Simultaneous control of hyperglycemia and oxidative stress normalizes endothelial function in type 1 diabetes

Impact of Physical Exercise on Platelets: Focus on Its Effects in Metabolic Chronic Diseases

Chronic disorders are strongly linked to cardiovascular (CV) diseases, and it is unanimously accepted that regular exercise training is a key tool to improving CV risk factors, including diabetes, dyslipidemia, and obesity. Increased oxidative stress due to an imbalance between reactive oxygen species production and their scavenging by endogenous antioxidant capacity is the common ground among these metabolic disorders, and each of them affects platelet function. However, the correction of hyperglycemia in diabetes and lipid profile in dyslipidemia as well as the lowering of body weight in obesity all correlate with amelioration of platelet function. Habitual physical exercise triggers important mechanisms related to the exercise benefits for health improvement and protects against CV events. Platelets play an important role in many physiological and pathophysiological processes, including the development of arterial thrombosis, and physical (in)activity has been shown to interfere with platelet function. Although data reported by studies carried out on this topic show discrepancies, the current knowledge on platelet function affected by exercise mainly depends on the type of applied exercise intensity and whether acute or habitual, strenuous or moderate, thus suggesting that physical activity and exercise intensity may interfere with platelet function differently. Thus, this review is designed to cover the aspects of the relationship between physical exercise and vascular benefits, with an emphasis on the modulation of platelet function, especially in some metabolic diseases.

Altered sperm fate in the reproductive tract milieu due to oxidative stress leads to sub-fertility in type 1 diabetes females: A Drosophila-based study

AIMS

Female sub-fertility, a prominent complication due to Type 1 diabetes (T1D), is generally attributed to disturbances in menstrual cycles and/or ovarian defects/disorders. T1D women, however, are high in oxidative stress, although the impact of the same on their reproduction and associated events remains unknown. Therefore, we assessed the repercussions of elevated oxidative stress on the sperm fate (storage/utilization) in the reproductive tract milieu of T1D females and their fertility using the Drosophila T1D model (Df[dilp1-5]), which lacks insulin-like peptides and displays reduced female fertility.

MAIN METHODS

We mated Df[dilp1-5] females to normal males and thereafter examined sperm storage and/or utilization in conjunction with oxidative stress parameters in mated Df[dilp1-5] females at different time points. Also, the impact of antioxidant (Amla or Vitamin C) supplementation on the above oxidative stress parameters in Df[dilp1-5] females and the consequences on their sperm and fertility levels were examined.

KEY FINDINGS

Df[dilp1-5] females showed elevated oxidative stress parameters and a few of their reproductive tract proteins are oxidatively modified. Also, these females stored significantly fewer sperm and also did not utilize sperm as efficiently as their controls. Surprisingly, amelioration of the oxidative stress in Df[dilp1-5] females' milieu through antioxidant (Amla or vitamin C) supplementation enhanced sperm storage and improved fertility.

SIGNIFICANCE

Hyperglycemia coupled with elevated oxidative stress within the female reproductive tract environment affects the sperm fate, thereby reducing female fertility in T1D. In addition, these findings suggest that antioxidant supplementation may substantially aid in the mitigation of sub-fertility in T1D females.

Glycaemic management in diabetes: old and new approaches

HbA_1c is the most used parameter to assess glycaemic control. However, evidence suggests that the concept of hyperglycaemia has profoundly changed and that different facets of hyperglycaemia must be considered. A modern approach to glycaemic control should focus not only on reaching and maintaining optimal HbA_1c concentrations as early as possible, but to also do so by reducing postprandial hyperglycaemia, glycaemic variability, and to extend as much as possible the time in range in near-normoglycaemia. These goals should be achieved while avoiding hypoglycaemia, which, should it occur, should be reverted to normoglycaemia. Modern technology, such as intermittently scanned glucose monitoring and continuous glucose monitoring, together with new drug therapies (eg, ultra-fast insulins, SGLT2 inhibitors, and GLP-1 receptor agonists), could help to change the landscape of glycaemia management based on HbA_1c in favour of a more holistic approach that considers all the different aspects of this commonly oversimplified pathophysiological feature of diabetes.

Integrated pancreatic microcirculatory profiles of streptozotocin-induced and insulin-administrated type 1 diabetes mellitus

OBJECTIVE

As an integrated system, pancreatic microcirculatory disturbance plays a vital role in the pathogenesis of type 1 diabetes mellitus (T1DM), which involves changes in microcirculatory oxygen and microhemodynamics. Therefore, we aimed to release type 1 diabetic and insulin-administrated microcirculatory profiles of the pancreas.

METHODS

BALB/c mice were assigned to control, T1DM, and insulin-administrated groups randomly. T1DM was induced by intraperitoneal injection of streptozotocin (STZ). 1.5 IU insulin was administrated subcutaneously to keep the blood glucose within the normal range. After anesthetizing by isoflurane, the raw data set of pancreatic microcirculation was collected by the multimodal device- and computer algorithm-based microcirculatory evaluating system. After adjusting outliers and normalization, pancreatic microcirculatory oxygen and microhemodynamic data sets were imported into the three-dimensional module and compared.

RESULTS

Microcirculatory profiles of the pancreas in T1DM exhibited a loss of microhemodynamic coherence (significantly decreased microvascular blood perfusion) accompanied by an impaired oxygen balance (significantly decreased PO₂ , SO₂ , and rHb). More importantly, with insulin administration, the pathological microcirculatory profiles were partially restored. Meanwhile, there were correlations between pancreatic microcirculatory blood perfusion and PO₂ levels.

CONCLUSIONS

Our findings establish the first integrated three-dimensional pancreatic microcirculatory profiles of STZ-induced and insulin-administrated T1DM.

The Role of Oxidative Stress and Antioxidants in Diabetic Wound Healing

Foot ulcers are one of the most common and severe complication of diabetes mellitus with significant resultant morbidity and mortality. Multiple factors impair wound healing include skin injury, diabetic neuropathy, ischemia, infection, inadequate glycemic control, poor nutritional status, and severe morbidity. It is currently believed that oxidative stress plays a vital role in diabetic wound healing. An imbalance of free radicals and antioxidants in the body results in overproduction of reactive oxygen species which lead to cell, tissue damage, and delayed wound healing. Therefore, decreasing ROS levels through antioxidative systems may reduce oxidative stress-induced damage to improve healing. In this context, we provide an update on the role of oxidative stress and antioxidants in diabetic wound healing through following four perspectives. We then discuss several therapeutic strategies especially dietary bioactive compounds by targeting oxidative stress to improve wounds healing.

Muscle Oxygen Supply and Use in Type 1 Diabetes, From Ambient Air to the Mitochondrial Respiratory Chain: Is There a Limiting Step?

OBJECTIVE

Long before clinical complications of type 1 diabetes (T1D) develop, oxygen supply and use can be altered during activities of daily life. We examined in patients with uncomplicated T1D all steps of the oxygen pathway, from the lungs to the mitochondria, using an integrative ex vivo (muscle biopsies) and in vivo (during exercise) approach.

RESEARCH DESIGN AND METHODS

We compared 16 adults with T1D with 16 strictly matched healthy control subjects. We assessed lung diffusion capacity for carbon monoxide and nitric oxide, exercise-induced changes in arterial O₂ content (SaO₂, PaO₂, hemoglobin), muscle blood volume, and O₂ extraction (via near-infrared spectroscopy). We analyzed blood samples for metabolic and hormonal vasoactive moieties and factors that are able to shift the O₂-hemoglobin dissociation curve. Mitochondrial oxidative capacities were assessed in permeabilized vastus lateralis muscle fibers.

RESULTS

Lung diffusion capacity and arterial O₂ transport were normal in patients with T1D. However, those patients displayed blunted exercise-induced increases in muscle blood volume, despite higher serum insulin, and in O₂ extraction, despite higher erythrocyte 2,3-diphosphoglycerate. Although complex I- and complex II-supported mitochondrial respirations were unaltered, complex IV capacity (relative to complex I capacity) was impaired in patients with T1D, and this was even more apparent in those with long-standing diabetes and high HbA_1c. [Formula: see text]O_2max was lower in patients with T1D than in the control subjects.

