Martin Prázný

Comparison of laser-Doppler flowmetry with biochemical indicators of endothelial dysfunction related to early microangiopathy in Type 1 diabetic patients

The aim of this study was to compare biochemical markers of endothelial activation with microcirculation measured by laser-Doppler flowmetry in Type 1 diabetic patients with or without microangiopathy. A total of 44 Type 1 diabetic patients were subdivided into those with (n=24) and without (n=20) microangiopathy according to ophthalmological findings and the presence or absence of microalbuminuria. The control group consisted of 25 healthy people of comparable age, sex, and body mass index. Postocclusive reactive hyperemia (PORH) and thermal hyperemia (TH, at 44 degrees C) were measured at the forearm. Serum N-acetyl-beta-glucosaminidase (NAG) activity, serum E-selectin, and ICAM-1 concentrations were used as biochemical markers of endothelial dysfunction. A significantly lower velocity of perfusion increase during postocclusive hyperemia (PORH(max) x t(1)(-1)) and during thermal hyperemia (TH(max) x t(2)(-1)) (P<.01) were accompanied by higher serum NAG activity (20.9+/-4.6 vs. 16.3+/-2.5 U l(-1), P<.01) in diabetic patients with microangiopathy as compared to healthy persons. An inverse relationship was found between PORH(max) x t(1)(-1) and NAG (r=-.33) results in diabetic patients. In addition, higher mean values of serum NAG activity, E-selectin, and ICAM-1 concentrations were associated with significantly lower values of microcirculation parameters (PORH(max) x t(2)(-1) and TH(max) x t(2)(-1)) in six patients without microangiopathy who had at least one of the above biochemical markers higher than mean+2 S.D. range. We suggest that serum NAG activity, E-selectin, and ICAM-1 concentrations may be used together with laser-Doppler flowmetry in Type 1 diabetic patients as early indicators of vascular changes in very early stage of diabetic microangiopathy.

Serum leptin levels in patients with primary hyperaldosteronism before and after treatment: relationships to insulin sensitivity

Background: Leptin is a protein hormone produced predominantly by adipocytes that plays a role in food intake regulation and a series of other physiological processes including blood pressure regulation.Objectives: The aim of our study was to compare serum leptin levels in patients with primary hyperaldosteronism (PA) with those of healthy subjects and to explore the relationship of serum leptin levels and the parameters of insulin action in these patients before and after surgical or pharmacological treatment.Methods: Serum potassium, leptin, aldosterone, insulin levels and plasma renin activity were measured and hyperinsulinaemic euglycaemic clamp was performed in 11 patients with PA and 11 healthy age-, gender- and body mass index (BMI)-matched subjects. In eight of 11 patients the same measurements were repeated at least 6 months after surgical or pharmacological treatment.Results: The basal serum leptin levels in PA patients did not significantly differ from those of healthy subjects (mean ± s.e.m. 8.4 ± 1.9 vs 11.2 ± 1.8 ng/ml, P = 0.30), although their insulin sensitivity was significantly impaired (PA patients vs control subjects: glucose disposal rate in the last 20 min of clamp (M) 18.7 ± 1.8 vs30.6 ± 3.3 μmol/kg/min, metabolic clearance rate of glucose (MCRg) 3.9 ± 0.5 vs7.2 ± 1.1 ml/kg/min, P < 0.05). The surgical or pharmacological treatment of PA patients increased significantly their serum leptin levels (10.9 ± 3.7 vs 8.4 ± 1.9 ng/ml, P < 0.05) and simultaneously improved their insulin sensitivity. Basal serum leptin levels in both groups correlated positively with BMI and serum insulin levels. The inverse relationship between serum leptin levels and the insulin sensitivity parameters was found in both PA patients before treatment and healthy subjects. These relationships disappeared after treatment of PA patients except for those between serum leptin levels and MCRg.Conclusion: Basal serum leptin levels in untreated patients with PA do not significantly differ from those of healthy subjects, but increase significantly after surgical or pharmacological treatment. The increase in serum leptin levels is paradoxically accompanied by the improvement of insulin sensitivity in these patients.

