Vessel wall stiffness in type 1 diabetes and the central hemodynamic effects of acute hypoglycemia

Hypoglycemia and Cardiovascular Disease: Exploring the Connections

It has long been known that administering insulin or insulin secretagogues to treat diabetes has the unfavorable side effect of hypoglycemia. Because hypoglycemia can disrupt normal brain function, it can have a profound impact on people's lives. Studies have shown a connection between hypoglycemia and a higher risk of death and cardiovascular disease. Through experimental studies, numerous potential reasons for the start of cardiovascular events have been discovered. In addition, studies on people have demonstrated that hypoglycemia can result in ventricular arrhythmias. According to recent studies, a number of factors may affect the relationship between hypoglycemia, cardiovascular events, and mortality. Confounding factors may explain the apparent correlation, at least in part. People with comorbidities may experience more hypoglycemia, increasing their risk of mortality. Those who have type 1 or type 2 diabetes, however, seem to be more susceptible to the negative effects of hypoglycemia on the cardiovascular system. When choosing appropriate glucose-lowering treatments and setting glycemic objectives with patients, clinicians should be aware of this risk.

Association of hypoglycaemia with the risks of arrhythmia and mortality in individuals with diabetes - a systematic review and meta-analysis

Background

Hypoglycaemia has been linked to an increased risk of cardiac arrhythmias by causing autonomic and metabolic alterations, which may be associated with detrimental outcomes in individuals with diabetes(IWD), such as cardiovascular diseases (CVDs) and mortality, especially in multimorbid or frail people. However, such relationships in this population have not been thoroughly investigated. For this reason, we conducted a systematic review and meta-analysis.

Methods

Relevant papers published on PubMed, Embase, Cochrane, Web of Knowledge, Scopus, and CINHAL complete from inception to December 22, 2022 were routinely searched without regard for language. All of the selected articles included odds ratio, hazard ratio, or relative risk statistics, as well as data for estimating the connection of hypoglycaemia with cardiac arrhythmia, CVD-induced death, or total death in IWD. Regardless of the heterogeneity assessed by the I2 statistic, pooled relative risks (RRs) and 95% confidence intervals (CI) were obtained using random-effects models.

Results

After deleting duplicates and closely evaluating all screened citations, we chose 60 studies with totally 5,960,224 participants for this analysis. Fourteen studies were included in the arrhythmia risk analysis, and 50 in the analysis of all-cause mortality. Hypoglycaemic patients had significantly higher risks of arrhythmia occurrence (RR 1.42, 95%CI 1.21-1.68), CVD-induced death (RR 1.59, 95% CI 1.24-2.04), and all-cause mortality (RR 1.68, 95% CI 1.49-1.90) compared to euglycaemic patients with significant heterogeneity.

Conclusion

Hypoglycaemic individuals are more susceptible to develop cardiac arrhythmias and die, but evidence of potential causal linkages beyond statistical associations must await proof by additional specifically well planned research that controls for all potential remaining confounding factors.

Effects of Hypoglycemia on Cardiovascular Function in Patients with Diabetes

Hypoglycemia is common in patients with type 1 and type 2 diabetes (T1D, T2D), treated with insulin or sulfonylureas, and has multiple short- and long-term clinical implications. Whether acute or recurrent, hypoglycemia significantly affects the cardiovascular system with the potential to cause cardiovascular dysfunction. Several pathophysiological mechanisms have been proposed linking hypoglycemia to increased cardiovascular risk, including hemodynamic changes, myocardial ischemia, abnormal cardiac repolarization, cardiac arrhythmias, prothrombotic and proinflammatory effects, and induction of oxidative stress. Hypoglycemia-induced changes can promote the development of endothelial dysfunction, which is an early marker of atherosclerosis. Although data from clinical trials and real-world studies suggest an association between hypoglycemia and cardiovascular events in patients with diabetes, it remains uncertain whether this association is causal. New therapeutic agents for patients with T2D do not cause hypoglycemia and have cardioprotective benefits, whereas increasing the use of new technologies, such as continuous glucose monitoring devices and insulin pumps, has the potential to reduce hypoglycemia and its adverse cardiovascular outcomes in patients with T1D.

Glucose-Lowering and the Risk of Cardiovascular Events With Antidiabetic Therapies: A Systematic Review and Additive-Effects Network Meta-Analysis

Aim

To assess the impact of the HbA1c levels achieved with antidiabetic therapies (ADTs) on the risk of MACE.

Methods

A systematic search was performed in PubMed, Cochrane, and ClinicalTrials. gov for RCTs published up to March 2022 reporting the occurrence of MACE and all-cause mortality in individuals with T2DM treated with all marketed ADTs, including a sample size ≥100 individuals in each study arm and follow-up ≥24 weeks. A systematic review and additive-effects network meta-analysis with random effects and a multivariate meta-regression were utilized to assess the impact of achieved HbA1c on incident MACE.