CONCLUSIONS

Early defects in microvascular delivery of blood to skeletal muscle and in complex IV capacity in the mitochondrial respiratory chain may negatively impact aerobic fitness. These findings are clinically relevant considering the main role of skeletal muscle oxidation in whole-body glucose disposal.

The Comprehensive Glucose Pentagon: A Glucose-Centric Composite Metric for Assessing Glycemic Control in Persons With Diabetes

BACKGROUND

Composite metrics have the potential to provide more complete and clinically useful information about glycemic control than traditional individual metrics such as hemoglobin A1C, %/time/area under curve of hypoglycemia and hyperglycemia.

METHODS

Using five key metrics that are derived from continuous glucose monitoring, we developed a new, multicomponent composite metric, the Comprehensive Glucose Pentagon (CGP) that demonstrates glycemic control both numerically and visually. Two of its axes are composite metrics-the intensity of hypoglycemia and intensity of hyperglycemia. This approach eliminates the use of the surrogate marker, hemoglobin A1C (A1C), and replaces it with glucose-centric metrics.

RESULTS

We reanalyzed the data from two randomized control trials, the STAR 3 and ASPIRE In-Home studies using the CGP. It provided new insights into the effect of sensor-augmented pumping (SAP) in the STAR 3 trial and sensor-integrated pumping with low-glucose threshold suspend (SIP+TS) in the ASPIRE In-Home trial.

CONCLUSIONS

The CGP has the potential to enable health care providers, investigators and patients to better understand the components of glycemic control and the effect of various interventions on the individual elements of that control. This can be done on a daily, weekly, or monthly basis. It also allows direct comparison of the effects on different interventions among clinical trials which is not possible using A1C alone. This new composite metric approach requires validation to determine if it provides a better predictor of long-term outcomes than A1C and/or better predictor of severe hypoglycemia than the low blood glucose index (LBGI).

Carbohydrate restriction with postmeal walking effectively mitigates postprandial hyperglycemia and improves endothelial function in type 2 diabetes

Postprandial hyperglycemia has deleterious effects on endothelial function. Restricting carbohydrate intake and postmeal walking have each been shown to reduce postprandial hyperglycemia, but their combination and subsequent effects on endothelial function have not been investigated. Here, we sought to examine the effect of blunting postprandial hyperglycemia by following a low-carbohydrate diet, with or without postmeal walking exercise, on markers of vascular health in type 2 diabetes (T2D). In a randomized crossover design, individuals with T2D ( n = 11) completed three 4-day controlled diet interventions consisting of 1) low-carbohydrate diet alone (LC), 2) low-carbohydrate diet with 15-min postmeal walks (LC + Ex), and 3) low-fat control diet (CON). Fasting blood samples and brachial artery flow-mediated dilation (%FMD) were measured before and after each intervention. Total circulating microparticles (MPs), endothelial MPs, platelet MPs, monocyte-platelet aggregates, and adhesion molecules were assessed as biomarkers of vascular health. There was a significant condition × time interaction for %FMD ( P = 0.01), with post hoc tests revealing improved %FMD after LC + Ex (+0.8 ± 1.0%, P = 0.02), with no change after LC or CON. Endothelial MPs were significantly reduced with the LC diet by ~45% (from 99 ± 60 to 44 ± 31 MPs/μl, P = 0.02), with no change after LC + Ex or CON (interaction: P = 0.04). Total MPs were lower (main effect time: P = 0.02), whereas monocyte-platelet aggregates were higher (main effect time: P < 0.01) after all interventions. Plasma adhesion molecules and C-reactive protein were unaltered. Attenuating postprandial hyperglycemic excursions using a low-carbohydrate diet combined with postmeal walking appears to be an effective strategy to improve endothelial function in individuals with T2D. NEW & NOTEWORTHY Carbohydrate restriction and postmeal walking lower postprandial hyperglycemia in individuals with type 2 diabetes. Here, we show that the combination significantly improved endothelial function and that carbohydrate restriction alone reduced circulating endothelial microparticles in individuals with type 2 diabetes. Listen to this article's corresponding podcast at http://ajpheart.podbean.com/e/low-carb-diet-and-exercise-improve-endothelial-health/ .

Premeal insulin decreases arterial stiffness in children with type 1 diabetes

OBJECTIVE

To determine the effects of omitting meal time insulin on arterial stiffness in children with type 1 diabetes.

RESEARCH DESIGN AND METHODS

In this prospective, randomized, crossover study, radial artery tonometry and augmentation index adjusted to heart rate 75 (AI₇₅ ) were used to measure arterial stiffness. Children were randomized to receive or omit premeal insulin and completed the crossover portion of the study on a subsequent day. AI₇₅ was determined when fasting, 1, and 2 h postmeal.

RESULTS

When comparing change in AI₇₅ from baseline to 1 h and baseline to 2 h, when subjects received premeal insulin vs. no insulin, AI₇₅ was 4.5 units lower at 1 h (p = 0.011, 95% CI:1.1 lower to 8 lower) and 4.3 units lower at 2 h (p = 0.062, 95% CI: 0.2 higher to 8.9 lower) (n = 40).

CONCLUSIONS

Arterial stiffness is decreased by premeal insulin in children with type 1 diabetes.

Mechanism of Generation of Oxidative Stress and Pathophysiology of Type 2 Diabetes Mellitus: How Are They Interlinked?

Oxidative stress has been considered as a major hallmark for the pathogenesis and development of type 2 diabetes mellitus (T2DM), but still it is debatable whether it is a mere aggregation of inflammatory-induced responses or clinical entity that underlies with various pathophysiological factors. In this regard, the latest studies have shown the increasing trends for the involvement of reactive oxygen species (ROS) and oxidative stress in the pathogenesis and development of T2DM. ROS are highly reactive species and almost all cellular components are chemically changed due to the influence of ROS that ultimately results in the production of lipid peroxidation. Lipid peroxidation is a major causative factor for the development of oxidative stress that leads to overt T2DM and its associated micro- and macro-vascular complications. In this article, we have briefly described the role of various causative factors, transcriptional and metabolic pathways which are responsible to increase the production of oxidative stress, a most pivotal factor for the pathogenesis and development of T2DM. Therefore, we conclude that measurement of oxidative stress biomarkers may be one of the optional tool for the diagnosis and prediction of T2DM. Moreover, the key findings described in this article also provides a new conceptual framework for forthcoming investigations on the role of oxidative stress in pathogenesis of T2DM and drug discovery. J. Cell. Biochem. 118: 3577-3585, 2017. © 2017 Wiley Periodicals, Inc.

Anti-nociceptive and anti-inflammatory potentials of Vernoniaamygdalina leaf extract via reductions of leucocyte migration and lipid peroxidation

Background:

Vernonia amygdalina is well known as a medicinal plant in folk medicine as antidiabetic, anthelmintic, antimalarial, laxative/purgative, and expectorant among others.

Aim:

This study was conducted to investigate the antinociceptive and anti-inflammatory effects of V. amygdalina.

Materials and Methods:

Methanol extract of V. amygdalina leaf (MEVA) was evaluated for antinociceptive effect and possible mechanisms of action in the presence of naloxone (1 mg/kg), atropine (2 mg/kg), and prazosin (1 mg/kg) using acetic acid writhing test in mice. The anti-inflammatory effect was evaluated in carrageenan hind paw edema and carrageenan air pouch models. Protein concentration, malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) assays were carried out for its antioxidative activities in inflammation. Hematoxylin and eosin staining was used to assess the level of inflammation.

Results:

From the acetic acid writhing test results, MEVA (50,100 mg/kg) showed significant antinociceptive effect. Naloxone, atropine and prazosin did not significantly reverse the antinociceptive effect of MEVA (50 mg/kg). MEVA (50, 100, and 200 mg/kg) showed dose-dependent inhibition of edema (41.4, 63.0, and 68.6%) at 4 h post-carrageenan injection. In the carrageenan air pouch model, MEVA (200 mg/kg) significantly (P < 0.05) reduced infiltrating leukocytes, protein concentration and MDA levels, while GSH and SOD were unaffected. The histological study showed a reduction in the infiltration of inflammatory cells in MEVA-treated groups.

