The effect of statin therapy on endothelial function in type 2 diabetes without manifest cardiovascular disease

Pharmacological effects of statins in adult patients with type 2 diabetes mellitus: A protocol for systematic review and meta-analysis

BACKGROUND

Due to contradicting findings on impact of statins on endothelial function in type 2 diabetes mellitus especially across the randomized controlled trials (RCTs). With this systematic review, we aim to evaluate whether the use of statins improves endothelial function in adults with type 2 diabetes. We will further highlight if these biomarkers are ideal therapeutic targets for risk for atherosclerosis and cardiovascular disease.

METHODS

This protocol was carried out according to the preferred reporting items for systematic review and meta-analysis protocols-2015 guideline. The online databases, such as MEDLINE, Scopus, and Web of Sciences, will be targeted using the medical subject heading terms (MeSH) and text words. The review will include clinical studies on the effect of statins on markers of endothelial function in type 2 diabetes. The Cochrane risk of bias guideline will be used to assess the quality and risk of bias. We are planning to use the grading of recommendation assessment, development, and evaluation approach to evaluate the strength and quality of evidence.

RESULTS

This study will not involve human samples and patient data; hence ethics approval will not be required. The findings will be presented in journal clubs and conferences and published in peer-reviewed journals.

Effect of Atorvastatin on Microcirculation Evaluated by Vascular Occlusion Test with Peripheral Near-Infrared Spectroscopy

The vascular occlusion test (VOT) with peripheral near-infrared spectroscopy (NIRS) is a non-invasive method to evaluate peripheral microcirculation. Statin therapy is widely used for patients with dyslipidaemia and contributes to reducing low-density lipoprotein cholesterol (LDL-C) levels and adverse cardiovascular events. However, it is not yet clear whether statin treatment improves peripheral microcirculation assessed by VOT with NIRS. In the present study, using VOT with NIRS, we evaluated the effect of statin therapy on peripheral microcirculation in patients with dyslipidaemia before and after statin therapy.

METHODS

A total of six consecutive patients with dyslipidaemia who had not received statin therapy (6 males, mean age 71.8 ± 7.4 years) were enrolled. All patients were administered atorvastatin and their peripheral microcirculation assessed using VOT with NIRS (NIRO-200NX, Hamamatsu Photonics K.K., Japan) before and after statin therapy. The NIRS probe was attached to the right thenar eminence and brachial artery blood flow was blocked for 3 min at 50 mmHg above the resting systolic blood pressure. Maximum and minimum values of NIRS parameters after the VOT were used to determine concentration changes for total haemoglobin (ΔcHb), oxyhaemoglobin (ΔO2Hb), deoxyhaemoglobin (ΔHHb), and tissue oxygenation index (ΔTOI).

RESULTS

During the follow-up period (mean 30.3 ± 6.5 days), LDL-C level decreased from 129.7 ± 26.3 to 67.5 ± 20.2 mg/dL (p-value = 0.031), ΔTOI increased from 24.0 ± 5.3 to 33.7 ± 6.3% (p-value = 0.023), and ΔO2Hb increased from 16.4 ± 5.3 to 20.0 ± 6.6 μmol/L (p-value = 0.007). ΔcHb and ΔHHb did not change significantly.

CONCLUSION

ΔO2Hb and ΔTOI were significantly increased during the follow-up period. These findings suggest that ΔO2Hb and ΔTOI could assess the improvement of peripheral microcirculation by statin therapy. Compared to ΔTOI, ΔO2Hb seems to be a more useful parameter to evaluate peripheral microcirculation.

Low Levels of Low-Density Lipoprotein Cholesterol and Endothelial Function in Subjects without Lipid-Lowering Therapy

An elevation of serum low-density lipoprotein cholesterol (LDL-C) levels has been associated with endothelial dysfunction in statin naïve subjects. However, there is no information on endothelial function in subjects with extremely low levels of LDL-C. The purpose of the present study was to determine the relationship of LDL-C levels, especially low levels of LDL-C, with endothelial function. Endothelial function assessed by flow-mediated vasodilation (FMD) measurement and LDL-C levels were evaluated in 7120 subjects without lipid-lowering therapy. We divided the subjects into five groups by LDL-C levels: <70 mg/dL, 70-99 mg/dL, 100-119 md/dL, 120-139 mg/dL, and ≥140 mg/dL. FMD values were significantly smaller in subjects with LDL-C levels of ≥140 mg/dL than in those with LDL-C levels of 70-99 mg/dL and 100-119 mg/dL (p < 0.001 and p = 0.004, respectively). The FMD values in the LDL-C of <70 mg/dL group were not significantly different from those in the other groups. To evaluate the relationship of extremely low LDL-C levels with endothelial function, we divided the subjects with LDL-C of <70 mg/dL into those with LDL-C levels of <50 mg/dL and 50-69 mg/dL. FMD values were similar in the LDL-C <50 mg/dL group and ≥50 mg/dL group in the propensity score-matched population (p = 0.570). A significant benefit was not found in subjects with low LDL-C levels from the aspect of endothelial function.

Statin Therapy Before Transition to End-Stage Renal Disease With Posttransition Outcomes

Background Although studies have shown that statin therapy in patients with non-dialysis-dependent chronic kidney disease was associated with a lower risk of death, this was not observed in dialysis patients newly initiated on statins. It is unclear if statin therapy benefits administered during the predialysis period persist after transitioning to end-stage renal disease. Methods and Results In 47 720 veterans who transitioned to end-stage renal disease during 2007 to 2014, we examined the association of statin therapy use 1 year before transition with posttransition all-cause and cardiovascular mortality and hospitalization incidence rates over the first 12 months of follow-up. Associations were examined using multivariable adjusted Cox proportional hazard models and negative binomial regressions. Sensitivity analyses included propensity score and subgroup analyses. The cohort's mean± SD age was 71±11 years, and the cohort included 4% women, 23% blacks, and 66% diabetics. Over 12 months of follow-up, there were 13 411 deaths, with an incidence rate of 35.3 (95% CI , 34.7-35.8) deaths per 100 person-years. In adjusted models, statin therapy compared with no statin therapy was associated with lower risks of 12-month all-cause (hazard ratio [95% CI], 0.79 [0.76-0.82]) and cardiovascular (hazard ratio [95% CI ], 0.83 [0.78-0.88]) mortality, as well as with a lower rate of hospitalizations (incidence rate ratio [95% CI ], 0.89 [0.87-0.92]) after initiating dialysis. These lower outcome risks persisted across strata of clinical characteristics, and in propensity score analyses. Conclusions Among veterans with non-dialysis-dependent chronic kidney disease, treatment with statin therapy within the 1 year before transitioning to end-stage renal disease is associated with favorable early end-stage renal disease outcomes.

Effects of combined statin and ACE inhibitor therapy on endothelial function and blood pressure in essential hypertension - a randomised double-blind, placebo controlled crossover study

Background:

The aim of this study was to compare the influence of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors on endothelial function and blood pressure in patients with essential hypertension on long-term angiotensin-converting enzyme inhibitor therapy.

