Long-term pioglitazone therapy improves arterial stiffness in patients with type 2 diabetes mellitus

Associations between continuous glucose monitoring-derived metrics and arterial stiffness in Japanese patients with type 2 diabetes

BACKGROUND

Previous studies have suggested that high mean glucose levels and glycemic abnormalities such as glucose fluctuation and hypoglycemia accelerate the progression of atherosclerosis in patients with type 2 diabetes. Although continuous glucose monitoring (CGM) that could evaluate such glycemic abnormalities has been rapidly adopted, the associations between CGM-derived metrics and arterial stiffness are not entirely clear.

METHODS

This exploratory cross-sectional study used baseline data from an ongoing prospective, multicenter, observational study with 5 years of follow-up. Study participants included 445 outpatients with type 2 diabetes and no history of apparent cardiovascular disease who underwent CGM and brachial-ankle pulse wave velocity (baPWV) measurement at baseline. Associations between CGM-derived metrics and baPWV were analyzed using multivariate regression models.

RESULTS

In a linear regression model, all CGM-derived metrics were significantly associated with baPWV, but HbA1c was not. Some CGM-derived metrics related to intra-day glucose variability, hyperglycemia, and hypoglycemia remained significantly associated with baPWV after adjusting for possible atherosclerotic risk factors, including HbA1c. Based on baPWV ≥ 1800 cm/s as indicative of high arterial stiffness, multivariate logistic regression found that some CGM-derived metrics related to intra-day glucose variability and hyperglycemia are significantly associated with high arterial stiffness even after adjusting for possible atherosclerotic risk factors, including HbA1c.

CONCLUSIONS

Multiple CGM-derived metrics are significantly associated with baPWV and high arterial stiffness in patients with type 2 diabetes who have no history of apparent cardiovascular disease. These metrics might be useful for identifying patients at high risk of developing cardiovascular disease.

Prognostic value of arterial stiffness measurements in cardiovascular disease, diabetes, and its complications: The potential role of sodium-glucose co-transporter-2 inhibitors

Type 2 diabetes mellitus (T2DM) constitutes a global pandemic, representing the 7th cause of death worldwide. Morbidity and mortality of patients with T2DM are gradually increasing, while prevalence of cardiovascular disease (CVD) among these patients is almost 14% greater compared to the general population. Arterial stiffness is nowadays a valuable biomarker of CVD and a promising treatment target in specific patient groups, including those suffering from T2DM. Despite that fact, design of the available studies cannot prove causal relationship. Recently, a new antidiabetic drug class, namely sodium-glucose co-transporter-2 (SGLT-2) inhibitors, has attracted scientific interest, due to their multiple, beneficial, pleiotropic effects, especially those focused on CVD. There is limited relevant literature concerning the effects of SGLT-2 inhibitors on arterial stiffness, while retrieved results might be considered as conflicting. The aim of the present review article is to summarize acquired knowledge regarding the prognostic role of arterial stiffness in T2DM, along with the presentation of retrieved data on the potential role of SGLT-2 inhibitors.

MitoNEET in Perivascular Adipose Tissue Prevents Arterial Stiffness in Aging Mice

PURPOSE

Arterial stiffness is an inevitable consequence of the aging process and is considered an early stage in the development of cardiovascular diseases. The perivascular adipose tissue (PVAT) is a distinct functional integral layer of the vasculature actively involved in blood pressure regulation and atherosclerosis development via PVAT-derived paracrine/autocrine factors. However, there is little knowledge regarding the relationship between PVAT and arterial stiffness.

METHODS

Using unique mice lacking PVAT, high-fat diet-induced obesity, and in mice overexpressing brown adipocyte selective mitoNEET, we investigated the relationship between PVAT and arterial stiffness in mice.

RESULTS

We found that lack of PVAT enhanced arterial stiffness in aging mice. High-fat diet feeding of aging C57BL/6J wild-type mice significantly induced hypertrophic PVAT and enhanced arterial stiffness. Furthermore, the expression of mitoNEET, a mitochondrial membrane protein related to energy expenditure, was significantly increased by pioglitazone treatment, while reduced in the hypertrophic PVAT induced by high-fat diet. Overexpression of mitoNEET in PVAT reduced the expression of inflammatory genes and was associated with lower pulse wave velocity in aging mice.

CONCLUSIONS

These data indicate that local PVAT homeostasis especially inflammation in PVAT is associated with arterial stiffness development. Pioglitazone-induced mitoNEET in PVAT prevents PVAT inflammation and is negatively associated with arterial stiffness. These findings provide new experimental insight into the roles of pioglitazone on PVAT in arterial stiffness and indicate that PVAT might be a target to treat or prevent cardiovascular disease.