Conclusion:

V. amygdalina showed antinociceptive activity and anti-inflammatory effect via reductions of leukocyte migration and lipid peroxidation.

Targeting endothelial metaflammation to counteract diabesity cardiovascular risk: Current and perspective therapeutic options

The association of obesity and diabetes, termed "diabesity", defines a combination of primarily metabolic disorders with insulin resistance as the underlying common pathophysiology. Cardiovascular disorders associated with diabesity represent the leading cause of morbidity and mortality in the Western world. This makes diabesity, with its rising impacts on both health and economics, one of the most challenging biomedical and social threats of present century. The emerging comprehension of the genes whose alteration confers inter-individual differences on risk factors for diabetes or obesity, together with the potential role of genetically determined variants on mechanisms controlling responsiveness, effectiveness and safety of anti-diabetic therapy underlines the need of additional knowledge on molecular mechanisms involved in the pathophysiology of diabesity. Endothelial cell dysfunction, resulting from the unbalanced production of endothelial-derived vascular mediators, is known to be present at the earliest stages of insulin resistance and obesity, and may precede the clinical diagnosis of diabetes by several years. Once considered as a mere consequence of metabolic abnormalities, it is now clear that endothelial dysfunctional activity may play a pivotal role in the progression of diabesity. In the vicious circle where vascular defects and metabolic disturbances worsen and reinforce each other, a low-grade, chronic, and 'cold' inflammation (metaflammation) has been suggested to serve as the pathophysiological link that binds endothelial and metabolic dysfunctions. In this paradigm, it is important to consider how traditional antidiabetic treatments (specifically addressing metabolic dysregulation) may directly impact on inflammatory processes or cardiovascular function. Indeed, not all drugs currently available to treat diabetes possess the same anti-inflammatory potential, or target endothelial cell function equally. Perspective strategies pointing at reducing metaflammation or directly addressing endothelial dysfunction may disclose beneficial consequences on metabolic regulation. This review focuses on existing and potential new approaches ameliorating endothelial dysfunction and vascular inflammation in the context of diabesity.

Proanthocyanidins from Vitis vinifera inhibit oxidative stress-induced vascular impairment in pulmonary arteries from diabetic rats

BACKGROUND

Vitis vinifera L. (grape seed extract) is a natural source of proanthocyanidins with antioxidant and free radical-scavenging activities.

HYPOTHESIS

Grape seed extract supplementation may prevent vascular endothelium impairment associated with diabetes mellitus in rat pulmonary artery.

STUDY DESIGN

We evaluated endothelial function of rat pulmonary artery ex-vivo at the intermediate stage (4 weeks) of streptozotocin (STZ)-induced diabetes mellitus. We also evaluated the protective effect of grape seed extract administered daily, beginning the day after diabetes induction, or 15 days after diabetes induction, until the day of sacrifice. In addition, we compared the effect of grape seed extract supplementation with that of vitamin C.

METHODS

Rats were made diabetic with streptozotocin (STZ, 65mg/kg i.v.). Thirty days later rats were sacrificed and pulmonary vessels reactivity and endothelial function compared to that of age-matched healthy animals.

RESULTS

Concentration-response curves to ACh, NE, sodium nitroprusside (NO donor), but not to histamine and iloprost (prostacyclin analog), were significantly altered 4 weeks after STZ-injection. Antioxidant supplementation (3mg/kg/day) with either vitamin C or grape seed extract, starting the day after diabetes induction, significantly improved vasodilation to ACh and SNP. Norepinephrine-induced contractions were preserved by grape seed extract, but not vitamin C supplementation. Conversely, vitamin C but not grape seed extract showed beneficial effects contrasting the loss of body weight in diabetic animals. Abnormal vascular function was not reversed when antioxidant supplementations were postponed 15 days after the induction of diabetes.

CONCLUSIONS

This study provides scientific support for the therapeutic potential of an antioxidant therapy in endothelial impairment associated with diabetes. A daily supplementation of grape seed proanthocyanidins and/or vitamin C given at the earlier stage of disease may have a complementary role in the pharmacological therapy of diabetes and pulmonary vascular dysfunction.

Sirtuin1-regulated lysine acetylation of p66Shc governs diabetes-induced vascular oxidative stress and endothelial dysfunction

The 66-kDa Src homology 2 domain-containing protein (p66Shc) is a master regulator of reactive oxygen species (ROS). It is expressed in many tissues where it contributes to organ dysfunction by promoting oxidative stress. In the vasculature, p66Shc-induced ROS engenders endothelial dysfunction. Here we show that p66Shc is a direct target of the Sirtuin1 lysine deacetylase (Sirt1), and Sirt1-regulated acetylation of p66Shc governs its capacity to induce ROS. Using diabetes as an oxidative stimulus, we demonstrate that p66Shc is acetylated under high glucose conditions and is deacetylated by Sirt1 on lysine 81. High glucose-stimulated lysine acetylation of p66Shc facilitates its phosphorylation on serine 36 and translocation to the mitochondria, where it promotes hydrogen peroxide production. Endothelium-specific transgenic and global knockin mice expressing p66Shc that is not acetylatable on lysine 81 are protected from diabetic oxidative stress and vascular endothelial dysfunction. These findings show that p66Shc is a target of Sirt1, uncover a unique Sirt1-regulated lysine acetylation-dependent mechanism that governs the oxidative function of p66Shc, and demonstrate the importance of p66Shc lysine acetylation in vascular oxidative stress and diabetic vascular pathophysiology.

The use of probiotic L. fermentum ME-3 containing Reg'Activ Cholesterol supplement for 4 weeks has a positive influence on blood lipoprotein profiles and inflammatory cytokines: an open-label preliminary study

BACKGROUND

Cardiovascular diseases continue to be a challenge and burden to heath. The incidence of type 2 diabetes is increasing. Modifying the (common) risk factors of them is the key of longterm success. The aim of the study was to establish if the special composition of innovative food supplement Reg'Activ Cholesterol (RAC) has a positive influence to the human body cardiovascular-inflammatory and diabetic parameters.

METHODS

Forty-five clinically asymptomatic participants consumed an RAC containing an antioxidative and antiatherogenic probiotic Lactobacillus fermentum ME-3 (LFME-3) for 4 weeks. The parameters measured were total cholesterol, HDL cholesterol, LDL cholesterol, triglyceride, oxLDL, hsCRP, IL-6 and glycosylated haemoglobin (HbA1c%).

RESULTS

The cardiovascular and diabetes risk profile of the participants improved significantly after 4 weeks of the intervention. The reduction of total cholesterol (from 6.5 ± 1.0 to 5.7 ± 0.9 mmol/l, p = 9.90806E-11) was on the account of LDL cholesterol as the HDL cholesterol level rose from 1.60 ± 0.31to 1.67 ± 0.34mml/l, p = 0.01. HbA1c% was reduced from 5.85 ± 0.28 to 5.66 ± 0.25 p = 4.64E-05 and oxLDL decreased from 84 ± 20 to 71 ± 15 U/l, p = 4.66292E-08.

CONCLUSIONS

The consumption of RAC in clinically asymptomatic volunteers with borderline-high values of risk factors for cardiovascular disease (BMI, HbA1c%, LDL cholesterol) for 4 weeks had a positive effect on blood lipoprotein, oxidative stress and inflammatory profile. There are no human trials published before with RAC.

TRIAL REGISTRATION

The trial described here isa n open label pilot study within the framework of a larger special clinical trial ( ISRCTN55339917 ) [Accessed 20 Feb 2016].

Clinical implications of oxidative stress and potential role of natural antioxidants in diabetic vascular complications

AIMS

The possible link between hyperglycaemia-induced oxidative stress (OxS) and diabetic complications is suggested by many in vitro studies. However, not much attention has been paid to the clinical evidence supporting this hypothesis, as well as to their possible therapeutic implications.