Serum α-tocopherol and ascorbic acid concentrations in Type 1 and Type 2 diabetic patients with and without angiopathy

BACKGROUND Alpha-tocopherol and ascorbic acid form a part of scavenger system influencing the level of oxidative stress in diabetes mellitus. The aim of this study was to evaluate serum concentrations of alpha-tocopherol and ascorbic acid in Type 1 and Type 2 diabetes mellitus and to compare them with the presence of vascular complications as well as with oxidative stress and endothelial dysfunction. METHODS A total of 38 Type 1 and 62 Type 2 diabetic patients were subdivided into those with and without angiopathy. Serum alpha-tocopherol and ascorbic acid concentrations were estimated in all patients and in 38 healthy persons. Their results were compared with diabetes control, with oxidative stress measured by plasma malondialdehyde and with endothelial dysfunction estimated by serum N-acetyl-beta-glucosaminidase activity. In addition, the differences in biochemical variables were compared between patients with and without angiopathy. RESULTS Serum alpha-tocopherol related to the sum of cholesterol and triglyceride concentrations (AT/CHT ratio) was significantly lower in diabetic patients with macroangiopathy than in those without vascular changes (p<0.05). Serum ascorbic acid levels were significantly lower only in Type 2 diabetic patients with macroangiopathy as compared with healthy controls as well as with patients without vascular disease (p<0.01). Positive relationship was observed between serum alpha-tocopherol and cholesterol or triglyceride concentrations in both Type 1 and Type 2 diabetic patients. The presence of oxidative stress together with endothelial dysfunction measured by N-acetyl-beta-glucosaminidase activity was accompanied by lower AT/CHT ratio (p<0.005) in Type 2 diabetic patients. CONCLUSION Diabetic patients with proven angiopathy or with advanced oxidative stress and endothelial dysfunction have significantly lower AT/CHT ratio and ascorbic acid concentration in serum. Their low concentrations may participate at the increased level of oxidative stress in these individuals.

2,3,7,8-TCDD exposure, endothelial dysfunction and impaired microvascular reactivity

Vascular function was examined in subjects with long-term high level of serum 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) during their follow-up visits. Their earlier mean peak TCDD level at the time of exposure in 1965—1968 was estimated in the range of 3300—74 000 pg/g lipids. Ten former pesticide production workers heavily exposed to TCDD (age 57 ± 2 years, TCDD about 170 pg/g lipids) were examined in 2001. Extended group of 15 TCDD-exposed men (age 59 ± 3 years, TCDD about 130 pg/g lipids) underwent the same examination in 2004. Findings were compared with a control group of 14 healthy men (age 54 ± 2 years). Skin microvascular reactivity (MVR) was measured by laser Doppler perfusion monitoring in the forearm during post-occlusive reactive hyperemia (PORH) and thermal hyperemia (TH). Several parameters of MVR in men exposed to TCDD were significantly impaired, compared with the control group and further progression of the impairment of MVR has been observed between years 2001 and 2004. Serum concentration of E-selectin and inhibitor of tissue plasminogen activator 1 (PAI-1) was significantly higher in exposed subjects (56.0 ± 18.4 ng/mL versus 40.0 ± 12.0 ng/mL, P = 0.022 and 90.9 ± 33.3 ng/mL versus 45.0 ± 18.0, P = 0.002, respectively). In addition, PORH in the forearm was significantly negatively associated with SOD activity (r = —0.77, P = 0.009) as well as the velocity of perfusion increase during TH (r = —0.68, P = 0.03) and TH% (r = —0.78, P = 0.008). Our data document the presence of endothelial dysfunction in TCDD-exposed men. Human & Experimental Toxicology (2007) 26, 705—713

Glucose variability, HbA1c and microvascular complications

Microvascular complications in diabetes are associated with poor long-term diabetes control as measured by HbA1c levels. Glucose fluctuations are related to oxidative stress, endothelial dysfunction, and inflammation, factors traditionally associated with the pathogenesis of vascular damage. Glucose variability has been associated with macrovascular disease in some studies but any association with microvascular disease remains controversial. This overview summarizes recent findings in the field of glucose variability and its possible relationship with retinopathy, nephropathy and neuropathy. It is concluded that randomized prospective follow-up trials could possibly help estimate whether short-term glucose variability should be considered as an independent risk factor for microvascular complications in diabetes.