Results

We included 126 RCTs with 143 treatment arms, 270,874 individuals, and 740,295 individuals-years who were randomized to an active treatment vs. control group. Among all ADTs, only therapy with SGLT2i, GLP1-RA, or pioglitazone similarly reduced the risk of MACE compared to placebo. The achievement of HbA1c ≤ 7.0% in RCTs with the 3 drug classes in the active arm was associated with an adjusted HR of 0.91 (95% CI 0.80, 0.97; p = 0.017) compared with HbA1c>7.0%, without affecting all-cause mortality. These results, however, were not maintained among all ADTs.

Conclusions

Achieving lower glucose levels with SGLT2i, GLP1-RA, or pioglitazone is linearly associated with a reduced risk of MACEs, without affecting all-cause mortality.

Systematic Review Registration

www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020213127, identifier: CRD42020213127.

Severe Hypoglycemia Increases Dementia Risk and Related Mortality: A Nationwide, Population-based Cohort Study

CONTEXT

There are few studies focused on the relationship between hypoglycemia and new-onset dementia in patients with type 2 diabetes and no study regarding mortality of dementia after hypoglycemia.

OBJECTIVE

We investigated the effect of severe hypoglycemia on dementia subtypes and its relation to overall mortality in patients with type 2 diabetes.

METHODS

We evaluated incident dementia, including Alzheimer disease and vascular dementia, among health checkup participants aged 40 years or older in the National Health Insurance System in Korea from January 2009 to December 2015. Episodes of severe hypoglycemia were examined for 3 years before the date of the health checkup.

RESULTS

Among 2 032 689 participants (1 172 271 men, 860 418 women), 14 443 (0.7%) experienced severe hypoglycemia, during a mean follow-up period of 6.9 ± 1.7 years. Individuals in the severe hypoglycemia group were more likely to be diagnosed with dementia compared to individuals without severe hypoglycemia (23.3% vs 7.3%; P < .001) and the overall incidence of Alzheimer disease was higher than vascular dementia. Dementia risk rose with increasing number of severe hypoglycemic episodes (1 episode [hazard ratio (HR) = 1.54; 95% CI, 1.48-1.60], 2 or more episodes [HR = 1.80; 95% CI, 1.66-1.94]). Overall mortality was higher in participants with dementia, but without severe hypoglycemia (HR = 2.03; 95% CI, 1.96-2.10) and severe hypoglycemia, but without dementia (HR = 4.24; 95% CI, 4.29-4.40), and risk of death was highest in those with both severe hypoglycemia and dementia (HR = 5.08; 95% CI, 4.83-5.35).

CONCLUSION

Severe hypoglycemia is associated with dementia, especially Alzheimer disease and mortality; together, they have an additive effect on overall mortality.

Current trends in epidemiology of cardiovascular disease and cardiovascular risk management in type 2 diabetes

With the advances in diabetes care, the trend of incident cardiovascular disease (CVD) in patients with type 2 diabetes mellitus (T2DM) has been decreasing over past decades. However, given that CVD is still a major cause of death in patients with diabetes and that the risk of CVD in patients with T2DM is more than twice that in those without DM, there are still considerable challenges to the prevention of CVD in diabetes. Accordingly, there have been several research efforts to decrease cardiovascular (CV) risk in T2DM. Large-scale genome-wide association studies (GWAS) and clinical cohort studies have investigated the effects of factors, such as genetic determinants, hypoglycaemia, and insulin resistance, on CVD and can account for the unexplained CV risk in T2DM. Lifestyle modification is a widely accepted cornerstone method to prevent CVD as the first-line strategy in T2DM. Recent reports from large CV outcome trials have proven the positive CV effects of sodium-glucose cotransporter-2 (SGLT-2) inhibitors and glucagon-like peptide-1 receptor agonists (GLP-1RAs) in patients with high CVD risk. Overall, current practice guidelines for the management of CVD in T2DM are moving from a glucocentric strategy to a more individualised patient-centred approach. This review will discuss the current epidemiologic trends of CVD in T2DM and the risk factors linking T2DM to CVD, including genetic contribution, hypoglycaemia, and insulin resistance, and proper care strategies, including lifestyle and therapeutic approaches.

Glucagon as a Therapeutic Approach to Severe Hypoglycemia: After 100 Years, Is It Still the Antidote of Insulin?

Hypoglycemia represents a dark and tormented side of diabetes mellitus therapy. Patients treated with insulin or drug inducing hypoglycemia, consider hypoglycemia as a harmful element, which leads to their resistance and lack of acceptance of the pathology and relative therapies. Severe hypoglycemia, in itself, is a risk for patients and relatives. The possibility to have novel strategies and scientific knowledge concerning hypoglycemia could represent an enormous benefit. Novel available glucagon formulations, even now, allow clinicians to deal with hypoglycemia differently with respect to past years. Novel scientific evidence leads to advances concerning physiopathological mechanisms that regulated glycemic homeostasis. In this review, we will try to show some of the important aspects of this field.