DATA SYNTHESIS

Some prospective studies show a direct correlation between an increase in OxS biomarkers and the appearance of diabetes complications. This is consistent with the evidence that any acute increase of glycaemia, particularly post-prandial, and hypoglycaemia causes endothelial dysfunction and inflammation, through the generation of an OxS. However, the detection of free radicals is difficult as they are highly reactive molecules with a short half-life. Instead, the metabolites of OxS are measured. Interventional trials with supplemented antioxidants have failed to show any beneficial effects. Conversely, natural foods show very promising results.

CONCLUSIONS

The "new antioxidant" approach includes the possibility of controlling free radical production and increasing intracellular antioxidant defence, a concept different from the old one, when antioxidant activities implied scavenging the free radicals already produced. A synergistic action in this respect could convincingly be obtained with a balanced 'Mediterranean Diet' (MedD) type. Early intensive glucose control is still the best strategy to avoid OxS and its associated diabetes complications.

The simultaneous control of hyperglycemia and GLP-1 infusion normalize endothelial function in type 1 diabetes

BACKGROUND

To test the effect of normoglycemia and glucagon-like peptide-1 (GLP-1), alone or in combination, on the possible normalization of endothelial function in type 1 diabetes.

METHODS

Fifteen people with type 1 diabetes participated in three experiments: reaching and maintaining normoglycemia for 4h; reaching and maintaining hyperglycemia plus GLP-1 infusion for 4h; and reaching and maintaining normoglycemia for 4h with simultaneous infusion of GLP-1.

RESULTS

Both normoglycemia and GLP-1 infusion restored endothelial function and decreased and plasma 8-iso prostaglandin F2α levels. However, only the combination of normoglycemia and GLP-1 was able to normalize endothelial function.

CONCLUSIONS

This study confirms that long-lasting hyperglycemia in type 1 diabetes induces a permanent alteration which contributes to maintaining endothelial dysfunction even when glycemia is normalized, and that in the presence of normoglycemia, GLP-1 can contribute to normalizing endothelial function.

Evaluation of biochemical and clinical markers of endothelial dysfunction and their correlation with urinary albumin excretion in patients with type 1 diabetes mellitus

Objective Endothelial dysfunction (ED) plays an important role in the pathogenesis of diabetic nephropathy. The purpose of the study was to determine flow mediated endothelial dependent vasodilatation (FMD) measurements and serum soluble (s) endothelin-1 (ET-1), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM-1) levels in patients with type 1 diabetes mellitus (T1DM) with or without increased urinary albumin excretion (UAE) and compare them with the healthy controls. Subjects and methods Seventy three patients with T1DM were enrolled. Patients were divided into two subgroups according to microalbumin measurements in 24-hr urine collections. The diabetic patients without microalbuminuria (41 patients) were defined as Group I and those with microalbuminuria (32 patients) were defined as group II. A hundred age and sex matched healthy subjects participated as the control group (Group III). Serum sET-1, sICAM-1, sVCAM-1 levels and FMD measurements were determined in all participants. Results Median FMD measurement was significantly lower in the diabetic groups compared with the control group (6.6, 6.4 and 7.8% in Group I, II and III, respectively) (p < 0.05). FMD was negatively correlated with age (p = 0.042). Median serum sICAM-1 level was higher in the patient groups compared to the control group (p < 0.05). Median serum sVCAM-1 level was higher in the group of patients with increased albuminuria compared to the normoalbuinuric and the control group (p < 0.05). Serum sVCAM-1 level was found to be positively correlated with degree of urinary albumin excretion (p < 0.001). Conclusion We assume that sVCAM-1 may be used as a predictive marker for risk stratification for nephropathy development and progression.

Clinical Relevance of Biomarkers of Oxidative Stress

SIGNIFICANCE

Oxidative stress is considered to be an important component of various diseases. A vast number of methods have been developed and used in virtually all diseases to measure the extent and nature of oxidative stress, ranging from oxidation of DNA to proteins, lipids, and free amino acids.

RECENT ADVANCES

An increased understanding of the biology behind diseases and redox biology has led to more specific and sensitive tools to measure oxidative stress markers, which are very diverse and sometimes very low in abundance.

CRITICAL ISSUES

The literature is very heterogeneous. It is often difficult to draw general conclusions on the significance of oxidative stress biomarkers, as only in a limited proportion of diseases have a range of different biomarkers been used, and different biomarkers have been used to study different diseases. In addition, biomarkers are often measured using nonspecific methods, while specific methodologies are often too sophisticated or laborious for routine clinical use.

FUTURE DIRECTIONS

Several markers of oxidative stress still represent a viable biomarker opportunity for clinical use. However, positive findings with currently used biomarkers still need to be validated in larger sample sizes and compared with current clinical standards to establish them as clinical diagnostics. It is important to realize that oxidative stress is a nuanced phenomenon that is difficult to characterize, and one biomarker is not necessarily better than others. The vast diversity in oxidative stress between diseases and conditions has to be taken into account when selecting the most appropriate biomarker.

Alpha-lipoic acid as a pleiotropic compound with potential therapeutic use in diabetes and other chronic diseases

Alpha-lipoic acid is a naturally occurring substance, essential for the function of different enzymes that take part in mitochondria's oxidative metabolism. It is believed that alpha-lipoic acid or its reduced form, dihydrolipoic acid have many biochemical functions acting as biological antioxidants, as metal chelators, reducers of the oxidized forms of other antioxidant agents such as vitamin C and E, and modulator of the signaling transduction of several pathways. These above-mentioned actions have been shown in experimental studies emphasizing the use of alpha-lipoic acid as a potential therapeutic agent for many chronic diseases with great epidemiological as well economic and social impact such as brain diseases and cognitive dysfunctions like Alzheimer disease, obesity, nonalcoholic fatty liver disease, burning mouth syndrome, cardiovascular disease, hypertension, some types of cancer, glaucoma and osteoporosis. Many conflicting data have been found concerning the clinical use of alpha-lipoic acid in the treatment of diabetes and of diabetes-related chronic complications such as retinopathy, nephropathy, neuropathy, wound healing and diabetic cardiovascular autonomic neuropathy. The most frequent clinical condition in which alpha-lipoic acid has been studied was in the management of diabetic peripheral neuropathy in patients with type 1 as well type 2 diabetes. Considering that oxidative stress, a imbalance between pro and antioxidants with excessive production of reactive oxygen species, is a factor in the development of many diseases and that alpha-lipoic acid, a natural thiol antioxidant, has been shown to have beneficial effects on oxidative stress parameters in various tissues we wrote this article in order to make an up-to-date review of current thinking regarding alpha-lipoic acid and its use as an antioxidant drug therapy for a myriad of diseases that could have potential benefits from its use.

Correlation of Plasma Lipid Profile with Salivary Oxidative Stress Markers in Type II Diabetes Mellitus Patients

INTRODUCTION

Diabetes is known to be associated with greater production of reactive oxygen species (ROS) like malondialdehyde (MDA) and decreased antioxidants like total thiols and its estimation in plasma is used in monitoring the redox status. The aim of this study was to analyse the association between plasma lipid profile parameters like HDL and LDL with salivary MDA and thiols in diabetic patients.

MATERIALS AND METHODS

Sixty subjects between the age group 35- 70 years who were diagnosed with type II diabetes mellitus based on fasting blood glucose and glycated haemoglobin levels who attended the dental OPD at Kasturba Medical College and Hospital, Manipal consented to participate in this study. Plasma glucose, HDL and LDL were estimated in Cobas autoanalyser by hexokinase method, homogenous enzymatic colorimetric assay and Friedwald's formula respectively. Assessment of glycated hemoglobin was by ion exchange chromatography, MDA by thiobarbituric acid as a substrate and thiols by Ellmann's manual method in plasma and saliva.

RESULTS

The association of plasma LDL with salivary MDA was found to be positive and significant and that with salivary thiols was negative and significant. Also, the association of plasma HDL with salivary MDA was found to be negative and significant and that with salivary thiols was positive and significant.

CONCLUSION

RESULTS indicate the potential of saliva as a tool to monitor prognosis of diabetes.

Determinants of intensive insulin therapeutic regimens in patients with type 1 diabetes: data from a nationwide multicenter survey in Brazil

BACKGROUND

To evaluate the determinants of intensive insulin regimens (ITs) in patients with type 1 diabetes (T1D).

