Vascular and Endothelial Function in Youth with Type 2 Diabetes Mellitus

Surface markers on microparticles involved in obesity-derived diseases

AIMS

This review aimed to investigate the different types of microparticles playing role in obesity-related diseases. Additionally, the factors participating in changing the microparticles amount in obese people will also be discussed.

MATERIAL & METHODS

The authors collected the relevant articles published until 2023 and these are carefully selected from three scientific databases based on keywords.

KEY FINDINGS

It has been revealed that exercise might change the microparticle content in the body. The other factor which participates in obesity process is the oxidative stress which is increased in microparticles. Moreover, the obesity is implicated in metabolic conditions including diabetes and cardiovascular diseases.

SIGNIFICANCE

More than one-third of people on the planet today are known as overweight individuals. Microparticles (MPs) are small membrane-bound vesicles that are found in healthy people's blood and are elevated in patients with pathological conditions such as obesity. MPs mostly come from platelets, leukocytes, endothelial cells, and vascular smooth muscle cells. Considering the effect of obesity on microparticles, these small membrane-bound vesicles might play a crucial role in preventing or treatment of obesity.

Approach to the Patient: Youth-Onset Type 2 Diabetes

Youth-onset type 2 diabetes is a growing epidemic with a rising incidence worldwide. Although the pathogenesis and diagnosis of youth-onset type 2 diabetes are similar to adult-onset type 2 diabetes, youth-onset type 2 diabetes is unique, with greater insulin resistance, insulin hypersecretion, and faster progression of pancreatic beta cell function decline. Individuals with youth-onset type 2 diabetes also develop complications at higher rates within short periods of time compared to adults with type 2 diabetes or youth with type 1 diabetes. The highest prevalence and incidence of youth-onset type 2 diabetes in the United States is among youth from minoritized racial and ethnic groups. Risk factors include obesity, family history of type 2 diabetes, comorbid conditions and use of medications associated with insulin resistance and rapid weight gain, socioeconomic and environmental stressors, and birth history of small-for-gestational-age or pregnancy associated with gestational or pregestational diabetes. Patients with youth-onset type 2 diabetes should be treated using a multidisciplinary model with frequent clinic visits and emphasis on addressing of social and psychological barriers to care and glycemic control, as well as close monitoring for comorbidities and complications. Intensive health behavior therapy is an important component of treatment, in addition to medical management, both of which should be initiated at the diagnosis of type 2 diabetes. There are limited but growing pharmacologic treatment options, including metformin, insulin, glucagon-like peptide 1 receptor agonists, and sodium-glucose cotransporter 2 inhibitors. Although long-term outcomes are not fully known, metabolic/bariatric surgery in youth with type 2 diabetes has led to improved cardiometabolic outcomes.

Endothelial Dysfunction in Diabetes Mellitus: New Insights

Endothelial dysfunction (ED) is an important marker of future atherosclerosis and cardiovascular disease, especially in people with diabetes. This article summarizes the evidence on endothelial dysfunction in people with diabetes and adds different perspectives that can affect the presence and severity of ED and its consequences. We highlight that data on ED in type 1 diabetes are lacking and discuss the relationship between ED and arterial stiffness. Several interesting studies have been published showing that ED modulates microRNA, microvesicles, lipid levels, and the endoplasmatic reticulum. A better understanding of ED could provide important insights into the microvascular complications of diabetes, their treatment, and even their prevention.

Physiological and pathological characteristics of vascular endothelial injury in diabetes and the regulatory mechanism of autophagy

Vascular endothelial injury in diabetes mellitus (DM) is the major cause of vascular disease, which is closely related to the occurrence and development of a series of vascular complications and has a serious negative impact on a patient's health and quality of life. The primary function of normal vascular endothelium is to function as a barrier function. However, in the presence of DM, glucose and lipid metabolism disorders, insulin resistance, inflammatory reactions, oxidative stress, and other factors cause vascular endothelial injury, leading to vascular endothelial lesions from morphology to function. Recently, numerous studies have found that autophagy plays a vital role in regulating the progression of vascular endothelial injury. Therefore, this article compares the morphology and function of normal and diabetic vascular endothelium and focuses on the current regulatory mechanisms and the important role of autophagy in diabetic vascular endothelial injury caused by different signal pathways. We aim to provide some references for future research on the mechanism of vascular endothelial injury in DM, investigate autophagy's protective or injurious effect, and study potential drugs using autophagy as a target.