Method:

The study was designed as a prospective, double-blind, randomised, placebo controlled, crossover clinical trial. Twenty patients with essential hypertension were treated with an angiotensin-converting enzyme inhibitor; the control group included 10 healthy subjects. Hypertensive patients received in random order 80 mg of fluvastatin daily or placebo for 6 weeks. The following parameters were assessed at baseline and after each treatment period: serum lipids, flow-mediated vasodilation, activity of von Willebrand factor, concentration of vascular endothelial growth factor, C-reactive protein and 24-hour blood pressure profile.

Results:

Hypertensive patients did not differ from healthy subjects with respect to age, body mass and biochemical parameters, with the exception of C-reactive protein, which was higher in hypertensive patients (P=0.02). After statin therapy, low-density lipoprotein cholesterol (P<0.0001), C-reactive protein (P=0.03), von Willebrand factor (P=0.03) and vascular endothelial growth factor (P<0.01) decreased and flow-mediated vasodilation improved (P<0.001). Statins had no significant effect on blood pressure.

Conclusions:

Statins added to angiotensin-converting enzyme inhibitors may improve endothelial function and ameliorate inflammation independently of blood pressure.

New potentials for 3-hydroxy-3-methyl-glutaryl-coenzymeA reductase inhibitors: Possible applications in retarding diabetic complications

The prevalence of diabetes mellitus is increasing all over the world and it is apparent that treatment of diabetic complications has the same importance as primary diabetes treatment and glycemic control. Diabetic complications occur as a result of prolonged hyperglycemia and its consequences, such as advanced glycation end products and reactive oxygen species. Impairment of lipid profile is also contributed to worsening diabetic complications. Therefore, it seems that the application of lipid-lowering agents may have positive effects on reversing diabetic complications besides glycemic control. Statins, a group of lipid-lowering compounds, have been shown to exert antioxidant, immunomodulatory, anti-inflammatory, and antiproliferative properties beyond their lipid-lowering effects. Furthermore, they have been reported to improve diabetic complications with different pathways. In this review, we will discuss the clinical importance, molecular biology of the most important microvascular/macrovascular diabetic complications, possible application of statins and their mechanism of action in retarding these complications.

Effect of Aggressive lipid-lowering treatment with Rosuvastatin on vascular endoTHelium function: evaluation of vascular endothelium function (EARTH study)

Vascular endothelial dysfunction plays an important role in the process of atherosclerosis up to the final stage of plaque rupture. Vascular endothelial dysfunction is reversible, and can be recovered by medications and life-style changes. Improvement in endothelial function may reduce cardiovascular events and improve long-term prognosis. A total of 50 patients with stable angina and dyslipidemia were enrolled, including patients who had not received prior treatment with statins and had serum LDL-C levels ≥ 100 mg/dL, and patients who had previously received statin treatment. All agreed to register regardless of their LDL-C level. Rosuvastatin was initially administered at a dose of 2.5 mg and appropriately titrated up to the maximum dose of 20 mg or until LDL-C levels lower than 80 mg/dL were achieved, for 24 weeks. Endothelial function was assessed by the reactive hyperemia peripheral arterial tonometry (RH-PAT) index in the radial artery by Endo-PAT^® 2000 (Endo-PAT^®2000, software version 3.0.4, Itamar Medical Ltd., Caesarea, Israel). RH-PAT data were digitally analyzed online by Endo-PAT^®2000 at baseline and at 24 weeks. LDL-C and MDA-LDL-C decreased from 112.6 ± 23.3 to 85.5 ± 20.2 mg/dL and from 135.1 ± 36.4 to 113.9 ± 23.5 mg/dL respectively (p < 0.0001). However, HDL-C, hs-CRP and TG did not change significantly after treatment. RH-PAT index levels significantly improved, from 1.60 ± 0.31 to 1.77 ± 0.57 (p = 0.04) after treatment, and the percent change of the RH-PAT index was 12.8 ± 36.9%. Results of multivariate analysis show that serum LDL-C levels over 24 weeks did not act as a predictor of improvement of the RH-PAT index. However, HbA1c at baseline was an independent predictor which influenced the 24-week RH-PAT index level. The RH-PAT index of patients with high HbA1c at baseline did not improve after administration of rosuvastatin but it did improve in patients with low HbA1c at baseline. Aggressive lowering of LDL-C with rosuvastatin significantly improved the RH-PAT index, suggesting that it may improve endothelial function in patients with coronary artery disease.Clinical Trial Registration No: UMIN-CTR, UMIN000010040.

The Central Role of Endothelial Dysfunction in Cardiorenal Syndrome

BACKGROUND

Endothelial dysfunction (ED) has emerged as a critical process in cardiorenal syndrome (CRS). The concept that ED is closely linked with cardiac and renal dysfunction has become an important target for CRS-related research and clinical practice.

SUMMARY

The sequence of events leading to ED is initiated by type I endothelial activation (almost immediately) and type II endothelial activation (over hours, days, and even months), followed by endothelial apoptosis and endothelial necrosis. The fact that ED is a continual cellular event divides this process into reversible ED (endothelial activation) and irreversible ED (endothelial apoptosis and necrosis). This basic research-defined concept may have clinical implications. Although most antihypertensive drugs (ACE inhibitors, statins, etc.) are effective in patients with hypertension and diabetes, some of them have proved to be ineffective, which may partly be attributed to irreversible ED. Even though the etiology of ED consists mainly of asymmetric dimethylarginine, nitric oxide, oxidative stress, and anti-endothelial cell antibodies, many other inducers of ED have been identified. In addition, a distinct role of ED has been reported for each type of CRS in humans.

KEY MESSAGES

Further study is warranted to prove whether ED holds promise as a pharmacological target in CRS patients.

Renin-Angiotensin System Blockade Associated with Statin Improves Endothelial Function in Diabetics

Background

Studies suggest that statins have pleiotropic effects, such as reduction in blood pressure, and improvement in endothelial function and vascular stiffness.

Objective

To analyze if prior statin use influences the effect of renin-angiotensin-aldosterone system inhibitors on blood pressure, endothelial function, and vascular stiffness.

Methods

Patients with diabetes and hypertension with office systolic blood pressure ≥ 130 mmHg and/or diastolic blood pressure ≥ 80 mmHg had their antihypertensive medications replaced by amlodipine during 6 weeks. They were then randomized to either benazepril or losartan for 12 additional weeks while continuing on amlodipine. Blood pressure (assessed with ambulatory blood pressure monitoring), endothelial function (brachial artery flow-mediated dilation), and vascular stiffness (pulse wave velocity) were evaluated before and after the combined treatment. In this study, a post hoc analysis was performed to compare patients who were or were not on statins (SU and NSU groups, respectively).

Results

The SU group presented a greater reduction in the 24-hour systolic blood pressure (from 134 to 122 mmHg, p = 0.007), and in the brachial artery flow-mediated dilation (from 6.5 to 10.9%, p = 0.003) when compared with the NSU group (from 137 to 128 mmHg, p = 0.362, and from 7.5 to 8.3%, p = 0.820). There was no statistically significant difference in pulse wave velocity (SU group: from 9.95 to 9.90 m/s, p = 0.650; NSU group: from 10.65 to 11.05 m/s, p = 0.586).