MitoNEET in Perivascular Adipose Tissue Blunts Atherosclerosis under Mild Cold Condition in Mice

Background: Perivascular adipose tissue (PVAT), which surrounds most vessels, is de facto a distinct functional vascular layer actively contributing to vascular function and dysfunction. PVAT contributes to aortic remodeling by producing and releasing a large number of undetermined or less characterized factors that could target endothelial cells and vascular smooth muscle cells, and herein contribute to the maintenance of vessel homeostasis. Loss of PVAT in mice enhances atherosclerosis, but a causal relationship between PVAT and atherosclerosis and the possible underlying mechanisms remain to be addressed. The CDGSH iron sulfur domain 1 protein (referred to as mitoNEET), a mitochondrial outer membrane protein, regulates oxidative capacity and adipose tissue browning. The roles of mitoNEET in PVAT, especially in the development of atherosclerosis, are unknown.

Methods: The brown adipocyte-specific mitoNEET transgenic mice were subjected to cold environmental stimulus. The metabolic rates and PVAT-dependent thermogenesis were investigated. Additionally, the brown adipocyte-specific mitoNEET transgenic mice were cross-bred with ApoE knockout mice. The ensuing mice were subsequently subjected to cold environmental stimulus and high cholesterol diet challenge for 3 months. The development of atherosclerosis was investigated.

Results: Our data show that mitoNEET mRNA was downregulated in PVAT of both peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Pgc1α)- and beta (Pgc1β)-knockout mice which are sensitive to cold. MitoNEET expression was higher in PVAT of wild type mice and increased upon cold stimulus. Transgenic mice with overexpression of mitoNEET in PVAT were cold resistant, and showed increased expression of thermogenic genes. ApoE knockout mice with mitoNEET overexpression in PVAT showed significant downregulation of inflammatory genes and showed reduced atherosclerosis development upon high fat diet feeding when kept in a 16°C environment.

Conclusion: mitoNEET in PVAT is associated with PVAT-dependent thermogenesis and prevents atherosclerosis development. The results of this study provide new insights on PVAT and mitoNEET biology and atherosclerosis in cardiovascular diseases.

Do Advanced Glycation End Products and Its Receptor Play a Role in Pathophysiology of Hypertension?

There is a close relationship between arterial stiffness and blood pressure. The studies suggest that the advanced glycation end products (AGEs) and its cell receptor (RAGE) are involved in the arterial stiffness in two ways: changes in arterial structure and vascular function. Plasma levels of AGEs and expression of RAGE are elevated, while the levels of soluble RAGE (sRAGE) and endogenous secretory RAGE (esRAGE) are lowered in patients with hypertension (HTN). There is a positive correlation between plasma levels of AGEs and arterial stiffness, and an inverse association between arterial stiffness/HTN, and serum levels of sRAGE and esRAGE. Various measures can reduce the levels of AGEs and expression of RAGE, and elevate sRAGE. Arterial stiffness and blood pressure could be reduced by lowering the serum levels of AGEs, and increasing the levels of sRAGE. Levels of AGEs can be lowered by reducing the consumption of AGE-rich diet, short duration of cooking in moist heat at low temperature, and cessation of cigarette smoking. Drugs such as aminoguanidine, vitamins, angiotensin-converting enzyme (ACE) inhibitors, angiotensin-II receptor blockers, statins, and metformin inhibit AGE formation. Alagebrium, an AGE breakers reduces levels of AGEs. Clinical trials with some drugs tend to reduce stiffness. Systemic administration of sRAGE has beneficial effect in animal studies. In conclusion, AGE-RAGE axis is involved in arterial stiffness and HTN. The studies suggest that inhibition of AGEs formation, reduction of AGE consumption, blockade of AGE-RAGE interaction, suppression of RAGE expression, and exogenous administration of sRAGE may be novel therapeutic strategies for treatment of arterial stiffness and HTN.

Therapeutic Modulation of Aortic Stiffness

Aortic stiffness (AS) is an important predictor of cardiovascular morbidity in humans. The present review discusses the possible pathophysiological mechanisms of AS and focuses on a survey of different therapeutic modalities for decreasing AS. The influence of several nonpharmacological interventions is described: decrease body weight, diet, aerobic exercise training, music, and continuous positive airway pressure therapy. The effects of different pharmacological drug classes on AS are also discussed: antihypertensive drugs-renin-angiotensin-aldosterone system drugs, beta-blockers, alpha-blockers, diuretics, and calcium channel blockers (CCBs)-advanced glycation end product cross-link breakers, statins, oral anti-diabetics, anti-inflammatory drugs, vitamin D, antioxidant vitamins, and endothelin-1 receptor antagonists. All of these have shown some effect in decreasing AS.