Insights into SGLT2 inhibitor treatment of diabetic cardiomyopathy: focus on the mechanisms

Among the complications of diabetes, cardiovascular events and cardiac insufficiency are considered two of the most important causes of death. Experimental and clinical evidence supports the effectiveness of SGLT2i for improving cardiac dysfunction. SGLT2i treatment benefits metabolism, microcirculation, mitochondrial function, fibrosis, oxidative stress, endoplasmic reticulum stress, programmed cell death, autophagy, and the intestinal flora, which are involved in diabetic cardiomyopathy. This review summarizes the current knowledge of the mechanisms of SGLT2i for the treatment of diabetic cardiomyopathy.

N6-methylation of RNA-bound adenosine regulator HNRNPC promotes vascular endothelial dysfunction in type 2 diabetes mellitus by activating the PSEN1-mediated Notch pathway

AIM

The regulatory mechanism of m6A regulators in vascular endothelial function of type 2 diabetes mellitus (T2DM) remains largely unknown. We addressed this issue based on the data retrieved Gene Expression Omnibus (GEO) database and experimental validations.

METHODS

Expression of m6A methylation regulators was evaluated in T2DM samples of GSE76894 dataset and GSE156341 dataset. Further analysis of candidate m6A methylation regulators was conducted in the thoracic aorta of db/db mice and high glucose (HG)-induced human umbilical vein endothelial cells (HUVECs). Ectopic expression and depletion experiments were conducted to detect effects of m6A methylation regulators on vascular endothelial function in T2DM.

RESULTS

It emerged that three m6A methylation regulators (HNRNPC, RBM15B, and ZC3H13) were highly expressed in T2DM, which were related to vascular EC function, showing diagnostic values for T2DM. HNRNPC expression in the thoracic aorta of db/db mice was higher than that in heterozygous db mice, and HNRNPC expression in HG-induced HUVECs was upregulated when compared with normal glucose-exposed HUVECs. Furthermore, HNRNPC activated PSEN1-dependent Notch pathway to induce eNOS inactivation and NO production decrease, thereby causing vascular endothelial dysfunction in T2DM.

CONCLUSIONS

HNRNPC impaired vascular endothelial function to enhance the development of vascular complications in T2DM through PSEN1-mediated Notch signaling pathway.

Correlation analysis of carotid plaque in young patients with newly diagnosed type 2 diabetes and platelet-to-lymphocyte ratio and neutrophil-lymphocyte ratio

OBJECTIVE

Platelet-to-lymphocyte ratio (PLR) and neutrophil-lymphocyte ratio (NLR) have been reported to be related to atherosclerosis. The relationship between PLR, NLR, and carotid atherosclerotic plaque in young patients with newly diagnosed type 2 diabetes has not been clinically reported. This study aimed to analyze the relationship between PLR, NLR, and carotid plaques in young patients with newly diagnosed type 2 diabetes.

METHOD

The total 268 patients were divided into the intima-media-thickening (IMT) group (116 cases) and plaque group (152 cases). The plaque group was divided into grade I (62 cases), grade II (47 cases), and grade III groups (43 cases). The counts of platelets, neutrophils, and lymphocytes were determined.

RESULTS

The diagnostic effect of PLR and NLR was evaluated by the receiver-operating characteristic curve (ROC) and areas under the curve (AUC). The PLR and NLR values in the observation group were higher than those in the control group; these two values in the plaque group were also higher than those in the IMT group. The two values in the grade III plaque group were higher than those in grade II. The values in the grade II plaque group were also higher than those in the grade I plaque group. The ROC of PLR and NLR were 0.722 and 0.653, and the AUC of PLR and NLR were 111.086 and 2.240. PLR yielded a sensitivity of 0.789 and a specificity of 0.612. Neutrophil-lymphocyte ratio yielded a sensitivity of 0.809 and a specificity of 0.511.