Conclusion

Combined use of statins, amlodipine, and renin-angiotensin-aldosterone system inhibitors improves the antihypertensive response and endothelial function in patients with hypertension and diabetes.

A pilot study of ezetimibe vs. atorvastatin for improving peripheral microvascular endothelial function in stable patients with type 2 diabetes mellitus

BACKGROUND

Elevated cholesterol in type 2 diabetes mellitus (DM) can cause endothelial dysfunction. An effective clinical therapy to improve endothelial dysfunction remains to be established. Different cardiovascular actions between treatments for the inhibition of cholesterol absorption and the suppression of cholesterol synthesis for achieving improvement in endothelial function are unknown in DM.

METHODS

Stable patients with type 2 DM and mildly elevated low-density lipoprotein cholesterol were enrolled. We evaluated peripheral microvascular endothelial function using reactive hyperemia peripheral arterial tonometry (RH-PAT) examination and calculated a natural logarithmic transformed value for the RH-PAT index (LnRHI). We randomly assigned 33 patients to each monotherapy: cholesterol synthesis suppression using atorvastatin (5 mg/day, n=16) or cholesterol absorption inhibition using ezetimibe (10 mg/day, n=17). Patients were prospectively followed for 6 months. Serum lipids and LnRHI were repeatedly examined before and after each therapy.

RESULTS

LDL significantly decreased in both groups, but the percent changes of LDL showed a greater decrease in the atorvastatin group compared with the ezetimibe group (-34.5±7.8% vs. -21.9±9.6%, p<0.01). Serum levels of non-esterified free fatty acids (NEFA) significantly decreased in the ezetimibe group but not in the atorvastatin group (ezetimibe group: 561.1±236.8 to 429.7±195.9, p<0.01; atorvastatin group: 538.8±319.5 to 520.2±227.3, p=0.75). The percent decrease in NEFA was significantly greater in the ezetimibe group compared with the atorvastatin group (-19.9±27.4% vs. 11.3±44.1%, p<0.05). LnRHI showed a significant increase in the ezetimibe group but not in the atorvastatin group (ezetimibe group: 0.471±0.157 to 0.678±0.187, p<0.01; atorvastatin group: 0.552±0.084 to 0.558±0.202, p=0.64). The percent changes in LnRHI were significantly greater in the ezetimibe group compared with the atorvastatin group (63.3±89.2% vs. 7.4±41.2%, p<0.05).

CONCLUSIONS

In patients with type 2 DM, ezetimibe monotherapy significantly reduced LDL and NEFA, and improved peripheral microvascular endothelial dysfunction. Ezetimibe could potentially exhibit beneficial effects on lipid disorders and microvascular endothelial dysfunction in DM.

Endothelial dysfunction in conduit arteries and in microcirculation. Novel therapeutic approaches

The vascular endothelium not only is a single monolayer of cells between the vessel lumen and the intimal wall, but also plays an important role by controlling vascular function and structure mainly via the production of nitric oxide (NO). The so called "cardiovascular risk factors" are associated with endothelial dysfunction, that reduces NO bioavailability, increases oxidative stress, and promotes inflammation contributing therefore to the development of atherosclerosis. The significant role of endothelial dysfunction in the development of atherosclerosis emphasizes the need for efficient therapeutic interventions. During the last years statins, angiotensin-converting enzyme inhibitors, angiotensin-receptor antagonists, antioxidants, beta-blockers and insulin sensitizers have been evaluated for their ability to restore endothelial function (Briasoulis et al., 2012). As there is not a straightforward relationship between therapeutic interventions and improvement of endothelial function but rather a complicated interrelationship between multiple cellular and sub-cellular targets, research has been focused on the understanding of the underlying mechanisms. Moreover, the development of novel diagnostic invasive and non-invasive methods has allowed the early detection of endothelial dysfunction expanding the role of therapeutic interventions and our knowledge. In the current review we present the available data concerning the contribution of endothelial dysfunction to atherogenesis and review the methods that assess endothelial function with a view to understand the multiple targets of therapeutic interventions. Finally we focus on the classic and novel therapeutic approaches aiming to improve endothelial dysfunction and the underlying mechanisms.

Multiple risk factor intervention reduces carotid atherosclerosis in patients with type 2 diabetes

Background

Patients with rapid progression of carotid intima media thickness (CIMT) were shown to have a higher future risk for cardiovascular events.

The aim of this study was to investigate the impact of multiple risk factor intervention on CIMT progression and to establish whether new cardiovascular surrogate measurements would allow prediction of CIMT changes.

Materials and methods

In this prospective, open, 2-years study, we included 97 patients with type 2 diabetes and at least two insufficiently treated cardiovascular risk factors, i.e. HbA_1c > 7.5% (58 mmol/mol); LDL-cholesterol >3.1 mmol/l or blood pressure >140/90 mmHg. Treatment was intensified according to current guidelines over 3 months with the aim to maintain intensification over 2 years.

The primary outcome was the change in CIMT after 2 years. We also assessed markers of mechanical and biochemical endothelial function and endothelial progenitor cells before and after 3 months of treatment intensification. For testing differences between before and after multifactorial treatment measurements we used either the paired student’s t-test or the Wilcoxon signed-rank test, depending on the distribution of the data. Additional, explorative statistical data analysis was done on CIMT progression building a linear multivariate regression model.

Results

Blood glucose, lipids and blood pressure significantly improved during the first 3 months of intensified treatment, which was sustained over the 2-year study duration. Mean CIMT significantly decreased from baseline to 2 year (0.883 ± 0.120 mm vs. 0.860 ± 0.130 mm; p = 0.021). None of the investigated surrogate measures, however, was able to predict changes in IMT early after treatment intensification.

Conclusions

Intensification of risk factor intervention in type 2 diabetes results in CIMT regression over a period of 2 years. None of the biomarkers used including endothelial function parameters or endothelial progenitor cells turned out to be useful to predict CIMT changes.

Trial registration

Clinical Trial Registration – Unique identifier: NCT00660790

HMG-CoA reductase inhibitors (statins), inflammation, and endothelial progenitor cells-New mechanistic insights of atherosclerosis

Statins have been shown to favorably affect the prognosis of patients with risk factors to atherosclerosis-both as a primary and a secondary prevention. The beneficial effects observed with statin therapy are not merely related to changes in lipid profile but also are due to a positive effect on vascular inflammation and on immune-modulation of T lymphocytes and endothelial progenitor stem cells (EPCs). This dual effect has been demonstrated mainly in clinical trials where a change in endothelial function was observed within hours, much earlier than the effects of statins on the lipid profile (weeks). Based on all the knowledge that we have today questions were raised as to the mechanistic pathways that may explain the process of atherosclerosis and through this pathway to find better solutions and therapies to prevent and fight atherosclerosis. Our review will focus on the new updates in the field of inflammation and stem cells in vascular biology-in relation with atherosclerosis.