Reversing vascular dysfunction in rheumatoid arthritis: improved augmentation index but not endothelial function with peroxisome proliferator-activated receptor γ agonist therapy

OBJECTIVE

To examine the hypothesis that improving insulin sensitivity improves vascular function in rheumatoid arthritis (RA).

METHODS

We performed a 20-week, single center, randomized, double-blind, placebo-controlled crossover study. Patients with RA (n = 34) with moderate disease activity who were receiving stable disease-modifying antirheumatic drug therapy were randomized to drug sequence, receiving either pioglitazone 45 mg/day or matching placebo for 8 weeks, followed by a 4-week washout period and the alternative treatment for 8 weeks. We measured changes in vascular stiffness (augmentation index and aortic pulse wave velocity [PWV]), endothelial function (reactive hyperemia index), and blood pressure. High-sensitivity C-reactive protein levels and the homeostatic model assessment of insulin resistance were also measured. The treatment effect of pioglitazone on outcomes was analyzed using linear mixed-effects models.

RESULTS

Pioglitazone treatment resulted in a change in augmentation index of -4.7% units (95% confidence interval [95% CI] -7.9, -1.5) (P = 0.004) and in diastolic blood pressure of -3.0 mm Hg (95% CI -5.7, -0.2) (P = 0.03), but did not significantly change aortic PWV (P = 0.33) or reactive hyperemia index (P = 0.46). The improvements in augmentation index and diastolic blood pressure were not mediated by the effect of pioglitazone on insulin resistance or inflammation.

CONCLUSION

Our findings indicate that pioglitazone improves some indices of vascular function, including augmentation index and diastolic blood pressure, in patients with RA. This is not mediated by improved insulin sensitivity.

Arterial stiffness and cardiovascular therapy

The world population is aging and the number of old people is continuously increasing. Arterial structure and function change with age, progressively leading to arterial stiffening. Arterial stiffness is best characterized by measurement of pulse wave velocity (PWV), which is its surrogate marker. It has been shown that PWV could improve cardiovascular event prediction in models that included standard risk factors. Consequently, it might therefore enable better identification of populations at high-risk of cardiovascular morbidity and mortality. The present review is focused on a survey of different pharmacological therapeutic options for decreasing arterial stiffness. The influence of several groups of drugs is described: antihypertensive drugs (angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, calcium channel blockers, beta-blockers, diuretics, and nitrates), statins, peroral antidiabetics, advanced glycation end-products (AGE) cross-link breakers, anti-inflammatory drugs, endothelin-A receptor antagonists, and vasopeptidase inhibitors. All of these have shown some effect in decreasing arterial stiffness. Nevertheless, further studies are needed which should address the influence of arterial stiffness diminishment on major adverse cardiovascular and cerebrovascular events (MACCE).

The effect of sitagliptin versus glibenclamide on arterial stiffness, blood pressure, lipids, and inflammation in type 2 diabetes mellitus patients

AIM

This study evaluated the effect of sitagliptin versus glibenclamide on arterial stiffness, blood pressure, lipid profile, oxidative stress, and high-sensitivity C-reactive protein (hsCRP) in type 2 diabetes mellitus patients.

SUBJECTS AND METHODS

Forty diabetes patients, inadequately controlled on metformin, were randomly assigned to either sitagliptin (100 mg/day) or glibenclamide (5 mg/day) for 3 months. Following a 1-month washout period, a crossover switch from glibenclamide to sitagliptin and vice versa was performed for an additional 3 months. Arterial stiffness, 24-h ambulatory blood pressure monitoring, lipids, hsCRP, glycated hemoglobin, fasting glucose, STAT-8-isoprostane (a measure of oxidative stress), body mass index (BMI), and waist circumference were measured at baseline and at 3 months with each of the study drugs.

RESULTS

Thirty-four patients completed the study. Glibenclamide had a better glucose-lowering effect than sitagliptin, but this was associated with more hypoglycemic events. BMI increased following glibenclamide treatment, whereas sitagliptin proved weight-neutral. Mean BMI gain was +0.5±1.0 kg/m(2) for glibenclamide versus -0.01±0.9 kg/m(2) for sitagliptin (P<0.001). Triglyceride levels significantly dropped following sitagliptin, although they remained unaltered after glibenclamide treatment. Mean triglyceride decrease was -18.4±45 mg/mL after sitagliptin but -0.2±57 mg/dL following glibenclamide treatment (P=0.018). There was no change in low-density lipoprotein, high-density lipoprotein, arterial stiffness, blood pressure monitoring, hsCRP, or STAT-8-isoprostane with each of the study drugs.