CONCLUSION

The PLR and NLR may be related to carotid inflammation in patients and positively correlated with carotid plaque.

Endothelial Peripheral Arterial Tonometry (Endo-PAT 2000) use in paediatric patients: a systematic review

OBJECTIVES

Endo Peripheral Artery Tonometry (EndoPAT-2000) is a non-invasive technology for measuring endothelial dysfunction (ED). The reactive hyperaemia index (RHI) is resulted and is low when ED is present. We aim to synthesise the literature on paediatric ED that used Endo-PAT analysis.

DESIGN

A comprehensive systematic review was conducted from January 2015 to March 2021. The databases included Cochrane, MEDLINE EBSCO, EMBASE (Ovid), PUBMED and CINAHL EBSCO. Exclusion criteria were: (1) If a study used a different device, for example, (2) If the study had no results. Inclusion criteria were: (1) Published in the English, (2) more than 50% of study subjects were in the paediatric age range, (3) data relevant to paediatric age range children could be extrapolated from all data, where not all study subjects were children.

RESULTS

Following the removal of duplicates, 156 articles were initially identified. Following exclusion, 50 articles were included for review. We have subdivided these papers into different systems for ease of reference and have reported our findings in six tables: patients with type 1/2 diabetes, obesity, cardiovascular, respiratory, psychiatric conditions and miscellaneous diseases. For each, the study design, population, control group (if available), RHI results and conclusions were reported.

CONCLUSIONS

A number of papers using Endo-PAT for children with various chronic diseases have evidence of ED. However, in many cases, there has only been a single cohort study using Endo-PAT. Further studies are required to validate these findings and to help characterise the cardiovascular risk profile of children with chronic disease. Further studies are also required that will characterise more completely the cardiovascular risk profile of these children.Consensus on other vascular risk markers that could be included in future studies is ideal and if accomplished, this would facilitate meta-analyses of studies of relatively rare conditions.

Effects of L-Citrulline Supplementation and Aerobic Training on Vascular Function in Individuals with Obesity across the Lifespan

Children with obesity are at higher risk for developing cardiometabolic diseases that once were considered health conditions of adults. Obesity is commonly associated with cardiometabolic risk factors such as dyslipidemia, hyperglycemia, hyperinsulinemia and hypertension that contribute to the development of endothelial dysfunction. Endothelial dysfunction, characterized by reduced nitric oxide (NO) production, precedes vascular abnormalities including atherosclerosis and arterial stiffness. Thus, early detection and treatment of cardiometabolic risk factors are necessary to prevent deleterious vascular consequences of obesity at an early age. Non-pharmacological interventions including L-Citrulline (L-Cit) supplementation and aerobic training stimulate endothelial NO mediated vasodilation, leading to improvements in organ perfusion, blood pressure, arterial stiffness, atherosclerosis and metabolic health (glucose control and lipid profile). Few studies suggest that the combination of L-Cit supplementation and exercise training can be an effective strategy to counteract the adverse effects of obesity on vascular function in older adults. Therefore, this review examined the efficacy of L-Cit supplementation and aerobic training interventions on vascular and metabolic parameters in obese individuals.

Endothelial impairment evaluation by peripheral arterial tonometry in pediatric endocrinopathies: A narrative review

Endothelial dysfunction (ED) is characterized by an imbalance between vasodilator and vasoconstriction agents. Several pathological conditions clinically diagnosed in childhood and adolescence are characterized by ED and increased risk for early development of microangiopathic and macroangiopathic impairment, in particular type 1 diabetes mellitus (T1DM), T2DM, obesity, metabolic syndromeand pituitary dysfunction associated to various endocrinopathies. More recently insulin resistance following chemotherapy or radiotherapy for tumors, bone marrow transplantation for hematological malignancies (i.e., cancer survivors), or immunosuppressive treatment for solid organ transplantation has been observed. Assessment of ED by means of non-invasive techniques is the gold standard for early ED detection before clinical manifestation. It is aimed to recognize patients at risk and to avoid the development and progression of more serious illnesses. Reactive hyperemia-peripheral artery tonometry is a noninvasive technique to assess peripheral endothelial function by measuring modifications in digital pulse volume during reactive hyperemia, and represents a non-invasive, reproducible and operator-independent tool able to detect precocious ED. This narrative review aimed to provide an overview of the most important papers regarding ED detection by EndoPat 2000 in children and adolescents with different endocrine diseases. A comprehensive search of English language articles was performed in the MEDLINE database without using other search filters except the publication interval between 2005 and 2020.