History of Severe Hypoglycemia in Type 2 Diabetes Mellitus Unmasked Significant Atherosclerotic Coronary Artery Disease: A Comparative Case Control Study

Objectives

A history of severe hypoglycemia (SH) is associated with cardiovascular (CV) events among patients with type 2 diabetes mellitus (T2DM). In this study, we compared the severity of atherosclerotic coronary artery disease (ACAD) in T2DM patients with and without a history of SH.

Methodology

We conducted a comparative case-control study involving 28 T2DM patients with a history of SH within the last 5 years with no documented ACAD, and matched them with 28 T2DM patients with no history of SH. All subjects underwent coronary artery calcium scoring (CACS) with or without coronary computed tomographic angiography (CCTA) to evaluate the severity of ACAD.

Results

A history of SH in T2DM was associated with a higher prevalence of significant ACAD (79% versus 46%, p=0.026). A high CACS (≥100) was seen in a greater number of patients with a history of SH compared to those without (75% versus 43%, p=0.029). Similarly, there was a higher prevalence of obstructive CAD in those with a history of SH compared to those without (72% versus 39%, p=0.036). Median C-reactive protein level was also higher among patients with a history of SH (0.41 mg/dL versus 0.16 mg/dL, p=0.029).

Conclusion

In patients with T2DM, a history of SH is significantly associated with ACAD compared to those without SH. A history of SH warrants screening for ACAD.

Characteristics of patients with hypertension in a population with type 2 diabetes mellitus. Results from the Turkish Nationwide SurvEy of Glycemic and Other Metabolic Parameters of Patients with Diabetes Mellitus (TEMD Hypertension Study)

BACKGROUND

The present survey aimed to find out the demographical and clinical characteristics of patients with hypertension in a population with type 2 diabetes mellitus (T2DM) in Turkey.

METHODS

Patients with T2DM who were followed-up in tertiary endocrine units for at least last one year were recruited. Demographic, clinical and biochemical data of the patients were collected. Hypertension was defined as taking anti-hypertensive medications or having office arterial blood pressure (ABP) ≥140/90 mmHg or home ABP ≥ 130/80 mmHg.

RESULTS

A total of 4756 (58.9% women) diabetic patients were evaluated. The percentage of patients with hypertension was 67.5% (n = 3212). Although 87.4% (n = 2808) of hypertensive patients were under treatment, blood pressure was on target in 52.7% (n = 1479) of patients. Hypertension proportions were higher in woman (p = 0.001), older, more obese, and those who had longer diabetes duration, lower education levels, higher frequency of hypoglycemic events (all p < 0.001) and higher triglyceride levels (p = 0.003). LDL cholesterol level and the percentage of smokers were lower in hypertensive group than in non-hypertensive group (both p < 0.001). The percentage of macro and microvascular complications was higher in the hypertensive group than in the normotensive one (both p < 0.001). In multivariate logistic regression analysis, being a woman (OR: 1.26, 95% CI: 1.04-1.51, p = 0.016), smoking (OR: 1.38, 95% CI: 1.05-1.80, p = 0.020), regular physical activity (OR: 1.24, 95% CI: 1.01-1.53, p = 0.039) and the presence of macrovascular complications (OR: 1.38 95% CI: 1.15-1.65, p = 0.001) were the significant predictors of good ABP regulation. The ratios of masked and white coat hypertension were 41.2% and 5.7%, respectively.

CONCLUSION

Our findings indicate that two-thirds (67.5%) of adult patients with T2DM have hypertension. Co-existence of hypertension increases the frequency of macro and microvascular diabetic complications in these patients. Despite the critical role of hypertension in morbidity and mortality, only half of the patients have favorable ABP levels. Masked hypertension seems to be another important issue in this population.

Severe hypoglycemia and the risk of end stage renal disease in type 2 diabetes

We investigated the association between the incidence of severe hypoglycemia and the risk of end-stage renal disease (ESRD) in patients with type 2 diabetes. Baseline and follow-up data for 988,333 participants with type 2 diabetes were retrieved from the National Health Insurance System database. The number of severe hypoglycemia episodes experienced from 2007 to 2009 was determined. The primary outcome was the development of ESRD after the baseline evaluation. Participants were followed from the baseline until death or December 31, 2016, during this period 14,545 participants (1.5%) developed ESRD. In the crude model, compared with those who experienced no severe hypoglycemia, the hazard ratios (95% confidential intervals) for developing ESRD were 4.96 (4.57–5.39), 6.84 (5.62–8.32), and 9.51 (7.14–12.66) in participants who experienced one, two, and three or more episodes of severe hypoglycemia, respectively. Further adjustment for various confounding factors attenuated the association between severe hypoglycemia and ESRD; the significance of the association between severe hypoglycemia and ESRD was maintained. Having three or more severe hypoglycemia episodes was associated with a nearly two-fold increased risk of developing ESRD. Prior episodes of severe hypoglycemia were associated with an increased risk of ESRD among Korean adults with type 2 diabetes.