The combined effect of hypertension and type 2 diabetes mellitus on aortic stiffness and endothelial dysfunction: an integrated study with high-resolution MRI

PURPOSE

The purpose of this study was to investigate the combined effect of hypertension and type 2 diabetes mellitus (DM2) on aortic stiffness and endothelial dysfunction by using an integrated MRI approach.

MATERIALS AND METHODS

A total of 31 non-hypertensive DM2 patients and 31 hypertensive DM2 patients underwent 3.0-T MRI. Aortic distensibility (AD), pulse wave velocity (PWV) and brachial artery flow-mediated dilation (FMD) were assessed. Student's t-test, Mann-Whitney U test, chi-squared test, Pearson correlation analysis, and univariable and multiple linear regression analyses were used for statistical analyses.

RESULTS

The hypertensive patients showed lower AD at multiple levels (ascending aorta [AA]: 2.07±0.98×10(-3)mm Hg(-1) vs. 3.21±1.70×10(-3)mm Hg(-1), p<0.01; proximal thoracic descending aorta [PDA]: 2.58±0.72×10(-3)mm Hg(-1) vs. 3.58±1.47×10(-3)mm Hg(-1), p<0.01; distal descending aorta [DDA]: 3.11±1.84×10(-3)mm Hg(-1) vs. 4.27±1.75×10(-3)mm Hg(-1), p<0.01); faster PWV (7.46±2.28m/s vs. 5.82±1.12m/s, p<0.05) and lower FMD (12.67%±6.49% vs. 20.66%±9.7%; p<0.01). Systolic blood pressure was an independent predictor of PWV, AA-AD, DDA-AD and FMD. FMD was statistically significantly associated with PWV (r=-0.37, p<0.01) and AD (p<0.01).

CONCLUSIONS

Hypertension has a contributive effect on aortic stiffness and endothelial dysfunction in DM2 patients.

Endothelial dysfunction in diabetes: pathogenesis, significance, and treatment

Type 2 diabetes (T2D) markedly increases the risk of cardiovascular disease. Endothelial dysfunction (ED), an early indicator of diabetic vascular disease, is common in T2D and independently predicts cardiovascular risk. Although the precise pathogenic mechanisms for ED in T2D remain unclear, at inception they probably involve uncoupling of both endothelial nitric oxide synthase activity and mitochondrial oxidative phosphorylation, as well as the activation of vascular nicotinamide adenine dinucleotide phosphate oxidase. The major contributing factors include dyslipoproteinemia, oxidative stress, and inflammation. Therapeutic interventions are designed to target these pathophysiological factors that underlie ED. Therapeutic interventions, including lifestyle changes, antiglycemic agents and lipid-regulating therapies, aim to correct hyperglycemia and atherogenic dyslipidemia and to improve ED. However, high residual cardiovascular risk is seen in both research and clinical practice settings. Well-designed studies of endothelial function in appropriately selected volunteers afford a good opportunity to test new therapeutic interventions, paving the way for clinical trials and utilization in the care of the diabetic patient. However, based on the results from a recent clinical trial, niacin should not be added to a statin in individuals with low high-density lipoprotein cholesterol and very well controlled low-density lipoprotein cholesterol.

Arterial wall elasticity measured using the phased tracking method and atherosclerotic risk factors in patients with type 2 diabetes

AIM

The aim of this study was to investigate the relationship between atherosclerotic manifestations and brachial and radial arterial wall elasticity (AWE) measured using the phased tracking method in patients with type 2 diabetes mellitus (T2DM).

METHODS

This study included T2DM patients (n= 220, mean age 59 years) without a history of stroke or coronary artery disease. The brachial AWE, radial AWE, carotid mean intima-media thickness (IMT), max-IMT and flow-mediated vasodilation (FMD) were measured. The patients were classified according to the number of atherosclerotic risk factors, including obesity, dyslipidemia and hypertension. Group 1 included T2DM patients only, group 2 included patients with two risk factors, group 3 included patients with three risk factors and group 4 included patients with four risk factors. The patients were also divided into two groups according to microangiopathic complications, including retinopathy and nephropathy. The between-group differences were analyzed.

RESULTS

The brachial AWE (548, 697, 755 and 771 kPa for groups 1, 2, 3 and 4, respectively) and radial AWE (532, 637, 717 and 782 kPa for groups 1, 2, 3 and 4, respectively) significantly increased in association with an increasing number of risk factors. The brachial AWE and radial AWE were significantly higher in the patients with microangiopathic complications than in those without microangiopathic complications (brachial AWE 797 and 694 kPa and radial AWE 780 and 660 kPa, respectively). Receiver operating characteristic curve analyses revealed that, for brachial AWE and radial AWE, the area under the curve was equal to the max-IMT and higher than the mean-IMT and FMD.

CONCLUSIONS

Upper limb AWE measurement can reflect the degree of atherosclerosis risk overload and may be useful for evaluating vascular complications in T2DM patients.

The vascular endothelium in diabetes--a therapeutic target?

Insulin resistance affects the vascular endothelium, and contributes to systemic insulin resistance by directly impairing the actions of insulin to redistribute blood flow as part of its normal actions driving muscle glucose uptake. Impaired vascular function is a component of the insulin resistance syndrome, and is a feature of type 2 diabetes. On this basis, the vascular endothelium has emerged as a therapeutic target where the intent is to improve systemic metabolic state by improving vascular function. We review the available literature presenting studies in humans, evaluating the effects of metabolically targeted and vascular targeted therapies on insulin action and systemic metabolism. Therapies that improve systemic insulin resistance exert strong concurrent effects to improve vascular function and vascular insulin action. RAS-acting agents and statins have widely recognized beneficial effects on vascular function but have not uniformly produced the hoped-for metabolic benefits. These observations support the notion that systemic metabolic benefits can arise from therapies targeted at the endothelium, but improving vascular insulin action does not result from all treatments that improve endothelium-dependent vasodilation. A better understanding of the mechanisms of insulin's actions in the vascular wall will advance our understanding of the specificity of these responses, and allow us to better target the vasculature for metabolic benefits.

Statins for the primary prevention of cardiovascular disease

BACKGROUND

Reducing high blood cholesterol, a risk factor for cardiovascular disease (CVD) events in people with and without a past history of CVD is an important goal of pharmacotherapy. Statins are the first-choice agents. Previous reviews of the effects of statins have highlighted their benefits in people with CVD. The case for primary prevention was uncertain when the last version of this review was published (2011) and in light of new data an update of this review is required.

OBJECTIVES

To assess the effects, both harms and benefits, of statins in people with no history of CVD.

SEARCH METHODS

To avoid duplication of effort, we checked reference lists of previous systematic reviews. The searches conducted in 2007 were updated in January 2012. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2022, Issue 4), MEDLINE OVID (1950 to December Week 4 2011) and EMBASE OVID (1980 to 2012 Week 1).There were no language restrictions.