Oral glucose tolerance response curve predicts disposition index but not other cardiometabolic risk factors in healthy adolescents

OBJECTIVES

In obese adults the shape of the glucose response curve during an oral glucose tolerance test (OGTT) predicts future type 2 diabetes. Patients with an incessant increase or monophasic curves have increased risk compared to those with biphasic curves. Since type 2 diabetes is associated with increased cardiometabolic risk, we studied whether differences in OGTT response curve are associated with differences in cardiometabolic risk factors in healthy adolescents across a wide body mass index (BMI) range.

METHODS

Sixty-nine (33F/36M), white adolescents (age: 15.2 ± 1.7 years; BMI: 21.5 ± 4.7 kg/m²; mean ± SD) were studied. Risk factors measured included percent body fat, blood pressure, lipids, augmentation index, reactive hyperemia, endothelin 1, plasminogen activator 1, inflammatory markers (interleukin 6, c-reactive protein), insulin secretion, insulin sensitivity (Matusda index), and disposition index (DI).

RESULTS

Thirty-two subjects had biphasic responses; 35 subjects had monophasic responses and two females had incessant increases. Sex did not affect the frequency of responses. Glucose area under the curve during OGTT was greater in those with a mono vs. biphasic curves (p=0.01). Disposition index was markedly lower in subjects with a monophasic curve than in those with a biphasic curve (3.6 [2.3-5.0] vs. 5.8 [3.8-7.6], median [25th, 75th%] p=0.003). Triglyceride to high-density lipoprotein cholesterol (HDL) ratio was higher in subjects with a monophasic curve (p=0.046).

CONCLUSIONS

The decreased disposition index indicates that in healthy adolescents a monophasic response to OGTT is due to decreased insulin secretion relative to the degree of insulin resistance present. This was not associated with differences in most other cardiometabolic risk markers.

TRIAL REGISTRATION

Clinical Trials.gov, NCT02821104.

Pediatric Type 2 Diabetes: Not a Mini Version of Adult Type 2 Diabetes

Pediatric type 2 diabetes mellitus (T2DM) is increasing in incidence, with risk factors including obesity, puberty, family history of T2DM in a first-degree or second-degree relative, history of small-for-gestational-age at birth, child of a gestational diabetes pregnancy, minority racial group, and lower socioeconomic status. The pathophysiology of T2DM consists of insulin resistance and progression to pancreatic beta-cell failure, which is more rapid in pediatric T2DM compared with adult T2DM. Treatment options are limited. Treatment failure and nonadherence rates are high in pediatric T2DM; therefore, early diagnosis and treatment and new pharmacologic options and/or effective behavioral interventions are needed.

Dyslipidemia in adolescents and young adults with type 1 and type 2 diabetes: a retrospective analysis

Background

Youth onset type 1 diabetes (T1D) and type 2 diabetes (T2D) is increasing and associated with earlier vascular complications and mortality. Dyslipidemia is an important modifiable cardiovascular (CVD) risk factor that is under-recognized and undertreated in youth with T1D and T2D. Given this, we evaluated the prevalence and associations between lipid concentrations and clinical CVD risk factors in youth with T1D compared to T2D at our large ethnically diverse diabetes center.

Methods

A retrospective chart review was performed, evaluating patients with T1D or T2D seen at least once in clinic from 2015 to 2017, age 10–22 years of age, duration of diabetes at least 6 months on the date of most recent LDL-cholesterol (LDL-C) concentration, and not on statin therapy. We performed independent and multivariable linear regressions of LDL-C and HDL-cholesterol (HDL-C) concentrations.