METHODS

This multicenter study was conducted between December 2008 and December 2010 in 28 public clinics in 20 Brazilian cities. Data were obtained from 3,591 patients (56.0% female, 57.1% Caucasian). Insulin regimens were classified as follows: group 1, conventional therapy (CT) (intermediate human insulin, one to two injections daily); group 2 (three or more insulin injections of intermediate plus regular human insulin); group 3 (three or more insulin injections of intermediate human insulin plus short-acting insulin analogues); group 4, basal-bolus (one or two insulin injections of long-acting plus short-acting insulin analogues or regular insulin); and group 5, basal-bolus with continuous subcutaneous insulin infusion (CSII). Groups 2 to 5 were considered IT groups.

RESULTS

We obtained complete data from 2,961 patients. Combined intermediate plus regular human insulin was the most used therapeutic regimen. CSII was used by 37 (1.2%) patients and IT by 2,669 (90.2%) patients. More patients on IT performed self-monitoring of blood glucose and were treated at the tertiary care level compared to CT patients (p < 0.001). The majority of patients from all groups had HbA1c levels above the target. Overweight or obesity was not associated with insulin regimen. Logistic regression analysis showed that economic status, age, ethnicity, and level of care were associated with IT (p < 0.001).

CONCLUSIONS

Given the prevalence of intensive treatment for T1D in Brazil, more effective therapeutic strategies are needed for long term-health benefits.

Influence of a family history of type 2 diabetes, demographic and clinical data on carotid intima-media thickness in patients with type 1 diabetes: a cross-sectional study

Background

Intima-media thickness (IMT) of the common carotid artery is a surrogate end point of cardiovascular disease (CVD). Identifying the factors associated with a higher IMT may contribute to the identification of subjects with higher CVD risk. Our objective was to compare the common carotid IMT of type 1 diabetes patients to healthy control subjects. The secondary objective was to determine factors associated with a higher carotid IMT.

Methods

We conducted a cross-sectional study between March 2009 and October 2013, comprising 127 type 1 diabetes patients and 125 control subjects matched by age, gender and body mass index (BMI). Carotid IMT was measured using semi-automated edge detection software.

Results

Type 1 diabetes patients had a higher median IMT compared with control subjects (0.538; IQR: 0.500-0.607 vs 0.513 mm; IQR: 0.481-0.557, respectively p = 0.001). Women with type 1 diabetes had a higher median IMT difference compared to the control group (0.537; IQR: 0.495-0.596 vs 0.502 mm; IQR: 0.472-0.543, respectively p = 0.003) than did men with type 1 diabetes (0.547; IQR: 0.504-0.613 vs 0.528 mm; IQR: 0.492-0.575, respectively p = 0.2). Age and diabetes duration had an additive effect on the IMT of type 1 diabetes patients. Multivariate gamma regression model analysis showed that in type 1 diabetes patients, the IMT was associated with age (Exp (β) = 1.006, p < 0.001), duration of diabetes (Exp (β) = 1.004, p = 0.001), BMI (Exp (β) = 1.005, p = 0.021), family history of type 2 diabetes (Exp (β) = 1.044, p = 0.033), total cholesterol (Exp (β) = 0.999, p = 0.001) and creatinine clearance (Exp (β) = 1.000, p = 0.043).

Conclusions

Patients with type 1 diabetes have increased IMT, a marker of subclinical atherosclerosis. The CVD risk may be similar between men and women with type 1 diabetes, suggesting a loss of gender protection. Also, CVD risk may be higher in those with a family history of type 2 diabetes. Prospective studies are needed to confirm the predictive value of these findings and the causal effect between IMT and CVD in patients with type 1 diabetes.

Low-molecular-weight fucoidan protects endothelial function and ameliorates basal hypertension in diabetic Goto-Kakizaki rats

Endothelial dysfunction, characterized by impairment of endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) bioavailability, has been implicated in diabetic cardiovascular pathogenesis. In this study, low-molecular-weight fucoidan (LMWF), which has multiple biological activities including anti-inflammatory and anti-oxidative properties, was investigated for its protective effect against endothelial dysfunction in Goto-Kakizaki type 2 diabetic rats. LMWF (50, 100, or 200 mg/kg/day) or probucol (100 mg/kg/day) were given to diabetic rats for 12 weeks. Basal blood pressure, acetylcholine- or flow-mediated relaxation of mesenteric and paw arteries, endothelium-dependent dilation of aorta, eNOS phosphorylation, and NO production were measured using laser Doppler flowmetry, force myograph, hematoxylin and eosin staining, western blot analysis, and an NO assay. We found that LMWF robustly ameliorated the basal hypertension and impairment of endothelium-dependent relaxation in the aorta, as well as mesenteric and paw arteries in diabetic rats. In addition, the reduction in eNOS phosphorylation at Ser1177, eNOS expression, and NO production because of diabetes were partially reversed by LMWF treatment. However, probucol, a lipid-modifying drug with antioxidant properties, displayed only mild effects. Moreover, LMWF induced, in a dose-dependent manner, endothelium-dependent vasodilation and eNOS phosphorylation at Ser1177 in normal aorta, and also promoted Ser1177 phosphorylation and NO synthesis in primary cultured vasoendothelial cells. Thus, these data demonstrate for the first time that fucoidan protects vasoendothelial function and reduces basal blood pressure in type 2 diabetes rats via, at least in part, preservation of eNOS function. Fucoidan is therefore a potential candidate drug for protection of endothelium in diabetic cardiovascular complications.

Vascular function and glucose variability improve transiently following initiation of continuous subcutaneous insulin infusion in children with type 1 diabetes

OBJECTIVE

The effect of continuous subcutaneous insulin infusion (CSII) and glucose variability on vascular health in type 1 diabetes (T1D) is not known. We aimed to determine whether initiation of CSII improves vascular function and reduces glucose variability, independent of changes in HbA1c.

METHODS

Twenty-two children with T1D (12.5 ± 2.9 yr) were reviewed immediately prior, 3 wk, and 12 months after initiation of CSII. Vascular function [flow-mediated dilatation (FMD), glyceryl trinitrate-mediated dilatation (GTN)], glucose variability [mean of daily differences (MODD), mean amplitude of glycaemic excursions (MAGE) and continuous overlapping net glycaemic action (CONGA)], and clinical and biochemical data were measured at each visit. Results for the first two visits were compared to a previously studied cohort of 31 children with T1D who remained on multiple daily injections (MDI).

RESULTS

FMD, GTN, blood pressure, HbA1c, fructosamine, and glucose variability significantly improved 3 wk after CSII commencement (all p < 0.05), but there was no change in the MDI control group. At 3 wk, vascular function related to glucose variability [(FMD: MODD, r = -0.62, p = 0.002) and (GTN: MAGE, r = -0.59, p = 0.004; CONGA-4, r = -0.51, p = 0.01; MODD, r = -0.62, p = 0.002)] but not to blood pressure, HbA1c, or fructosamine. At 12 months, FMD, GTN, blood pressure, and glucose variability returned to baseline levels, while HbA1c deteriorated. Carotid intima media thickness was unchanged over 12 months.

CONCLUSIONS

Initiation of CSII rapidly improves vascular function in association with decreased glucose variability; however, the effects are not sustained with deterioration of metabolic control and glucose variability.

Economic status and clinical care in young type 1 diabetes patients: a nationwide multicenter study in Brazil

The aim of this study is to evaluate the influence of economic status on clinical care provided to Brazilian youths with type 1 diabetes in daily practice, according to the American Diabetes Association's guidelines. This was a cross-sectional, multicenter study conducted between 2008 and 2010 in 28 public clinics in Brazil. Data were obtained from 1,692 patients (55.3 % female, 56.4 % Caucasian), with a mean age of 13 years (range, 1-18), a mean age at diagnosis of 7.1 ± 4 years and diabetes duration of 5 ± 3.7 years. Overall, 75 % of the patients were of a low or very low economic status. HbA1c goals were reached by 23.2 %, LDL cholesterol by 57.9 %, systolic blood pressure by 83.9 % and diastolic blood pressure by 73.9 % of the patients. In total, 20.2 % of the patients were overweight and 9.2 % were obese. Patients from very low economic status were less likely to attend tertiary care level when compared with those from low, medium and high economic status, 64.2 % versus 75.5 % versus 78.3 % and 74.0 %; p < 0.001, respectively. The rate of annual screening for retinopathy, nephropathy and for foot alterations was 66.2, 69.7 and 62.7 %, respectively. Insulin dose, age, very low economic status, daily frequency of self-blood glucose monitoring and female gender were independently associated with poor glycemic control. Screening for diabetic complications and attaining glucose, lipid and blood pressure goals present a challenge for young Brazilian type 1 diabetes patients. The low economic status of the majority of our patients may represent a barrier to reaching these goals.