Hypoglycemia in the emergency, is there any effect on endothelial and diastolic functions?

INTRODUCTION

Several homeostatic changes like an increase in sympathoadrenal response and oxidative stress occur in hypoglycemia. As a result of these findings, an increase in inflammation and preatherogenic factors is observed, and these changes may lead to endothelial dysfunction.

AIM

Our study aims to reveal possible cardiac risks (systolic-diastolic functions and endothelial dysfunctions) in patients who have applied to the emergency department with hypoglycemia.

METHODS

This cross-sectional, case-control study included 46 hypoglycemia patients who admitted to the emergency with symptoms compatible with hypoglycemia and diagnosed with hypoglycemia and 30 healthy volunteers. All patients were evaluated with baseline echocardiography, tissue-Doppler imaging (carotid and brachial artery). Also, the fasting blood tests of the patients referred to the internal medicine department were examined.

RESULTS

There were no differences between the groups regarding age, weight, body mass index, and systolic blood pressure. Total cholesterol, LDL, HDL, Vitamin B12, TSH, and fasting blood glucose levels were similar in the groups' blood tests (all P values > .05). We observed a statistically significant decrease in diastolic dysfunction parameters: E/A and E/e' ratios (respectively, P = .020 and 0.026). It was shown that insulin resistance was influential in forming these considerable differences. The patient group observed that the carotid intima-media thickness was more remarkable (P = .001), and the brachial flow-mediated dilatation value was smaller (P = .003), giving an idea about endothelial functions.

CONCLUSION

As a message, we can say that hypoglycemia may affect diastolic functions in addition to endothelial dysfunction. Therefore, even young individuals without any chronic diseases may need follow-up in terms of possible risks.

Severe hypoglycemia and the risk of cardiovascular disease and mortality in type 2 diabetes: a nationwide population-based cohort study

BACKGROUND

We investigated the association regarding severe hypoglycemia episodes with cardiovascular disease risk and all-cause mortality in patients with type 2 diabetes.

METHODS

Baseline and follow-up data (n = 1,568,097) from patients with type 2 diabetes were retrieved from the National Health Insurance System database (covering the entire Korean population). Type 2 diabetes, severe hypoglycemia, and major comorbidities were identified using International Classification of Diseases 10 codes and medication information. Individuals who were classified as type 2 diabetes in the year of 2009 were screened, and we counted severe hypoglycemia episodes from 2007 to 2009. The primary outcome was newly developed myocardial infarction (MI), stroke, heart failure, or all-cause mortality. Participants were followed from the baseline index date to the date of death or until December 31, 2015.

RESULTS

In total, 19,660 (1.2%) patients developed at least one severe hypoglycemia event during the period from 2007 to 2009. Mean follow-up was 5.7 years. After adjustment for confounding factors, the hazard ratio (HR) of MI significantly and sequentially increased: 0 vs. 1 episode, HR 1.56, 95% CI 1.46-1.64; 0 vs. 2 episodes, HR 1.86, 95% CI 1.61-2.15; 0 vs. 3 or more episodes, HR 1.86, 95% CI 1.48-2.35, P for trend < 0.001. Similar findings were noted regarding the relationship of severe hypoglycemia episodes with stroke, heart failure, and all-cause mortality. Risks for all outcomes were highest within 1 year from the index date and showed decreasing trends with follow-up. Sensitivity analyses of the data from the subgroup population and 797,544 subjects who received a national health examination did not change the significance of the main findings.

CONCLUSION

Among adult Korean patients with type 2 diabetes, a severe hypoglycemia episode is associated with increased risk for cardiovascular outcomes and all-cause mortality. Significant results from dose-response, temporal, and sensitivity analyses may suggest the possibility of direct causality between severe hypoglycemia and cardiovascular outcomes and mortality.

Early cardiovascular risk and all-cause mortality following an incident of severe hypoglycaemia: A population-based cohort study

AIMS

Severe hypoglycaemia is associated with a high risk of cardiovascular events in patient with diabetes. The aim of this study was to clarify the temporal relationship between hypoglycaemia and cardiovascular events.

MATERIALS AND METHODS

This observational cohort study was conducted using Taiwan's Longitudinal Cohort of Diabetes Patients Database, which included 360 000 patients with newly diagnosed diabetes during the period 1999 to 2001. Patients with the first severe hypoglycaemia after 2002 served as the study cohort. Each patient in the study cohort was matched with two control patients without severe hypoglycaemia, based on a propensity score. A joinpoint regression model was used to determine trends in all-cause mortality and incidence of cardiovascular disease (CVD) events in both cohorts.