Results

There were 32.7% with T1D (n = 1701) and 47.7% with T2D (n = 298) with LDL-C above recommend goal (> 100 mg/dL/2.6 mmol/L). Furthermore, there were 9% with T1D and 16.4% with T2D with LDL > 130 mg/dL (> 3.4 mmol/L), who likely met criteria for starting statin therapy. Higher LDL-C and/or lower HDL-C were associated with increased age, diabetes duration, higher HbA1C, female sex, Hispanic ethnicity, obesity, and T2D. After adjusting for these risk factors in a multivariable linear regression model, the association of higher LDL-C and lower HDL-C was higher with T2D than T1D.

Conclusions

This highlights the need for more aggressive dyslipidemia screening and treatment in youth with diabetes, especially T2D. At our institution we have created and instituted quality improvement algorithms to try to address this need.

[Vasoprotective Effects of Prolonged Therapy With Perindopril A in Patients with Hypertension Including Concomitant Type 2 Diabetes Mellitus]

Objective Investigate the dynamics of morphological and functional markers of vascular remodeling in patients with arterial hypertension (AH), including those with concomitant type 2 diabetes mellitus (DM2), during 12-month administration of perindopril A.Material and Methods The study included patients with grade I-II AH, with and without DM2 (30 and 32 patients, respectively), who underwent outpatient correction of initially ineffective antihypertensive therapy and administration of perindopril A, 10 mg/day. Morphological and functional parameters of vascular remodeling were evaluated in all patients at baseline and at 12 months using photoplethysmography. Stiffness index (SI) and phase shift (PS) were measured in large vessels. Reflection index (RI) and occlusion index (OI) were measured in microvessels. Computed nailfold videocapillaroscopy was used to determine capillary density (CD) at rest (CDr), CD during venous occlusion test (CDvo), and CD during reactive hyperemia test (CDrh). Data are medians [interquartile range].Results After 12-month administration of perindopril A, the morphological and functional parameters of vascular remodeling in AH patients without DM2 significantly improved at all vascular levels. SI decreased to 9.25 [7.8; 10.93 ] m/s and PS increased to 7.4 [5.6; 9.05] ms. In microvasculature, a statistically significant reduction was observed in RI, 31 [27; 36.5]%, and an increase was observed in OI, which characterizes endothelium function, 1.75 [1.68; 1.9]. Capillary CDr significantly increased to 40.5 [34.93; 46] cap/mm2, as did CDvo and CDrh. At the same time, in the group of patients with AH and DM2, a significant improvement was observed for the large vessels. SI decreased to 9.8 [9.08; 10.58] m/s, and PS increased to 6.95 [5.13; 10.08]. The RI index, reflecting the structural condition of arterioles, significantly decreased to 34 [25.9; 45.53]%, and the OI index, characterizing endothelial function, did not change significantly, 1.4 [1.3; 1.6]. Capillary CDr significantly increased to 31.55 [27.68; 34.7 ] cap/mm2; however, CDvo and CDrh did not change significantly. Renal function improved in both groups.Conclusion Both groups demonstrated improvement of morphological parameters at all levels of the arterial bed. However, patients with AH and concomitant DM2 showed no improvement of the endothelial function of arterioles and capillaries compared to improvement in AH patients without DM2. This reflected the more severe endothelial dysfunction present in AH patients with DM2.

Heart Rate Variability and Cardiac Autonomic Dysfunction: Prevalence, Risk Factors, and Relationship to Arterial Stiffness in the Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) Study

OBJECTIVE

To determine whether prior type 2 diabetes (T2D) treatment or glycemic control over time are independently associated with heart rate variability (HRV) and whether the presence of cardiac autonomic dysfunction is associated with arterial stiffness in young adults with youth-onset T2D enrolled in the Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) study.

RESEARCH DESIGN AND METHODS

Heartbeats over 10 min were measured to derive the normal R-Rs (NN intervals). Outcomes included the standard deviation of the NN intervals (SDNN), the root mean square differences of successive NN intervals (RMSSD), percent of NN beats that differ by more than 50 ms (PNN50), and the low-frequency (LF) power domain, high-frequency (HF) power domain, and their ratio (LF:HF). Autonomic dysfunction was defined as ≥3 of 5 abnormal HRV indices compared with obese controls from a separate study.