Effect of glucose variability on pathways associated with glucotoxicity in diabetes: Evaluation of a novel in vitro experimental approach

AIMS Glycaemic variability (GV) has been hypothesized to increase the risk of diabetes complications; however, results of clinical studies are contradictory. The effect of GV on cell phenotypes has been investigated in vitro showing that GV may have more deleterious effect on cells that high glucose itself. However, methodology used to study GV in vitro differs significantly between studies and does not reflect in vivo situation. Therefore we aimed to establish clinically relevant an in vitro experimental approach for the study of GV that reflects intra-day glucose fluctuations of subjects with type 1 diabetes mellitus (T1DM) and of healthy subjects and to test how low and high GV affect expression of genes that protects cells from hyperglycaemia-induced damage. METHODS Human umbilical vein endothelial cells (HUVEC) were cultured 24h in medium with different glucose profiles: high GV, low GV and GV of healthy subjects-profiles created according to CGM of T1DM patients and healthy subjects. These profiles were compared to commonly used 5.5 and 25mmol/l glucose concentrations. Gene expression was determined using quantitative PCR. RESULTS Our results showed general down-regulation of enzymes that are involved in the protection against hyperglycaemia-induced intracellular changes in both low and high GV compared to normal glycaemia similarly to the decrease induced by continuous hyperglycaemia. Gene expressions did not differ between high and low GV. CONCLUSION Our data indicate that GV may have similar or even greater effect than continuous hyperglycaemia on the expression of several genes relevant to pathogenesis of diabetes microvascular complications.

Advances in the management of cardiovascular risk for patients with type 2 diabetes: perspectives from the Academy for Cardiovascular Risk, Outcomes and Safety Studies in Type 2 Diabetes

Diabetes is a global health emergency projected to affect 642 million people by 2040. Type 2 diabetes (T2D) represents 90% of diabetes cases and is associated with a range of cardiovascular (CV) risk factors that are more than double the incidence of CV disease and significantly increase mortality rates. Diabetes treatments have typically focused on improving glycemic control but their effect on CV outcomes has remained uncertain. In 2008, the US Food and Drug Administration (FDA) looked to address this knowledge gap and mandated CV outcome trials (CVOTs) for all new antidiabetic therapies. In 2015, EMPA-REG OUTCOME® became the first CVOT to present results for a sodium/glucose cotransporter 2 (SGLT2; also known as SLC5A2) inhibitor, empagliflozin. Subsequently, a regional meeting of the Academy for Cardiovascular Risk, Outcomes and Safety Studies in Type 2 Diabetes (ACROSS T2D) brought together a respected faculty of international experts and 150 physicians from 14 countries to discuss the current unmet medical needs of patients with T2D, the results from the EMPA-REG OUTCOME study and the implications of these results for clinical practice. This article summarizes the current scientific evidence and the discussions that took place at the ACROSS T2D regional meeting, which was held in Vienna, Austria, on May 30, 2016.

Translating recent results from the Cardiovascular Outcomes Trials into clinical practice: recommendations from the Central and Eastern European Diabetes Expert Group (CEEDEG)