RESULTS

A total of 10 157 patients with severe hypoglycaemia and 20 314 matched controls were recruited. Patients with severe hypoglycaemia had a significantly higher risk of CVD (HR, 7.28; 95% CI, 5.19-10.20) and all-cause mortality (HR, 19.92; 95% CI, 13.42-29.56) during the first month compared with those without. In patients with severe hypoglycaemia, the incidence of CVDs dropped by 17.29% monthly during the first 4 months and slowly decreased (-0.67%) during subsequent months. All-cause mortality decreased by 16.55% and 3.24% monthly during months 0-6 and months 6-17, respectively.

CONCLUSIONS

Severe hypoglycaemia is associated with a greater risk of cardiovascular events and death, especially during the first month following a hypoglycaemic episode. Patients prone to severe hypoglycaemia should be made aware of the elevated risk of subsequent cardiovascular events.

Hypoglycaemia, cardiovascular disease, and mortality in diabetes: epidemiology, pathogenesis, and management

Hypoglycaemia has long been recognised as a dangerous side-effect of treatment of diabetes with insulin or insulin secretagogues. With its potential to disrupt cerebral function, hypoglycaemia can have a major effect on peoples' lives. Study findings have suggested that hypoglycaemia is associated with an increased risk of cardiovascular events and mortality. Different mechanisms by which hypoglycaemia might provoke cardiovascular events have been identified in experimental studies, and in clinical studies cardiac arrhythmias have been reported to be induced by hypoglycaemia, with one report describing sudden death during a severe episode. Emerging evidence suggests that the association between hypoglycaemia and cardiovascular events and mortality is likely to be multifactorial. The association is probably partly caused by confounding, with hypoglycaemia occurring more frequently in people with comorbidities who are also more likely to die than those without. However, people with type 1 or type 2 diabetes also seem at risk of hypoglycaemia-induced cardiovascular effects. This risk should be recognised by clinicians when agreeing glycaemic goals with patients and choosing appropriate glucose-lowering therapies.

Ultrasonographic Evaluation of Glycemic Control Effect on Placental Vascularization in Pregnancy with Type 1 Diabetes Mellitus

AIMS

The aim of our study was to assess the effect of glycemic control on placental vascularization in pregnancies complicated by type 1 diabetes mellitus (T1DM) and to compare dataset of optimal/suboptimal glycemic control to normal placental 3-dimensional power Doppler (3-DPD) indices in 2^nd and 3^rd trimester.

METHODS

Placental vascularization of pregnant women was prospectively evaluated by 3-DPD ((vascularization-index (VI); flow-index (FI); vascularization-flow-index (VFI)) ultrasound technique. The normal pregnancies (n=214) were compared to those complicated by T1DM (n=53) with optimal (HbA1C≤6%;≤ 42 mmol/mol) and suboptimal (HbA1C>6%;>42 mmol/mol) glycemic control.

RESULTS

Pregnancies complicated by T1DM expressed lower placental vascularization indices as compared with normal pregnancies (adjusted odds ratio (AOR) for VI:0.86; FI:0.94; VFI:0.76). Placental 3-DPD indices have a significant correlation with HbA1C and optimal glycemic control is associated with lower placental perfusion (AOR for VI:1.64; FI:1.13; VFI:2.34). Short-term adverse neonatal outcome was predicted by lower 3-DPD indices (AOR_VI:0.83, AOR_FI:0.93, AOR_VFI:0.66, p<0.05 for each index). Besides the glycemic control, the pregestational body mass index (BMI), had significant influences on placental perfusion.

CONCLUSIONS

VI displayed the best screening ability for suboptimal glycemic control with a sensitivity of 90.9%. The suboptimal glycemic control has a direct deteriorating effect on placental vasculature. Therefore the ultrasound examination could be an adjunct diagnostic modality for pregnant women with T1DM.

DEVOTE 3: temporal relationships between severe hypoglycaemia, cardiovascular outcomes and mortality

AIMS/HYPOTHESIS

The double-blind Trial Comparing Cardiovascular Safety of Insulin Degludec vs Insulin Glargine in Patients with Type 2 Diabetes at High Risk of Cardiovascular Events (DEVOTE) assessed the cardiovascular safety of insulin degludec. The incidence and rates of adjudicated severe hypoglycaemia, and all-cause mortality were also determined. This paper reports a secondary analysis investigating associations of severe hypoglycaemia with cardiovascular outcomes and mortality.