RESULTS

A total of 397 TODAY participants were evaluated 7 years after randomization. TODAY participants had reduced HRV (SDNN 58.1 ± 29.6 ms vs. controls 67.1 ± 25.4 ms; P < 0.0001) with parasympathetic loss (RMSSD 53.2 ± 36.7 ms vs. controls 67.9 ± 35.2 ms; P < 0.0001) with sympathetic overdrive (LF:HF ratio 1.4 ± 1.7 vs. controls 1.0 ± 1.1; P < 0.0001). Cardiac autonomic dysfunction was present in 8% of TODAY participants, and these participants had greater pulse wave velocity compared with those without dysfunction (P = 0.0001). HRV did not differ by randomized treatment, but higher hemoglobin A1c (HbA_1c) over time was independently associated with lower SDNN and RMSSD and higher LF:HF ratio after adjustment for age, race-ethnicity, sex, and BMI.

CONCLUSIONS

Young adults with youth-onset T2D show evidence of cardiac autonomic dysfunction with both parasympathetic and sympathetic impairments that are associated with higher HbA_1c.

Vascular Remodeling Markers in Patients with Essential Arterial Hypertension Depending on Presence of Type 2 Diabetes Mellitus

Aim. To study some vascular remodeling markers in hypertensive patients depending on the presence of type 2 diabetes mellitus.Material and methods. The study included patients with essential hypertension 1-2 degrees of increase in blood pressure with/without type 2 diabetes (30 and 32 patients respectively). Using photoplethysmography in combination with reactive hyperemia test structural and functional markers of vascular remodeling were determined: in large vessels – stiffness index and phase shift; in microvessels – reflection index and the occlusion index. Using the computer video capillaroscopy of the nail bed the density of the capillary network at rest, after venous occlusion and after the test with reactive hyperemia was determined. ELISA was used for determining the level of humoral markers of endothelium dysfunction and vascular bed remodeling: metalloproteinase 9, metalloproteinase 9 inhibitor, E-selectin, endothelin, transforming growth factor (TGF-β1), endothelial growthfactor A.Results. In compare with hypertensive patients in hypertensive patients with type 2 diabetes significantly higher stiffness index values (11.15 [10.05; 12.35] vs 10.15 [8.83; 11.83] m/s; p=0.04) were found as well as significantly lower (p=0.00) capillary network density at rest (26.4 [24.2; 27.6] vs 35.1 [33.0; 45.0] cap/mm2; p=0.00) after the tests with reactive hyperemia (29 [24; 33.3] vs 40.0 [35.0;43.3] cap/mm2; p=0.00) and venous occlusion (32.5 [27.8; 34.5] vs 40.0 [33.0; 45.0] cap/mm2). In hypertensive patients with type 2 diabetes significantly higher levels of TFG-β1 (11648 [4117.8; 37933.8] vs 3938.5 [1808.8; 7694] pg/ml; p=0.00) and significantly lower levels of endothelin-1 (0,46 [0,29;1,3] vs 1.73 [0.63; 2.30] ng/ml; p=0.01) was detected in compare with hypertensive patients without type 2 diabetes.Conclusion. In both groups some signs of vascular remodeling were found at the level of both large arteries and microvessels (arterioles and capillaries). However, the group of hypertension + type 2 diabetes mellitus had statistically significantly more pronounced changes in arterial stiffness, capillary network density, as well as humoral markers levels of fibrosis and endothelial dysfunction. 

Association between Irisin, hs-CRP, and Metabolic Status in Children and Adolescents with Type 2 Diabetes Mellitus