Aortic distensibility in type 1 diabetes

OBJECTIVE

To evaluate the relationship between long-term glycemia, traditional cardiovascular disease (CVD) risk factors, and ascending aortic stiffness in type 1 diabetes.

RESEARCH DESIGN AND METHODS

Eight hundred seventy-nine subjects in the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) study were evaluated. The stiffness/distensibility of the ascending thoracic aorta (AA) was measured with magnetic resonance imaging. Associations of AA distensibility and CVD risk factors, mean HbA1c, and cardiovascular complications including macroalbuminuria were assessed using multivariate linear regression models.

RESULTS

The mean age of the subjects was 50 ± 7 years (47% women, mean diabetes duration of 28 years). Over 22 years of follow-up, 27% of participants had cardiovascular complications. After adjusting for gender and cohort, AA distensibility was lower with increasing age, mean systolic blood pressure, LDL, and HbA1c measured over an average of 22 years (-26.3% per 10 years, -11.0% per 10 mmHg SBP, -1.8% per 10 mg/dL of LDL, and -9.3% per unit mean HbA1c [%], respectively). Patients with macroalbuminuria had 25% lower AA distensibility compared with those without (P < 0.0001). Lower AA distensibility also was associated with greater ratio of left ventricular mass to volume (-3.4% per 0.1 g/mL; P < 0.0001).

CONCLUSIONS

Our findings indicate strong adverse effects of hypertension, chronic hyperglycemia and macroalbuminuria on AA stiffness in type 1 diabetes in the DCCT/EDIC cohort.

A prescribed Chinese herbal medicine improves glucose profile and ameliorates oxidative stress in Goto-Kakisaki rats fed with high fat diet

Oxidative stress (OS) plays a role in hyperglycemia induced islet β cell dysfunction, however, studies on classic anti-oxidants didn’t show positive results in treating diabetes. We previously demonstrated that the prescribed Chinese herbal medicine preparation “Qing Huo Yi Hao” (QHYH) improved endothelial function in type 2 diabetic patients. QHYH protected endothelial cells from high glucose-induced damages by scavenging superoxide anion and reducing production of reactive oxygen species. Its active component protected C2C12 myotubes against palmitate-induced oxidative damage and mitochondrial dysfunction. In the present study, we investigated whether QHYH protected islet β cell function exacerbated by high fat diet (HFD) in hyperglycemic GK rats. 4-week-old male rats were randomly divided into high HFD feeding group (n = 20) and chow diet feeding group (n = 10). Each gram of HFD contained 4.8 kcal of energy, 52% of which from fat. Rats on HFD were further divided into 2 groups given either QHYH (3 ml/Kg/d) or saline through gastric tube. After intervention, serum glucose concentrations were monitored; IPGTTs were performed without anesthesia on 5 fasting rats randomly chosen from each group on week 4 and 16. Serum malondialdehyde (MDA) concentrations and activities of serum antioxidant enzymes were measured on week 4 and 16. Islet β cell mass and OS marker staining was done by immunohistochemistry on week 16. QHYH prevented the exacerbation of hyperglycemia in HFD feeding GK rats for 12 weeks. On week 16, it improved the exacerbated glucose tolerance and prevented the further loss of islet β cell mass induced by HFD. QHYH markedly decreased serum MDA concentration, increased serum catalase (CAT) and SOD activities on week 4. However, no differences of serum glucose concentration or OS were observed on week 16. We concluded that QHYH decreased hyperglycemia exacerbated by HFD in GK rats by improving β cell function partly via its antioxidant effect.

Ascorbic acid blocks hyperglycemic impairment of endothelial function in adolescents with type 1 diabetes

OBJECTIVE

To determine whether acute ascorbic acid infusions alter the effect of hyperglycemia on endothelial function in adolescents with type 1 diabetes.

RESEARCH DESIGN AND METHODS

The forearm blood flow (FBF) reactive hyperemic response to 5 min of upper arm occlusion was studied in eight adolescents with type 1 diabetes during euglycemic and hyperglycemic insulin clamp (40 mU/m2/min) with and without ascorbic acid infusion (3 mg/min).

RESULTS

The ratio of post- to preocclusion FBF decreased during hyperglycemia without ascorbic acid (p = 0.013), but did not change during hyperglycemia with ascorbic acid. The changes during hyperglycemia were different between the two studies (p = 0.038). Similar results were found when the percent change in forearm vascular resistance following occlusion was assessed.

CONCLUSIONS

These results indicate that antioxidant treatment with ascorbic acid blocks acute hyperglycemic impairment of endothelial function in adolescents with type 1 diabetes.

Dyslipidemia associated with poor glycemic control in type 2 diabetes mellitus and the protective effect of metformin supplementation

The nature of the dyslipidemia associated with diabetes mellitus is complex and is the major risk factor for atherosclerosis and coronary artery disease. Aim of this study was to assess the effect of glycemic control, achieved by metformin, glibenclamide and insulin, on lipid profile in type 2 diabetic patients. One hundred and sixty-five type 2 diabetes mellitus patients were classified into good glycemic control (Group I) and poor glycemic control (Group II) on the basis of their blood HbA1c values. The Group II was characterized with high serum triglyceride (190.46 ± 15.20 mg/dl), total cholesterol (175.3 ± 6.31 mg/dl) as well as high LDL-cholesterol (109.0 ± 5.88 mg/dl). Significant correlations were evident between HbA1c and dyslipidemia, particularly serum TG (r = 0.28, P < 0.05), and between HbA1c and total cholesterol (r = 0.310, P < 0.05). Better glycemic control and improved dyslipidemia were observed in patients on combination therapy of metformin plus glibenclamide.

Mesenteric endothelial dysfunction in a cardiopulmonary bypass rat model: the effect of diabetes

BACKGROUND

Diabetes is a risk factor for perioperative complications after cardiac surgery. We studied its effects on mesenteric endothelial function in a cardiopulmonary bypass (CPB) model.

METHODS

Forty Wistar rats were divided into four groups: sham (D-CPB-), cardiopulmonary bypass (D-CPB+), diabetic (D+CPB-) and diabetic that have undergone CPB (D+CPB+). Two samples of mesenteric artery were used for nitric oxide synthase (NOS) Western blot analysis, and two others for assessing contractile response and endothelium relaxations. Nitrite products and tumour necrosis factor-alpha (TNF-α) were assessed as markers of inflammatory response.

RESULTS

We observed an enhanced contractile response to the α-adrenergic agonist associated with impairment of mesenteric vasorelaxation in D+CPB+ rats. Western immunoblot analysis of D+CPB+ highlighted an additive effect of hyper-expression of inducible NOS. A significantly increased inflammatory response was observed after CPB in diabetic animals.

CONCLUSIONS

This work confirms the potential deleterious impact of diabetes on the mesenteric endothelium during CPB in cardiac surgery.

Gene silencing of the mitochondrial adaptor p66(Shc) suppresses vascular hyperglycemic memory in diabetes

RATIONALE

Hyperglycemic memory may explain why intensive glucose control has failed to improve cardiovascular outcomes in patients with diabetes. Indeed, hyperglycemia promotes vascular dysfunction even after glucose normalization. However, the molecular mechanisms of this phenomenon remain to be elucidated.

OBJECTIVE

The present study investigated the role of mitochondrial adaptor p66(Shc) in this setting.