METHODS

In DEVOTE, patients with type 2 diabetes were randomised to receive either insulin degludec or insulin glargine U100 (100 units/ml) once daily (between dinner and bedtime) in an event-driven, double-blind, treat-to-target cardiovascular outcomes trial. The primary outcome was the first occurrence of an adjudicated major adverse cardiovascular event (MACE; cardiovascular death, non-fatal myocardial infarction or non-fatal stroke). Adjudicated severe hypoglycaemia was the pre-specified secondary outcome. In the present analysis, the associations of severe hypoglycaemia with both MACE and all-cause mortality was evaluated in the pooled trial population using time-to-event analyses, with severe hypoglycaemia as a time-dependent variable and randomised treatment as a fixed factor. An investigation with interaction terms indicated that the effect of severe hypoglycaemia on the risk of MACE and all-cause mortality were the same for both treatment arms, and so the temporal association for severe hypoglycaemia with subsequent MACE and all-cause mortality is reported for the pooled population.

RESULTS

There was a non-significant difference in the risk of MACE for individuals who had vs those who had not experienced severe hypoglycaemia during the trial (HR 1.38, 95% CI 0.96, 1.96; p = 0.080) and therefore there was no temporal relationship between severe hypoglycaemia and MACE. There was a significantly higher risk of all-cause mortality for patients who had vs those who had not experienced severe hypoglycaemia during the trial (HR 2.51, 95% CI 1.79, 3.50; p < 0.001). There was a higher risk of all-cause mortality 15, 30, 60, 90, 180 and 365 days after experiencing severe hypoglycaemia compared with not experiencing severe hypoglycaemia in the same time interval. The association between severe hypoglycaemia and all-cause mortality was maintained after adjustment for the following baseline characteristics: age, sex, HbA1c, BMI, diabetes duration, insulin regimen, hepatic impairment, renal status and cardiovascular risk group.

CONCLUSIONS/INTERPRETATION

The results from these analyses demonstrate an association between severe hypoglycaemia and all-cause mortality. Furthermore, they indicate that patients who experienced severe hypoglycaemia were particularly at greater risk of death in the short term after the hypoglycaemic episode. These findings indicate that severe hypoglycaemia is associated with higher subsequent mortality; however, they cannot answer the question as to whether severe hypoglycaemia serves as a risk marker for adverse outcomes or whether there is a direct causal effect.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01959529.

Potential link between post-acute ischemic stroke exposure to hypoglycemia and hemorrhagic transformation

Hemorrhagic transformation is a severe complication of acute ischemic stroke owing to its limited treatment options and poor prognosis. In the last decade, the rates of hemorrhagic transformation incidence have been associated with blood glucose levels. In particular, hyperglycemia at the time of admission has been associated with increased rates of hemorrhagic transformation in acute ischemic stroke patients. Recent pilot clinical trials have attempted to use intensive insulin therapy during stroke treatment to reduce the severity of cerebral infarction and possibly alleviate the risk of hemorrhagic transformation. However, the results of these studies have shown no clear clinical benefit. In addition, intensive insulin therapy has increased rates of hypoglycemia which may be associated with larger infarct growth. We hypothesize that hypoglycemia, similarly to hyperglycemia, is a risk factor for worse outcomes in acute ischemic stroke by promoting hemorrhagic transformation. This review serves to call attention to patterns present within intensive insulin therapy trials and shed light into the pathophysiological effects of hypoglycemia. It is critical that efforts be directed toward the prevention of hemorrhagic transformation by optimizing insulin therapy during the treatment of acute ischemic stroke.

Low glucose induces mitochondrial reactive oxygen species via fatty acid oxidation in bovine aortic endothelial cells

AIMS/INTRODUCTION

Overproduction of reactive oxygen species (ROS) in endothelial cells (ECs) plays a pivotal role in endothelial dysfunction. Mitochondrial ROS (mtROS) is one of the key players in the pathogenesis of diabetic vascular complications. Hypoglycemia is linked to increased ROS production and vascular events; however, the underlying mechanisms remain unclear. In the present study, we aimed to determine whether and how low glucose (LG) mediates mtROS generation in ECs, and to examine the impact of LG-induced mtROS on endothelial dysfunction.

MATERIALS AND METHODS

Metabolomic profiling, cellular oxygen consumption rate, mtROS, endothelial nitric oxide synthase phosphorylation, and the expression of vascular cell adhesion molecule-1 or intercellular adhesion molecule-1 were evaluated in bovine aortic ECs.

RESULTS

We found that LG increased mtROS generation in ECs; which was suppressed by overexpression of manganese superoxide dismutase. Comprehensive metabolic analysis using capillary electrophoresis-mass spectrometry and oxygen consumption rate assessment showed that the pathway from fatty acid to acetyl-CoA through fatty acid oxidation was upregulated in ECs under LG conditions. In addition, etomoxir, a specific inhibitor of the free fatty acid transporter, decreased LG-induced mtROS production. These results suggested that LG increased mtROS generation through activation of fatty acid oxidation. We further revealed that LG inhibited endothelial nitric oxide synthase phosphorylation, and increased the expression of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1. These effects were suppressed either by overexpression of manganese superoxide dismutase or by treatment with etomoxir.

CONCLUSIONS

The activation of fatty acid oxidation followed by mtROS production could be one of the causes for endothelial dysfunction during hypoglycemia.