SELECTION CRITERIA

We included randomised controlled trials of statins versus placebo or usual care control with minimum treatment duration of one year and follow-up of six months, in adults with no restrictions on total, low density lipoprotein (LDL) or high density lipoprotein (HDL) cholesterol levels, and where 10% or less had a history of CVD.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion and extracted data. Outcomes included all-cause mortality, fatal and non-fatal CHD, CVD and stroke events, combined endpoints (fatal and non-fatal CHD, CVD and stroke events), revascularisation, change in total and LDL cholesterol concentrations, adverse events, quality of life and costs. Odds ratios (OR) and risk ratios (RR) were calculated for dichotomous data, and for continuous data, pooled mean differences (MD) (with 95% confidence intervals (CI)) were calculated. We contacted trial authors to obtain missing data.

MAIN RESULTS

The latest search found four new trials and updated follow-up data on three trials included in the original review. Eighteen randomised control trials (19 trial arms; 56,934 participants) were included. Fourteen trials recruited patients with specific conditions (raised lipids, diabetes, hypertension, microalbuminuria). All-cause mortality was reduced by statins (OR 0.86, 95% CI 0.79 to 0.94); as was combined fatal and non-fatal CVD RR 0.75 (95% CI 0.70 to 0.81), combined fatal and non-fatal CHD events RR 0.73 (95% CI 0.67 to 0.80) and combined fatal and non-fatal stroke (RR 0.78, 95% CI 0.68 to 0.89). Reduction of revascularisation rates (RR 0.62, 95% CI 0.54 to 0.72) was also seen. Total cholesterol and LDL cholesterol were reduced in all trials but there was evidence of heterogeneity of effects. There was no evidence of any serious harm caused by statin prescription. Evidence available to date showed that primary prevention with statins is likely to be cost-effective and may improve patient quality of life. Recent findings from the Cholesterol Treatment Trialists study using individual patient data meta-analysis indicate that these benefits are similar in people at lower (< 1% per year) risk of a major cardiovascular event.

AUTHORS' CONCLUSIONS

Reductions in all-cause mortality, major vascular events and revascularisations were found with no excess of adverse events among people without evidence of CVD treated with statins.

Determinants of vascular function in patients with type 2 diabetes

Background

Type 2 diabetes mellitus (T2DM) is independently associated with an increased risk for cardiovascular diseases that is primarily due to the early development of advanced atherosclerotic vascular changes. The aim of our study was to investigate the predictors of vascular dysfunction in T2DM patients.

Methods

We studied 165 T2DM patients without known macrovascular or microvascular disease. Standard demographic (age, gender, cardiovascular risk factors, medications), clinical (body mass index, blood pressure) and laboratory (glucose, glycated hemoglobin, lipids, renal function) parameters were included in analyses. Brachial artery flow-mediated dilation (FMD), nitrate mediated dilation (NMD) and Carotid-Femoral Pulse Wave Velocity (PWV) were measured.

Results

Median age was 66 years and duration since T2DM diagnosis was 10 years, 70% were females and 79% hypertensives, while only 10% had a glycated hemoglobin <7%. FMD was positively associated with NMD (r 0.391, P < 0.001), while PWV was inversely associated with FMD (r -0.218, P = 0.014) and NMD (r -0.309, P < 0.001). Time since diagnosis of diabetes was the single independent predictor of FMD (β -0.40, P = 0.003). Increased age and fasting glucose and the presence of hypertension were independent predictors of decreased NMD (P < 0.001). Increased age and systolic blood pressure were independently associated with increased PWV (P < 0.001).

Conclusions

In T2DM patients, impairment of endothelium-dependent vasodilation was independently associated only with longer diabetes duration while no association with other established risk factors was found. Vascular smooth muscle dysfunction and increased arterial stiffness were more prominent in older T2DM patients with hypertension. Worse glycemic control was associated with impaired vascular smooth muscle function.

Ultrasound measurement of peripheral endothelial dysfunction in type 2 diabetic patients: correlation with risk factors

The purpose of the study was to assess the endothelial dysfunction (ED) in type 2 diabetic patients ultrasonographically and estimate the correlation of ED with glycemia and other cardio-metabolic risk factors. 171 patient (age 60.0 + 8.5 years) with diagnosed type 2 diabetes and coronary artery disease (CAD) were randomly included in a cross sectional study. B-mode ultrasound system with a linear transducer of 7.5 MHz was used for evaluation of flow-mediated vasodilation in brachial artery (FMV). FMV was presented as a change of brachial artery diameter at rest and after limb ischemia, previously provoked by cuff inflation. Peripheral ED was found in 77.2% (132 patients). Multivariate logistic regression model defined: age (OR 1.071, 95% CI 1.003 1,143) and plasma cholesterol (OR 4.083 95% CI 1.080 17,017) as determinants for ED. Linear multivariate analysis presented duration of diabetes (Beta 0.173, Sig 0.024), and glycemia (Beta 0.132, Sig 0.044) to be associated independently with FMV value. Estimated factors influencing FMV, might be potential therapeutic targets for presented endothelial dysfunction in type 2 diabetic patients with coronary artery disease.

Low-dose statin therapy improves endothelial function in type 2 diabetic patients with normal serum total cholesterol: a randomized placebo-controlled study

The authors sought to explore the effect of low-dose atorvastatin on endothelial function in normocholesterolemic patients with type 2 diabetes mellitus without evidence of coronary disease. Sixty patients with type 2 diabetes mellitus, normal serum cholesterol, and normal exercise test results were enrolled. Initial assessment was performed by measurement of the brachial artery diameter and flow velocity both at baseline and after induced hyperemia. Patients were randomly assigned to receive either atorvastatin 10 mg daily for 4 weeks (atorvastatin group=30 patients) or matched placebo for the same period (placebo group=30 patients). Follow-up assessment of the brachial artery diameter and flow velocity (both baseline and hyperemic) was performed after 4 weeks. Initially, no significant difference was found between the two groups regarding brachial artery diameter or flow velocity, both at baseline and at peak hyperemia (P>.05 for all). At follow-up, there was a significantly higher flow velocity at baseline (P<.05) and a significantly higher percent increase of brachial artery diameter (from baseline to peak hyperemia) in the atorvastatin group (P<.05). In patients with type 2 diabetes mellitus and normal serum cholesterol without evidence of coronary disease, low-dose atorvastatin improves endothelial function.

Reviewing statin therapy in diabetes--towards the best practise

Statin therapy is considered critical both in primary and secondary prevention of cardiovascular disease in diabetes. Cholesterol Treatment Trialists' Collaborators meta-analysis of 14 randomised trials of statins in 18686 people with diabetes provides the latest and largest evidence showing a significant 21% reduction in major vascular events per mmol/l reduction in LDL cholesterol. Importantly, the risk reduction was similar in both types of diabetes. Growing evidence supports the view that statin therapy reduces microvascular complications as well. This review updates the current knowledge of statin therapy in preventing micro- and macrovascular complications in both type 1 and type 2 diabetes.

