditioning

Ischemic preconditioning (IP) is a powerful mechanism of protection discovered in the heart in which ischemia paradoxically protects the myocardium against other ischemic insults. Many factors such as diseases and medications may influence IP expression. Although diabetes poses higher cardiovascular risk, the physiopathology underlying this condition is uncertain. Moreover, although diabetes is believed to alter intracellular pathways related to myocardial protective mechanisms, it is still controversial whether diabetes may interfere with ischemic preconditioning and whether this might influence clinical outcomes. This review article looks at published reports with animal models and humans that tried to evaluate the possible influence of diabetes in myocardial ischemic preconditioning.