CONCLUSIONS

Sitagliptin, but not glibenclamide, demonstrated a significant beneficial effect on BMI and triglyceride levels. However, arterial stiffness, blood pressure, oxidative stress, and inflammatory status were not significantly affected by adding sitagliptin or glibenclamide to metformin-treated type 2 diabetes patients.

Pharmacological modulation of arterial stiffness

Arterial stiffness has emerged as an important marker of cardiovascular risk in various populations and reflects the cumulative effect of cardiovascular risk factors on large arteries, which in turn is modulated by genetic background. Arterial stiffness is determined by the composition of the arterial wall and the arrangement of these components, and can be studied in humans non-invasively. Age and distending pressure are two major factors influencing large artery stiffness. Change in arterial stiffness with drugs is an important endpoint in clinical trials, although evidence for arterial stiffness as a therapeutic target still needs to be confirmed. Drugs that independently affect arterial stiffness include antihypertensive drugs, mostly blockers of the renin-angiotensin-aldosterone system, hormone replacement therapy and some antidiabetic drugs such as glitazones. While the quest continues for 'de-stiffening drugs', so far only advanced glycation endproduct cross-link breakers have shown promise.

Arterial stiffness: from physiology to clinical implications

Current European guidelines for the management of arterial hypertension introduce the assessment of arterial stiffness by pulse wave velocity (PWV) as an index of hypertension-related cardiovascular target organ damage. An increase in arterial stiffness is related to haemodynamic modifications at the level of the aorta, leading to a rise in cardiac afterload, a reduction in coronary perfusion and an overstretch of the aortic walls. An increasing number of studies have demonstrated the accuracy of PWV as an independent predictor of cardiovascular events and cardiovascular mortality in patients with different co-morbidities and cardiovascular risk. Many strategies have demonstrated their efficacy in preventing arterial stiffening; therapy of arterial hypertension is the mainstay in the management of patients with increased PWV and altered pulse wave reflection. Literature has clearly shown the specific efficacy of drugs interfering with the renin-angiotensin-aldosterone system and calcium-channel blockers in the control of central haemodynamics, particularly when compared with β-blockers (β-adrenoceptor antagonists). The same action has not yet been demonstrated on PWV. Further studies are needed to assess the real relative efficacy of different drug classes on the management of arterial stiffness and the clinical and prognostic relevance of these therapies.

Pioglitazone: beyond glucose control

Pioglitazone is an oral antidiabetic agent that decreases insulin resistance in adipose tissue, liver and muscles. This action is mediated by its link to a nuclear receptor called peroxisome proliferator-activated receptor-gamma. By improving insulin sensitivity, hepatic glucose production decreases and glucose uptake increases in the peripheral tissues. Beyond these effects on glucose metabolism, pioglitazone has positive effects on lipid metabolism, blood pressure, endothelial function, adiponectin and C-reactive protein levels. These make pioglitazone treatment effective beyond glucose control. In this article, current evidence concerning pioglitazone in the treatment of Type 2 diabetes will be reviewed.

Head-to-head comparison of the cardio-ankle vascular index between patients with acute coronary syndrome and stable angina pectoris

We aimed to evaluate whether there was a difference in the arterial stiffness assessed by the cardio-ankle vascular index (CAVI) between patients with acute coronary syndrome (ACS) and those with stable angina pectoris (SAP). A total of 199 consecutive patients, 79 with ACS and 120 with SAP, who underwent emergency or elective coronary revascularization were enrolled. The CAVI was measured within 2 days after the procedures, and was compared between the ACS and SAP patients. As parameters related to arteriosclerosis, carotid intima-media thickness (IMT) and number of stenotic coronary vessels were also evaluated. Although IMT was significantly greater in SAP patients (2.1±1.1 vs. 2.4±0.9; P=0.022), CAVI was significantly higher in ACS patients (10.0±1.7 vs. 9.3±1.3; P=0.0012). After an adjustment for the clinical parameters with a significant difference between the two patient groups, CAVI remained significantly higher in ACS patients than in SAP patients (odds ratio 1.92, 95% confidence interval 1.30-3.02; P=0.0023). A multiple linear regression analysis revealed that age (β=0.44; P<0.0001) and ACS (β=0.3; P<0.0001) were the independent determinants of CAVI. A significant decrease in CAVI was observed at 6 months of follow-up as compared with the acute phase in 18 patients with ACS (10.9±1.6 vs. 10.0±1.5; P=0.019). In conclusion, CAVI was significantly and independently higher in patients with ACS than in those with SAP, which might result from a transient increase in the CAVI caused by acute myocardial ischemia.