Effects of contrast baths on skin blood flow on the dorsal and plantar foot in people with type 2 diabetes and age-matched controls

Contrast baths have been used for therapy for over 2,000 years. The basic concept is to alternate warm and cool water baths during a treatment session. It is believed that this will increase circulation better than just placing the limb in a warm water bath. However, there is little supportive evidence for this assertion. Further, for subjects with diabetes, with underlying impairments in their circulation, this may not work at all. Fourteen people with type 2 diabetes were compared to 14 age-matched controls. Skin blood flow of the foot (BF) was measured during 16 minutes of contrast baths at two different intervals: 3 minutes warm and 1 minute cold and 6 minutes warm and 2 minutes cold. In control subjects, warm and cold contrast baths with the ratio 3 minutes warm to 1 minute cold elicited significantly (p < 0.01) greater BF than placing the limb continuously in warm water or using a 6:2 ratio of warm to cold bath time. In control subjects, there was also a greater plantar than dorsal BF. For subjects with diabetes, there was no statistical difference between BF with contrast baths versus warm whirlpool; but in both cases BF was significantly less than that seen in control subjects under similar circumstances. There was also very little difference between BF on the plantar and dorsal aspects of the foot in the subjects with diabetes. Patients with diabetes do not show a vascular response to contrast bath therapy. The BF response to contrast temperatures may be a good diagnostic test for diabetic vascular impairment.

Novel approaches to improving endothelium-dependent nitric oxide-mediated vasodilatation

Endothelial dysfunction, which is defined by decreased endothelium-dependent vasodilatation, is associated with an increased number of cardiovascular events. Nitric oxide (NO) bioavailability is reduced by altered endothelial signal transduction or increased formation of radical oxygen species reacting with NO. Endothelial dysfunction is therapeutically reversible and physical exercise, calcium channel blockers, angiotensin converting enzyme inhibitors, and angiotensin receptor antagonists improve flow-evoked endothelium-dependent vasodilation in patients with hypertension and diabetes. We have investigated three different approaches, with the aim of correcting endothelial dysfunction in cardiovascular disease. Thus, (1) we evaluated the effect of a cell permeable superoxide dismutase mimetic, tempol, on endothelial dysfunction in small arteries exposed to high pressure, (2) investigated the endothelial signal transduction pathways involved in vasorelaxation and NO release induced by an olive oil component, oleanolic acid, and (3) investigated the role of calcium-activated K channels in the release of NO induced by receptor activation. Tempol increases endothelium-dependent vasodilatation in arteries from hypertensive animals most likely through the lowering of radical oxygen species, but other mechanisms also appear to contribute to the effect. While oleanolic acid leads to the release of NO by calcium-independent phosphorylation of endothelial NO synthase, endothelial calcium-activated K channels and an influx of calcium play an important role in G-protein coupled receptor-evoked release of NO. Thus, all three approaches increase bioavailability of NO in the vascular wall, but it remains to be addressed whether these actions have any direct benefit at a clinical level.

Placebo-Controlled Trial of High-Dose Atorvastatin in Patients With Severe Cerebral Small Vessel Disease

Background and Purpose— Uncontrolled studies have shown that statins can improve cerebral vasoreactivity (CVR) in patients with mild small vessel disease. We sought to determine whether high-dose atorvastatin increases CVR compared with placebo in patients with severe small vessel disease.

Methods— Ninety-four adults with recent lacunar stroke were randomly allocated in a double-blind manner to 80 mg of atorvastatin daily or matching placebo after stratification for hypertensive and diabetic status. The primary end point was change in CVR after 3 months of treatment. Secondary outcomes were changes in brachial and carotid artery endothelial-dependent vasodilations.

Results— At baseline, all patients had a severely impaired CVR (mean, 12.1%; 95% CI, 9.5–14.7) and carotid (mean, −0.25%; 95% CI, −1.17–0.67) and brachial artery (mean, 2.72%; 95% CI, 1.39–4.05) endothelial function. Despite reductions of 55% in low-density lipoprotein cholesterol and of 30% in high-sensitivity C-reactive protein in the active arm compared to placebo, atorvastatin 80 mg per day did not improve CVR or endothelial dysfunction of carotid and brachial arteries.

Conclusion— We found no positive effect of 3-month treatment with atorvastatin on severe cerebral microvasculature endothelial dysfunction in patients with lacunar stroke.

Short term effects of atorvastatin on endothelial functions and oxidized LDL levels in patients with type 2 diabetes

OBJECTIVE

This study was designed in order to investigate the short term effects of atorvastatin on endothelial function and oxidized LDL (oxLDL) levels and to evaluate the association of endothelial dysfunction to oxLDL levels and inflammatory markers in type 2 diabetic patients.

MATERIAL AND METHODS

Thirty type 2 diabetic and 11 healthy subjects with LDL levels between 100-160 mg/dl. without a history of cardiovascular event were included in the study. Both groups were matched with respect to age, gender, body mass indices and lipid levels. Flow- mediated dilatation (endothelium dependent, FMD) and nitroglycerine-induced dilatation (endothelium independent, NID) were measured in the brachial artery using high-resolution ultrasound in all participants and carotid artery intima media thickness (IMT) were also evaluated. OxLDL levels, lipid parameters, blood glucose, C-peptide, HbA1c and inflammatory markers including C-reactive protein (CRP), fibrinogen, erythrocyte sedimentation rate (ESR) were studied. Type 2 diabetic patients received 10 mg. Atorvastatin for 6 weeks and FMD and NID were reevaluated and oxLDL levels and inflammatory markers remeasured.

RESULTS

Basal FMD, NID, IMT and oxLDL levels besides inflammatory markers were not significantly different between patients and controls. No correlation was found between inflammatory markers and FMD and NID. Only IMT correlated with fibrinogen levels obtained before treatment. In non-diabetics, IMT also correlated with oxLDL levels (p: 0.013). FMD and NID significantly improved after atorvastatin therapy ((7.62 +/- 7.6 vs. 12.65 +/- 7.8, p<0.001 and 18.22 +/- 9.57 vs. 21.43 +/- 9.6, p: 0.007, respectively). Atorvastatin significantly reduced oxLDL levels (57.85 +/- 10.33 vs. 44.36 +/- 6.34, p<0.001).

CONCLUSION

Atorvastatin improves endothelial functions and reduces oxLDL levels in type 2 diabetics with average lipid levels in the short term and may have beneficial effects in the prevention of early atherosclerotic changes.

Endothelial dysfunction: from molecular mechanisms to measurement, clinical implications, and therapeutic opportunities

Endothelial dysfunction has been implicated as a key factor in the development of a wide range of cardiovascular diseases, but its definition and mechanisms vary greatly between different disease processes. This review combines evidence from cell-culture experiments, in vitro and in vivo animal models, and clinical studies to identify the variety of mechanisms involved in endothelial dysfunction in its broadest sense. Several prominent disease states, including hypertension, heart failure, and atherosclerosis, are used to illustrate the different manifestations of endothelial dysfunction and to establish its clinical implications in the context of the range of mechanisms involved in its development. The size of the literature relating to this subject precludes a comprehensive survey; this review aims to cover the key elements of endothelial dysfunction in cardiovascular disease and to highlight the importance of the process across many different conditions.