METHODS AND RESULTS

In human aortic endothelial cells (HAECs) exposed to high glucose and aortas of diabetic mice, activation of p66(Shc) by protein kinase C βII (PKCβII) persisted after returning to normoglycemia. Persistent p66(Shc) upregulation and mitochondrial translocation were associated with continued reactive oxygen species (ROS) production, reduced nitric oxide bioavailability, and apoptosis. We show that p66(Shc) gene overexpression was epigenetically regulated by promoter CpG hypomethylation and general control nonderepressible 5-induced histone 3 acetylation. Furthermore, p66(Shc)-derived ROS production maintained PKCβII upregulation and PKCβII-dependent inhibitory phosphorylation of endothelial nitric oxide synthase at Thr-495, leading to a detrimental vicious cycle despite restoration of normoglycemia. Moreover, p66(Shc) activation accounted for the persistent elevation of the advanced glycated end product precursor methylglyoxal. In vitro and in vivo gene silencing of p66(Shc), performed at the time of glucose normalization, blunted ROS production, restored endothelium-dependent vasorelaxation, and attenuated apoptosis by limiting cytochrome c release, caspase 3 activity, and cleavage of poly (ADP-ribose) polymerase.

CONCLUSIONS

p66(Shc) is the key effector driving vascular hyperglycemic memory in diabetes. Our study provides molecular insights for the progression of diabetic vascular complications despite glycemic control and may help to define novel therapeutic targets.

Metabolic memory for vascular disease in diabetes

Although the terms "metabolic memory" and "legacy effect" have been used to describe the prolonged benefits of good blood glucose control, the former is now recognized as a phenomenon related to the prolonged harm produced mainly by hyperglycemia. At least three randomized clinical trials (Diabetes Control and Complications Trial in type 1 diabetes, United Kingdom Prospective Diabetes Study and Steno-2 in type 2 diabetes) have demonstrated that patients treated intensively for a period of time have a lower risk of micro- and macrovascular complications that persists during subsequent follow-up, even after their tight control has relented and the levels of glycated hemoglobin in the conventionally treated group improve. The mechanisms are not fully understood but most probably relate to the physiopathology of vascular complications of diabetes, and in recent years a unifying theory has been emerging to understand them. The excess superoxide anion produced by the mitochondria in response to hyperglycemia leads through disturbances at the nuclear level to the accumulation of potentially harmful substances such as advanced glycated end-products, protein kinase C, and nuclear factor κB, which are directly implicated in the development of vascular complications in diabetes. These adverse effects are not reversed when the high blood glucose is corrected, and some may be permanent because of epigenetic changes. Some antidiabetes drugs and antioxidant substances have produced partial reversibility of the mechanisms involved in the metabolic memory at the experimental level, but probably the best strategy is to optimize the metabolic control as early as possible, even before diabetes is diagnosed.

The emerging challenge in diabetes: the "metabolic memory"

Large randomized studies have established that early intensive glycemic control reduces the risk of diabetic complications, both micro and macrovascular. However, epidemiological and prospective data support a long-term influence of early metabolic control on clinical outcomes. This phenomenon has recently been defined as "metabolic memory." Potential mechanisms for propagating this "memory" may be the production of reactive species unrelated to the presence of hyperglycemia, depending on the previous production of AGEs which can maintain RAGE over-expression, on the level of glycation of mitochondrial proteins and on the amount of mtDNA produced, all conditions able to induce an altered gene expression which may be persistent even when glycemia is normalized. Clinically, the emergence of this "metabolic memory" suggests the need for a very early aggressive treatment aiming to "normalize" the metabolic control and the addition of agents which reduce cellular reactive species and glycation in addition to normalizing glucose levels in diabetic patients in order to minimize long-term diabetic complications.

Management of diabetes mellitus: could simultaneous targeting of hyperglycemia and oxidative stress be a better panacea?

The primary aim of the current management of diabetes mellitus is to achieve and/or maintain a glycated hemoglobin level of ≤6.5%. However, recent evidence indicates that intensive treatment of hyperglycemia is characterized by increased weight gain, severe hypoglycemia and higher mortality. Besides, evidence suggests that it is difficult to achieve and/or maintain optimal glycemic control in many diabetic patients; and that the benefits of intensively-treated hyperglycemia are restricted to microvascular complications only. In view of these adverse effects and limitations of intensive treatment of hyperglycemia in preventing diabetic complications, which is linked to oxidative stress, this commentary proposes a hypothesis that “simultaneous targeting of hyperglycemia and oxidative stress” could be more effective than “intensive treatment of hyperglycemia” in the management of diabetes mellitus.

Mitochondrial redox studies of oxidative stress in kidneys from diabetic mice

Chronic hyperglycemia during diabetes leads to increased production of reactive oxygen species (ROS) and increased oxidative stress (OS). Here we investigated whether changes in the metabolic state can be used as a marker of OS progression in kidneys. We examined redox states of kidneys from diabetic mice, Akita(/+) and Akita(/+);TSP1(-/-) mice (Akita mice lacking thrombospondin-1, TSP1) with increasing duration of diabetes. OS as measured by mitochondrial redox ratio (NADH/FAD) was detectable shortly after the onset of diabetes and further increased with the duration of diabetes. Thus, cryo fluorescence redox imaging was used as a quantitative marker of OS progression in kidneys from diabetic mice and demonstrated that alterations in the oxidative state of kidneys occur during the early stages of diabetes.

Leukocyte telomere length is associated with complications of type 2 diabetes mellitus

OBJECTIVE

The key goal of diabetes management is to prevent complications. While the patho-physiological mechanisms responsible for diabetes complications have been extensively studied, at present it is impossible to predict which patient with diabetes could develop complications. In recent years, the role of leukocyte telomere length in the pathogenesis of cardiovascular disease and Type 2 diabetes has been investigated. However, studies aiming to investigate the role of telomeres in the development and progression of Type 2 diabetes, as well as diabetic complications, are still lacking. As a consequence, this study aimed to verify whether leukocyte telomere length is associated with the presence and the number of diabetic complications in a sample of patients with Type 2 diabetes.

METHODS

This is a cross-sectional study. Nine hundred and one subjects were enrolled, including 501 patients with Type 2 diabetes, of whom 284 had at least one complication and 217 were without complications, and 400 control subjects. Leukocyte telomere length was measured by quantitative real-time PCR.

RESULTS

Patients with diabetes complications had significantly shorter leukocyte telomere length than both patients without diabetes complications and healthy control subjects. Moreover, among patients with diabetes complications, leukocyte telomere length became significantly and gradually shorter with the increasing number of diabetes complications. The magnitude of the effect of the decrease of the abundance of telomeric template vs. a single-copy gene length (T/S ratio) on complications is described by the estimated odds ratio OR=5.44 (95%CI 3.52-8.42).

CONCLUSIONS

The results of the study support the hypothesis that telomere attrition may be a marker associated with the presence and the number of diabetic complications.

Uric acid levels are associated with microvascular endothelial dysfunction in patients with Type 1 diabetes

AIMS

Recent data identified uric acid as an independent risk factor for cardiovascular disease. The aim of the present study was to assess the association between uric acid and endothelial dysfunction in 57 patients with Type 1 diabetes and 53 healthy control subjects.

METHODS

Microvascular endothelial function was evaluated using laser Doppler perfusion monitoring coupled with pharmacological (iontophoretic administration of acetylcholine and sodium nitroprusside) and physiological (post-occlusive reactive hyperaemia and thermal hyperaemia) stimuli.

RESULTS

Uric acid was higher in subjects without diabetes than in those with diabetes (P = 0.03). Microvascular vasodilator response to acetylcholine was significantly reduced in Type 1 diabetes (P = 0.002) and was correlated to disease duration (r = -0.3, P = 0.01), triglyceride (r = -0.37, P = 0.005), insulin dose (r = -0.28, P = 0.03), fasting plasma glucose levels (r = -0.3, P = 0.02), HbA(1c) (r = -0.34, P = 0.001) and uric acid (r = -0.3, P = 0.005). On stepwise multivariate analysis, age, HbA(1c) and uric acid were the most important independent variables that were associated with the endothelium-dependent response in Type 1 diabetes (P = 0.02).