Proinflammatory cytokines and the novel myokine irisin, a cleavage product of FNDC5, have been found to play a role in obesity and type 2 diabetes mellitus (T2DM). Irisin has been shown to increase browning of adipose tissue, thermogenesis, energy expenditure, and insulin sensitivity, yet its association with inflammatory markers is still limited. Circulating irisin has been found to be increased in obesity, while in adult subjects with T2DM decreased levels have been found. However, data establishing the association of circulating irisin in children and adolescents with T2DM has not been described in the literature. The objective of this study was to determine irisin plasma concentration and its association with metabolic and adiposity markers and with hs-CRP, a surrogate marker of inflammation used in clinical practice, in a pediatric population with T2DM. A cross-sample of 40 Mexican children and adolescents aged 7-17 were recruited, 20 diagnosed with T2DM and 20 healthy controls. Plasma irisin levels were found to be lower in the T2DM group compared with controls, which could be attributed to a reduced PGC-1α activity in muscle tissue with a consequent decrease in FNDC5 and irisin expression. Irisin concentration was found to be positively correlated with HDL-c, LDL-c, and total cholesterol, while negatively correlated with BMI, waist circumference, and triglycerides. However, after multiple regression analysis, only HDL-c correlation remained significant. hs-CRP was higher in the T2DM group and positively associated with adiposity markers, unfavorable lipid profile, insulin levels, and HOMA-IR, but no association with irisin was found. Given the favorable metabolic effects attributed to irisin, the low plasma levels found in children and adolescents with T2DM could exacerbate the inflammatory and metabolic imbalances and the intrinsic cardiovascular risk of this disease. We propose an "irisin-proinflammatory/anti-inflammatory axis" to explain the role of irisin as a metabolic regulator in obesity and T2DM.

Relationship between Systemic Vascular Characteristics and Retinal Nerve Fiber Layer Loss in Patients with Type 2 Diabetes

Retinal nerve fiber layer (RNFL) loss in diabetic patients is especially common regardless of diabetic retinopathy (DR). The correlations between nonglaucomatous RNFL loss and systemic characteristics in diabetic patients have aroused interests in many aspects. 167 subjects with type 2 diabetes who underwent evaluation for arterial stiffness and cardiovascular autonomic function using heart rate variability (HRV) were included in this study. Arterial stiffness was measured using cardio-ankle vascular index (CAVI) and ankle-brachial index (ABI). Multivariate regression analysis was performed to determine factors influencing the presence of RNFL loss according to age. Factors determining the superior location of diabetic RNFL loss were also investigated. CAVI were worse in patients with RNFL loss, especially in those with old age (≥50 yrs) (p = 0.037). Influential factor of RNFL defect in old group was ABI (p = 0.007). However, in young group (<50 yrs), HRV parameter (low-frequency/high-frequency ratio) determined the presence of RNFL loss (p = 0.040). Significant determinants of superior RNFL defect in old subjects were CAVI and ABI (p = 0.032 and p = 0.024). For young diabetic patients, autonomic dysfunction may have relationship with RNFL loss, but as patients get older, arterial stiffness could aggravate vascular autoregulation and diabetic RNFL loss. RNFL loss in diabetes may be correlated with systemic vascular conditions.

Alteration of Vascular Responsiveness to Uridine Adenosine Tetraphosphate in Aortas Isolated from Male Diabetic Otsuka Long-Evans Tokushima Fatty Rats: The Involvement of Prostanoids

We investigated whether responsiveness to dinucleotide uridine adenosine tetraphosphate (Up₄A) was altered in aortas from type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats compared with those from age-matched control Long-Evans Tokushima Otsuka (LETO) rats at the chronic stage of disease. In OLETF aortas, we observed the following: (1) Up₄A-induced contractions were lower than those in the LETO aortas under basal conditions, (2) slight relaxation occurred due to Up₄A, but this was not observed in phenylephrine-precontracted LETO aortas, (3) acetylcholine-induced relaxation was reduced (vs. LETO), and (4) prostanoid release (prostaglandin (PG)F_2α, thromboxane (Tx)A₂ metabolite, and PGE₂) due to Up₄A was decreased (vs. LETO). Endothelial denudation suppressed Up₄A-induced contractions in the LETO group, but increased the contractions in the OLETF group. Under nitric oxide synthase (NOS) inhibition, Up₄A induced contractions in phenylephrine-precontracted aortas; this effect was greater in the LETO group (vs. the OLETF group). The relaxation response induced by Up₄A was unmasked by cyclooxygenase inhibitors, especially in the LETO group, but this effect was abolished by NOS inhibition. These results suggest that the relaxant component of the Up₄A-mediated response was masked by prostanoids in the LETO aortas and that the LETO and OLETF rats presented different contributions of the endothelium to the response.