Dynamin-related protein 1 mediates low glucose-induced endothelial dysfunction in human arterioles

Intensive glycemic regulation has resulted in an increased incidence of hypoglycemia. Hypoglycemic burden correlates with adverse cardiovascular complications and contributes acutely and chronically to endothelial dysfunction. Prior data indicate that mitochondrial dysfunction contributes to hypoglycemia-induced endothelial dysfunction, but the mechanisms behind this linkage remain unknown. We attempt to determine whether clinically relevant low-glucose (LG) exposures acutely induce endothelial dysfunction through activation of the mitochondrial fission process. Characterization of mitochondrial morphology was carried out in cultured endothelial cells by using confocal microscopy. Isolated human arterioles were used to explore the effect LG-induced mitochondrial fission has on the formation of detrimental reactive oxygen species (ROS), bioavailability of nitric oxide (NO), and endothelial-dependent vascular relaxation. Fluorescence microscopy was employed to visualize changes in mitochondrial ROS and NO levels and videomicroscopy applied to measure vasodilation response. Pharmacological disruption of the profission protein Drp1 with Mdivi-1 during LG exposure reduced mitochondrial fragmentation among vascular endothelial cells (LG: 0.469; LG+Mdivi-1: 0.276; P = 0.003), prevented formation of vascular ROS (LG: 2.036; LG+Mdivi-1: 1.774; P = 0.005), increased the presence of NO (LG: 1.352; LG+Mdivi-1: 1.502; P = 0.048), and improved vascular dilation response to acetylcholine (LG: 31.6%; LG+Mdivi-1; 78.5% at maximum dose; P < 0.001). Additionally, decreased expression of Drp1 via siRNA knockdown during LG conditions also improved vascular relaxation. Exposure to LG imparts endothelial dysfunction coupled with altered mitochondrial phenotypes among isolated human arterioles. Disruption of Drp1 and subsequent mitochondrial fragmentation events prevents impaired vascular dilation, restores mitochondrial phenotype, and implicates mitochondrial fission as a primary mediator of LG-induced endothelial dysfunction.NEW & NOTEWORTHY Acute low-glucose exposure induces mitochondrial fragmentation in endothelial cells via Drp1 and is associated with impaired endothelial function in human arterioles. Targeting of Drp1 prevents fragmentation, improves vasofunction, and may provide a therapeutic target for improving cardiovascular complications among diabetics.Listen to this article's corresponding podcast @ http://ajpheart.podbean.com/e/mitochondrial-dynamics-impact-endothelial-function/.

Risk Factors and Adverse Outcomes of Severe Hypoglycemia in Type 2 Diabetes Mellitus

Hypoglycemia has been considered as a major barrier to achieving the proper glycemic target in type 2 diabetes mellitus patients. In particular, severe hypoglycemia (SH), which is defined as a hypoglycemic episode requiring the assistance of another person to raise the patient's glucose level, is a serious complication of diabetes because of its possible fatal outcomes. Recently, the recommendations for diabetes care have emphasized a patient-centered approach, considering the individualized patient factors including hypoglycemia. Many studies have been performed which analyzed the risk factors and clinical outcomes for SH. From the studies, researchers recommend that targeting a less stringent glycosylated hemoglobin level and selecting a safer class of drugs for hypoglycemia are appropriate for patients with a high risk of SH. Also, careful clinical attention to prevent hypoglycemia, including intensive education, is necessary to minimize the risk of SH and SH-related fatal outcomes.

Glucose Control and Vascular Outcomes in Type 2 Diabetes: Is the Picture Clear?

The overall impact of glucose lowering on vascular complications and major clinical outcomes, including mortality, in type 2 diabetes is still an open issue. While intensive glucose control has undoubted benefit for microvascular end points, the relationship between glucose-lowering approaches and reduced incidence and/or progression of macrovascular complications is less clear. This review article will discuss the effect of glucose lowering per se as well as the effects of specific glucose-lowering therapies on vascular outcomes in type 2 diabetes. The role of lifestyle changes on cardiovascular outcomes will be also addressed. Recent analyses from large cardiovascular outcome studies (ACCORD, ADVANCE, and VADT) provide new information on factors that modulate the impact of intensive glucose lowering on outcomes, helping to identify the specific clinical characteristics of the patients receiving the intervention that would show a better response. While several studies on cardiovascular outcomes with diabetes drugs are available, they do not clearly highlight a benefit from using a specific medication or will require additional evidence, as for the sodium-glucose cotransporter 2 blockers.

Hypoglycemia and Cardiovascular Risk: Is There a Major Link?