Sustained benefits in vascular function through flavanol-containing cocoa in medicated diabetic patients a double-masked, randomized, controlled trial

OBJECTIVES

Our goal was to test feasibility and efficacy of a dietary intervention based on daily intake of flavanol-containing cocoa for improving vascular function of medicated diabetic patients.

BACKGROUND

Even in fully medicated diabetic patients, overall prognosis is unfavorable due to deteriorated cardiovascular function. Based on epidemiological data, diets rich in flavanols are associated with a reduced cardiovascular risk.

METHODS

In a feasibility study with 10 diabetic patients, we assessed vascular function as flow-mediated dilation (FMD) of the brachial artery, plasma levels of flavanol metabolites, and tolerability after an acute, single-dose ingestion of cocoa, containing increasing concentrations of flavanols (75, 371, and 963 mg). In a subsequent efficacy study, changes in vascular function in 41 medicated diabetic patients were assessed after a 30-day, thrice-daily dietary intervention with either flavanol-rich cocoa (321 mg flavanols per dose) or a nutrient-matched control (25 mg flavanols per dose). Both studies were undertaken in a randomized, double-masked fashion. Primary and secondary outcome measures included changes in FMD and plasma flavanol metabolites, respectively.

RESULTS

A single ingestion of flavanol-containing cocoa was dose-dependently associated with significant acute increases in circulating flavanols and FMD (at 2 h: from 3.7 +/- 0.2% to 5.5 +/- 0.4%, p < 0.001). A 30-day, thrice-daily consumption of flavanol-containing cocoa increased baseline FMD by 30% (p < 0.0001), while acute increases of FMD upon ingestion of flavanol-containing cocoa continued to be manifest throughout the study. Treatment was well tolerated without evidence of tachyphylaxia. Endothelium-independent responses, blood pressure, heart rate, and glycemic control were unaffected.

CONCLUSIONS

Diets rich in flavanols reverse vascular dysfunction in diabetes, highlighting therapeutic potentials in cardiovascular disease.

Reduction in blood pressure with statins: results from the UCSD Statin Study, a randomized trial

BACKGROUND

Some studies have suggested reductions in blood pressure (BP)with statin treatment, particularly in persons with hypertension. Randomized trial evidence is limited.

METHODS

We performed a randomized, double-blind, placebo-controlled trial with equal allocation to simvastatin, 20 mg; pravastatin sodium,40 mg; or placebo for 6 months. Nine hundred seventy-three men and women without known cardiovascular disease or diabetes mellitus, with low-density lipoprotein cholesterol screening levels of 115 to 190 mg/dL, had assessment of systolic and diastolic BP (SBP and DBP, respectively). Blood pressure values were compared for placebo vs statins by intention-to-treat (ITT) analysis. Additional analyses were performed that (1) were confined to subjects with neither high baseline BP (SBP>140 mm Hg or DBP>90 mm Hg) nor receiving BP medications, to exclude groups in whom BP medications or medication changes may have influenced results, and (2) separately evaluated simvastatin and pravastatin (vs placebo). The time course of BP changes after statin initiation and the effect of stopping statins on BP were examined.

RESULTS

Statins modestly but significantly reduced BP relative to placebo,by 2.2 mm Hg for SBP (P=.02) and 2.4 mm Hg for DBP (P<.001) in ITT analysis. Blood pressure reductions ranged from 2.4 to 2.8 mm Hg for both SBP and DBP with both simvastatin and pravastatin, in those subjects with full follow-up, and without potential for influence by BP medications (ie, neither receiving nor meriting BP medications).

CONCLUSIONS

Reductions in SBP and DBP occurred with hydrophilic and lipophilic statins and extended to normotensive subjects. These modest effects may contribute to the reduced risk of stroke and cardiovascular events reported on statins. Trial Registration clinicaltrials.gov Identifier: NCT00330980.

The impact of metabolic syndrome and CRP on vascular phenotype in type 2 diabetes mellitus

BACKGROUND

The burden of cardiovascular disease in diabetes mellitus type 2 (DM2) patients is variable. We hypothesize that metabolic syndrome (MS) and low-grade systemic inflammation modify the extent of atherosclerosis in DM2.

METHODS

Vascular phenotype was determined using the following endothelium-related, hemostatic, and sonographic endpoints in 62 DM2 patients with mild dyslipidemia: sVCAM, sE-selectin, von Willebrand factor (VWF), fibrinogen, s-thrombomodulin (sTM), tPA, PAI-1, flow-mediated dilation (FMD), and intima media thickness (IMT). The impact of MS load (number of criteria present), MS components, and CRP on these parameters was assessed.

RESULTS

Serum sVCAM, sTM, and tPA levels significantly increased with increasing MS load. IMT also significantly increased from 0.602+/-0.034 (one MS criterion) to 0.843+/-0.145 (four MS criteria, p=0.007). LogCRP significantly correlated with fibrinogen, PAI-1, and IMT. In a multiple regression (MR) model with age and gender as covariates, MS load predicted sVCAM and sTM; CRP predicted PAI-1 and fibrinogen; MS load and CRP simultaneously predicted tPA and IMT. For each MS criterion present, IMT significantly increased by 0.04 mm. An increase in CRP from 1 to 3 mg/L resulted in a significant increase of 0.04 mm. Patients with four MS criteria and inflammation (CRP >or=3 mg/L) are predicted to have a 0.21 mm thicker IMT than those without. A second stepwise MR analysis based on gender, traditional risk factors, diabetes-related parameters, renal function, individual MS criteria, and LogCRP as explanatory variables showed a significant effect of systolic and diastolic blood pressure, HDL, and LogCRP on IMT(r(2)=0.36, p<0.001).

CONCLUSION

MS and low-grade chronic inflammation have an independent impact on vascular phenotype including IMT in DM2.

Endothelial dysfunction in diabetes mellitus

Diabetes mellitus is associated with an increased risk of cardiovascular disease, even in the presence of intensive glycemic control. Substantial clinical and experimental evidence suggest that both diabetes and insulin resistance cause a combination of endothelial dysfunctions, which may diminish the anti-atherogenic role of the vascular endothelium. Both insulin resistance and endothelial dysfunction appear to precede the development of overt hyperglycemia in patients with type 2 diabetes. Therefore, in patients with diabetes or insulin resistance, endothelial dysfunction may be a critical early target for preventing atherosclerosis and cardiovascular disease. Microalbuminuria is now considered to be an atherosclerotic risk factor and predicts future cardiovascular disease risk in diabetic patients, in elderly patients, as well as in the general population. It has been implicated as an independent risk factor for cardiovascular disease and premature cardiovascular mortality for patients with type 1 and type 2 diabetes mellitus, as well as for patients with essential hypertension. A complete biochemical understanding of the mechanisms by which hyperglycemia causes vascular functional and structural changes associated with the diabetic milieu still eludes us. In recent years, the numerous biochemical and metabolic pathways postulated to have a causal role in the pathogenesis of diabetic vascular disease have been distilled into several unifying hypotheses. The role of chronic hyperglycemia in the development of diabetic microvascular complications and in neuropathy has been clearly established. However, the biochemical or cellular links between elevated blood glucose levels, and the vascular lesions remain incompletely understood. A number of trials have demonstrated that statins therapy as well as angiotensin converting enzyme inhibitors is associated with improvements in endothelial function in diabetes. Although antioxidants provide short-term improvement of endothelial function in humans, all studies of the effectiveness of preventive antioxidant therapy have been disappointing. Control of hyperglycemia thus remains the best way to improve endothelial function and to prevent atherosclerosis and other cardiovascular complications of diabetes. In the present review we provide the up to date details on this subject.