AimsThese recommendations aim to improve care for patients with type 2 diabetes (T2D) at high cardiovascular (CV) risk in Central and Eastern Europe. Cardiovascular disease (CVD) and/or chronic kidney disease (CKD) are major interdependent comorbidities in patients with T2D, accounting for 50% of mortality. Following recent CV outcomes trial (CVOT) results, including those from EMPA-REG OUTCOME®, LEADER®, SUSTAIN™-6 and, most recently, the CANVAS study, it is essential to develop regional expert consensus recommendations to aid physicians in interpreting these newest data to clinical practice.MethodsThe Central and Eastern European Diabetes Expert Group (CEEDEG) followed a Delphi method to develop treatment algorithms to aid physicians in the clinical management of patients with T2D at high CV risk.ResultsIn light of the latest CVOT results, and in particular the EMPA-REG OUTCOME® and LEADER® trials, the diagnosis, assessment, treatment choice and monitoring of patients with T2D and established CVD and/or CKD have been considered together with existing guidelines and presented in two reference algorithms. In addition, adherence, special prescribing considerations and a proposed multidisciplinary management approach have been discussed and are presented with the proposed algorithms.ConclusionsThe latest available high-level evidence on glucose-lowering drugs has enabled CEEDEG to develop practical consensus recommendations for patients with established CVD and/or CKD. These recommendations represent an update to international and country-level guidelines used for these patients, with the aim of providing a resource not only to endocrinologists, but to cardiologists, nephrologists and primary care physicians in the region.

Acute Hyperglycemia Does Not Impair Microvascular Reactivity and Endothelial Function during Hyperinsulinemic Isoglycemic and Hyperglycemic Clamp in Type 1 Diabetic Patients

Aims. The aim of this study was to evaluate the effect of acute glycemia increase on microvasculature and endothelium in Type 1 diabetes during hyperinsulinemic clamp. Patients and Methods. Sixteen patients (51 ± 7 yrs) without complications were examined during iso- and hyperglycemic clamp (glucose increase 5.5 mmol·L−1). Insulin, lipid parameters, cell adhesion molecules and fibrinogen were analyzed. Microvascular reactivity (MVR) was measured by laser Doppler flowmetry. Results. Maximum perfusion and the velocity of perfusion increase during PORH were higher in hyperglycemia compared to baseline (47 ± 16 versus 40 ± 16 PU, P < 0.01, and 10.4 ± 16.5 versus 2.6 ± 1.5 PU·s−1, P < 0.05, resp.). Time to the maximum perfusion during TH was shorter and velocity of perfusion increase during TH higher at hyperglycemia compared to isoglycemic phase (69 ± 15 versus 77 ± 16 s, P < 0.05, and 1.4 ± 0.8 versus 1.2 ± 0.7 PU·s−1, P < 0.05, resp.). An inverse relationship was found between insulinemia and the time to maximum perfusion during PORH (r = −0.70, P = 0.007). Conclusion. Acute glycemia did not impair microvascular reactivity in this clamp study in Type 1 diabetic patients. Our results suggest that insulin may play a significant role in the regulation of microvascular perfusion in patients with Type 1 diabetes through its vasodilation effect and can counteract the effect of acute glucose fluctuations.

Relevance of positive cardiovascular outcome trial results in clinical practice: perspectives from the Academy for Cardiovascular Risk, Outcomes and Safety Studies in Type 2 Diabetes (ACROSS T2D)

Type 2 diabetes (T2D) imposes a substantial disease burden, predominantly from cardiovascular disease (CVD), which accounts for >50% of deaths in this population and leads to a 12-year reduction in the life expectancy of a 60-year-old male patient with T2D and CVD compared with the general population. The results from mandatory cardiovascular outcome trials (CVOTs) are therefore of great interest in the field. The Academy for Cardiovascular Risk, Outcomes and Safety Studies in Type 2 Diabetes meeting program aims to bring together experts from several associated disciplines to provide fair and balanced resources for those involved in the management of patients with T2D. This publication represents the opinions of the faculty on the key learnings from the meeting held in Vienna in the spring of 2017. In particular, we detail how data from the EMPA-REG OUTCOME® [cardiovascular outcomes trial of empagliflozin] and Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results (LEADER®) (liraglutide) CVOTs can be practically interpreted across clinical specialities. It is hoped that this translation of CVOT data will achieve a dual treatment paradigm for the management of both raised glucose levels and CV risk in patients with T2D.