CONCLUSIONS

Glycaemic control and uric acid in the normal range were the most important contributing factors to the decreasing endothelium-dependent responses associated with Type 1 diabetes. Consequently, uric acid could be a new potential marker of microvascular endothelial dysfunction in these patients. Further studies are required to explore the clinical relevance of the relationship between uric acid levels, oxidative stress and endothelial dysfunction in patients with Type 1 diabetes, as well as whether treatment with uric acid-lowering drugs for slight elevations in uric acid would benefit these patients.

Interrelationship between myocardial perfusion imaging, coronary calcium score, and endothelial function in asymptomatic diabetics and controls

BACKGROUND

Coronary artery disease is a leading cause of death among diabetics, and silent ischemia is a major concern in patients with diabetes mellitus (DM).

METHODS

To detect the prevalence of ischemia in diabetics by myocardial perfusion imaging (MPI), and compare it to a control group without DM but with coronary risk factors, as well as to explore the relationship between silent ischemia, endothelial dysfunction, and coronary calcium, 59 patients (Group I) and 42 controls (Group II) were included. All underwent clinical and laboratory evaluations, gated MPI, brachial artery vasodilation measured by ultrasonography, and coronary calcium score (CCS).

RESULTS

Twenty diabetics showed perfusion defects, vs seven controls (P = .04). There was no significant difference between both groups regarding the brachial artery vasodilator responsiveness: 4.49% ± 4.26% (diabetics) vs 4.70% ± 4.98% (controls). Mean CCS was 74 in diabetics vs five in controls (P = .01). The only risk factor significantly associated with an abnormal MPI was the presence of diabetes (P = .03). In the whole population of patients and in diabetics, the abnormal endothelium-dependent vasodilation, the CCS >100, and the cholesterol/HDL ratio >4, showed an OR >1. CCS exhibited the higher OR among the whole population: OR 2.15 [95% CI 0.42-10.99]; while for diabetics it was the cholesterol/HDL ratio: OR 3.95 [95% CI 0.71-21.84].

CONCLUSIONS

Reversible perfusion defects and coronary calcium are more frequent in diabetics. CCS, abnormal endothelium-dependent vasodilation, and cholesterol/HDL ratio higher than 4, showed an association with perfusion abnormalities in asymptomatic diabetics.

The possible protective role of glucagon-like peptide 1 on endothelium during the meal and evidence for an "endothelial resistance" to glucagon-like peptide 1 in diabetes

OBJECTIVE

Glucagon-like peptide 1 (GLP-1) stimulates insulin secretion. However, GLP-1 also improves endothelial function in diabetes.

RESEARCH DESIGN AND METHODS

Sixteen type 2 diabetic patients and 12 control subjects received a meal, an oral glucose tolerance test (OGTT), and two hyperglycemic clamps, with or without GLP-1. The clamps were repeated in diabetic patients after 2 months of strict glycemic control.

RESULTS

During the meal, glycemia, nitrotyrosine, and plasma 8-iso prostaglandin F2α (8-iso-PGF2a) remained unchanged in the control subjects, whereas they increased in diabetic patients. Flow-mediated vasodilation (FMD) decreased in diabetes, whereas GLP-1 increased in both groups. During the OGTT, an increase in glycemia, nitrotyrosine, and 8-iso-PGF2a and a decrease in FMD were observed at 1 h in the control subjects and at 1 and 2 h in the diabetic patients. In the same way, GLP-1 increased in both groups at the same levels of the meal. During the clamps, in both the control subjects and the diabetic patients, a significant increase in nitrotyrosine and 8-iso-PGF2a and a decrease in FMD were observed, effects that were significantly reduced by GLP-1. After improved glycemic control, hyperglycemia during the clamps was less effective in producing oxidative stress and endothelial dysfunction and the GLP-1 administration was most effective in reducing these effects.

CONCLUSIONS

Our data suggest that during the meal GLP-1 can simultaneously exert an incretin effect on insulin secretion and a protective effect on endothelial function, reasonably controlling oxidative stress generation. The ability of GLP-1 in protecting endothelial function seems to depend on the level of glycemia, a phenomenon already described for insulin secretion.

Evaluation of antioxidative and anti-inflammatory potential of hesperidin and naringin on the rat air pouch model of inflammation

BACKGROUND

Anti-inflammatory and antioxidative potential of hesperidin and naringin was carried out considering the rat air pouch model of inflammation.

METHODS

Reference dose of hesperidin (H) or naringin (N) or indomethacin (I) was administered to the rat air pouches. The pouches were induced by injecting sterile air into the intra-scapular region of the rats followed by carrageenan (AP + C) administration. Rats injected only with air (AP) served as controls.

RESULTS

The AP + C group, showed an increase in the exudate lipid peroxidation (LPO), reduced glutathione (GSH), TNF-α, activity of catalase (CAT), total leukocytes and neutrophils along with tissue edema and infiltration of inflammatory cells. Increases in tissue nitrite, LPO, GSH, SOD (superoxide dismutase) and CAT were recorded. Increased CAT and SGPT with concomitant decrease in ALP were observed in serum. When treated with indomethacin (AP + C + I), all the alterations in the exudate, tissue and serum shifted towards normalcy, except LPO in exudate and nitrite in tissue, while, hesperidin (AP + C + H) or naringin (AP + C + N) treatment normalized all the alterations.

CONCLUSION

It seems that both naringin and hesperidin are anti-inflammatory and antioxidative in nature, but hesperidin proved to be better than indomethacin and naringin because of more pronounced pharmacological actions without tissue toxicity.

Hyperglycaemia and the vessel wall: the pathophysiological aspects on the atherosclerotic burden in patients with diabetes

Large randomised studies have established that early intensive glycaemic control reduces the risk of diabetic complications, both microvascular and macrovascular. However, epidemiological and prospective data support a long-term influence of early metabolic control on clinical outcomes. This phenomenon has recently been defined as 'metabolic memory'. Furthermore, evidence suggests that 'glucose variability' may also be an independent risk factor for cardiovascular complications in diabetes. Studies suggest that all these different situations of hyperglycaemia share a common pathogenetic mechanism, increased oxidative stress, producing an endothelial dysfunction. The therapeutic challenge derived from these evidences is a need not only for an early tight glycaemic control, but also for maintaining glycaemia within a strict normal narrow range.

Effect of acute hyperglycaemia, long-term glycaemic control and insulin on endothelial dysfunction and inflammation in Type 1 diabetic patients with different characteristics

OBJECTIVE

To investigate the possibility of reversing endothelial dysfunction and inflammation by glucose normalization, antioxidants and insulin per se, in different subgroups of Type 1 diabetic patients.

METHODS

Three subgroups of Type 1 diabetic patients were studied: patients within 1 month of diagnosis (subgroup 1); patients with approximately 5 years' disease duration and with glycated haemoglobin (HbA(1c)) <or= 7.0% (subgroup 2) or > 7.0% since diagnosis (subgroup 3). Participants underwent four procedures: 2-h hyperglycaemic clamp followed by: (A) 12 h near-normalization of blood glucose, with the addition of vitamin C during the last 6 h; (B) 12-h vitamin C and near-normalization of blood glucose for the last 6 h; (C) both vitamin C and near-normalization of blood glucose for 12 h; (D) hyperglycaemic-hyperinsulinaemic clamp for 12 h, with the addition of vitamin C during the last 6 h.

RESULTS

After 2 h of hyperglycaemia, markers of endothelial dysfunction, nitrotyrosine, 8-iso prostaglandin F2alpha, soluble intercellular adhesion molecule-1, soluble vascular adhesion molecule-1, interleukin (IL)-6 and IL-18 were increased in all the subgroups. Levels were normalized, at all time points, by treatments A, B and C in the subgroups 1 and 2. In the third subgroup, levels were normalized only by the simultaneous normalization of blood glucose and vitamin C treatment. During treatment D, the levels were improved at 6 h in all the subgroups, but normalized at 12 h only after vitamin C in subgroups 1 and 2, but not in subgroup 3.

CONCLUSIONS

This study suggests that different subgroups of Type 1 diabetic patients react identically to acute hyperglycaemia and insulin, but differently to glucose normalization.