Is assessment of peripheral endothelial dysfunction useful tool for risk stratification of type 2 diabetic patients with manifested coronary artery disease?

Endothelial dysfunction, per se, in coronary arteries can stratify a risk in coronary artery disease patients. Selected studies evaluating endotheliopathy as predictor of events in patients with type 2 diabetes, but without coronary artery disease. We hypothesized that peripheral endothelial dysfunction could predict prognosis of type 2 diabetic patients who presented coronary artery disease. Our data presented endothelial dysfunction as prognostic marker of cardiovascular events in type 2 diabetic patients with manifested coronary artery disease, according univariate regression model.

Vascular phenotype and subclinical inflammation in diabetic Asian Indians without overt cardiovascular disease

Although Asian Indian (AI) patients with diabetes mellitus type 2 (DM2) are at high risk for cardiovascular disease (CVD), not all patients develop CVD. The vascular phenotype of AI-DM2 without CVD has not been elucidated and may point to protective features. Using baseline data from a clinical trial we provide an initial description of vascular parameters in AI-DM2 compared to Europid Caucasian controls (ECs) matched for age and gender. Endpoints of the study were endothelial function, low-grade systemic inflammation (CRP) and carotid intima-media thickness (cIMT). AIs had longer duration of diabetes, worse glycemic control and more microangiopathy. Both groups demonstrated marked endothelial dysfunction. CRP levels were similar: 1.7 (4.9) mg/L in AIs and 2.8 (3.6) mg/L in ECs. cIMT values were significantly lower in AI-DM2 than EC-DM2 (0.655mm (0.12) versus 0.711mm (0.15), p=0.03). Multiple regression analysis showed that variability in CRP was mainly determined by waist circumference, not by ethnicity. In contrast, ethnicity was a significantly explanatory variable for cIMT. Vascular phenotype of AI-DM2 without CVD was characterized by endothelial dysfunction and relatively low levels of CRP, comparable to EC-DM2 controls. In contrast, lower cIMT values were observed in AI-DM2 despite longer duration of diabetes and worse metabolic control. We propose that mechanisms slowing its progression may have atheroprotective potential in AI-DM2.

Therapeutic regulation of endothelial dysfunction in type 2 diabetes mellitus

Endothelial dysfunction is universal in diabetes, being intimately involved with the development of cardiovascular disease. The pathogenesis of endothelial dysfunction in diabetes is complex. It is initially related to the effects of fatty acids and insulin resistance on 'uncoupling' of both endothelial nitric oxide synthase activity and mitochondrial function. Oxidative stress activates protein kinase C (PKC), polyol, hexosamine and nuclear factor kappa B pathways, thereby aggravating endothelial dysfunction. Improvements in endothelial function in the peripheral circulation in diabetes have been demonstrated with monotherapies, including statins, fibrates, angiotensin-converting enzyme (ACE) inhibitors, metformin and fish oils. These observations are supported by large clinical end point trials. Other studies show benefits with certain antioxidants, L-arginine, folate, PKC-inhibitors, peroxisome proliferator activated receptor (PPAR)-alpha and -gamma agonists and phosphodiesterase (PDE-5) inhibitors. However, the benefits of these agents remain to be shown in clinical end point trials. Combination treatments, for example, statins plus ACE inhibitors and statins plus fibrates, have also been demonstrated to have additive benefits on endothelial function in diabetes, but there are no clinical outcome data to date. Measurement of endothelial dysfunction in cardiovascular research can provide fresh opportunities for exploring the mechanism of benefit of new therapeutic regimens and for planning and designing large clinical trials.

Mechanisms of Disease: endothelial dysfunction in insulin resistance and diabetes

Endothelial dysfunction is one manifestation of the many changes induced in the arterial wall by the metabolic abnormalities accompanying diabetes and insulin resistance. In type 1 diabetes, endothelial dysfunction is most consistently found in advanced stages of the disease. In other patients, it is associated with nondiabetic insulin resistance and probably precedes type 2 diabetes. In obesity and insulin resistance, increased secretion of proinflammatory cytokines and decreased secretion of adiponectin from adipose tissue, increased circulating levels of free fatty acids, and postprandial hyperglycemia can all alter gene expression and cell signaling in vascular endothelium, cause vascular insulin resistance, and change the release of endothelium-derived factors. In diabetes, sustained hyperglycemia causes increased intracellular concentrations of glucose metabolites in endothelial cells. These changes cause mitochondrial dysfunction, increased oxidative stress, and activation of protein kinase C. Dysfunctional endothelium displays activation of vascular NADPH oxidase, uncoupling of endothelial nitric oxide synthase, increased expression of endothelin 1, a changed balance between the production of vasodilator and vasoconstrictor prostanoids, and induction of adhesion molecules. This review describes how these and other changes influence endothelium-dependent vasodilation in patients with insulin resistance and diabetes. The clinical utility of endothelial function testing and future therapeutic targets is also discussed.

Atorvastatin normalizes endothelial function in healthy smokers

Endothelial function is known to predict cardiovascular disease. The aim of the present study was to examine whether endothelial function in smokers with normal cholesterol levels could be normalized by treatment with 80 mg of atorvastatin in comparison with a control group. Healthy smokers (n=20) and non-smokers (n=20) were randomized to receive 80 mg of atorvastatin or placebo in an open randomized cross-over study, followed by measurement of endothelial functional [FMD (flow-mediated dilation)]. At baseline, smokers had a lower FMD compared with the non-smoking group (2.2+/-0.5 and 4.5+/-0.8% respectively; P<0.05). In the smoking group, FMD increased significantly (P<0.05) to 4.0+/-0.8% during treatment with atorvastatin and returned to basal levels during placebo (2.3+/-0.6%). In the non-smoking group, FMD was unaffected by both atorvastatin and placebo. The net change of total cholesterol or LDL (low-density lipoprotein)-cholesterol was not associated with the net change in FMD when the study group was considered as a whole or the smoking group was considered separately. In conclusion, improved endothelial function was observed in a group of smokers when they were received 80 mg of atorvastatin, whereas atorvastatin had no effect on endothelial function in the non-smoking group. The improved FMD among smokers was independent of the decrease in LDL-cholesterol during atorvastatin treatment. The results show that poor endothelial function in smokers with normal lipid levels can be improved by a statin treatment.