Severe hypoglycemia is recognized to be one of the strongest predictors of macrovascular events, adverse clinical outcomes, and mortality in patients with type 2 diabetes. However, it is uncertain whether a direct pathophysiological link exists or whether hypoglycemia is primarily a marker of vulnerability to these events. Large clinical trials have reported an increased hazard ratio for all-cause mortality and cardiovascular events in patients with type 2 diabetes and severe hypoglycemia, but such an association has not been demonstrated in prospective trials of people with type 1 diabetes. Several cardiovascular effects occur during hypoglycemia either as a result of low blood glucose levels per se or through activation of the sympathoadrenal response: hemodynamic changes with an increase in cardiac work load and potential attenuation of myocardial perfusion, electrophysiological changes that may be arrhythmogenic, induction of a prothrombotic state, and release of inflammatory markers. Although the potential for a causal relationship has been demonstrated in mechanistic studies, the evidence from large prospective studies that hypoglycemia is a major causal contributor to cardiovascular events is limited to date. Other preexisting cardiovascular risk factors in addition to hypoglycemia may be the major link to the final cardiovascular event, but a low blood glucose level can trigger these events in patients with a high cardiovascular risk.

Diabetes for Cardiologists: Practical Issues in Diagnosis and Management

Diabetes mellitus (DM), a chronic metabolic disease characterized by hyperglycemia, is a profound cardiovascular (CV) risk factor. It compounds the effects of all other risk factors, leads to premature micro- and macrovascular disease, facilitates development of heart failure, worsens the clinical course of all CV diseases, and shortens life expectancy. Established DM, unrecognized DM, and dysglycemia that may progress to DM are all commonly present at the time of presentation of overt CV disease. Thus, CV specialists and trainees frequently treat patients with dysglycemia. The traditional and proven role of cardiologists in reducing the risk of macrovascular events in this population is through aggressive lipid and blood pressure treatment. However, a more proactive role in the detection and management of DM is likely to become increasingly important as the prevalence continues to increase and therapies continue to improve. The latter include antihyperglycemic therapies with proven cardiovascular safety profiles and CV event reduction properties not yet fully elucidated and not necessarily related to glycemic control. Accordingly, the purpose of this article is to (1) expand the interest of cardiologists in earlier stages of the natural history of DM, when prevention or early detection might help achieve greatest benefit; (2) highlight principles of optimal glycemic management, with an emphasis on add-on choices showing promising reduction of CV events and lacking CV adverse effects; and (3) encourage cardiologists to become proactive partners in the multidisciplinary care needed to ensure optimal lifelong vascular health in patients with, or who are at risk of, DM.

Assessment of arterial stiffness in type 1 diabetes using digital pulse contour analysis: Is it a reliable method?

AIMS

The aim of this study was to assess the arterial stiffness in patients with type 1 diabetes compared with a control group and determine the associated potential risk factors for its occurrence.

METHODS

Fifty-seven subjects with type 1 diabetes and fifty-three healthy controls were submitted to clinical and laboratory evaluation. The peripheral waveform pressure was analyzed to assess arterial stiffness according to the reflection and stiffness index.

RESULTS

Arterial stiffness did not differ between the controls and patients with type 1 diabetes. Pulse pressure showed no difference among both groups. In the group of patients with type 1 diabetes, the stiffness index was correlated with diabetes duration (r = 0.59, p < 0.001), body mass index (r = 0.27, p = 0.03), diastolic blood pressure (r = 0.33, p = 0.001), triglycerides (r = 0.35, p = 0.007), and age (r = 0.46, p < 0.001). The reflection index was correlated with the systolic blood pressure (r = 0.29, p = 0.02), diastolic blood pressure (r = 0.30, p = 0.02), and cardiac frequency (r = 0.48, p < 0.001). In the stepwise multivariate analysis, disease duration, diastolic blood pressure, and HDL cholesterol were the most important independent variables associated with arterial stiffness in patients with type 1 diabetes.

CONCLUSIONS

We concluded that in the studied population, arterial stiffness showed no difference between patients with diabetes and controls; thus, the use of this method should not be indicated for routine clinical practice in type 1 diabetes.

Hypoglycemia and Cardiovascular Disease: Lessons from Outcome Studies

Severe hypoglycemia is recognized to be one of the strongest predictors of macrovascular events, adverse clinical outcomes, and mortality in patients with type 2 diabetes. Large clinical trials have reported an increased hazard ratio for all-cause mortality and cardiovascular events in patients with type 2 diabetes and severe hypoglycemia. However, these trials also reported an increased hypoglycemia-associated mortality rate in patients allocated to standard treatment by a factor of 1.5-2 despite a significant 50 % to 70 % lower incidence of hypoglycemia compared to the intensive treatment group. Although the potential for a causal relationship has been demonstrated in mechanistic studies, the evidence from large prospective studies suggest that other pre-existing cardiovascular risk factors in addition to hypoglycemia may be the major link to the final cardiovascular event, and that a low blood glucose level can trigger these events in patients with a high cardiovascular risk.

Update on strategies limiting iatrogenic hypoglycemia

The prevalence of type 2 diabetes mellitus (T2DM) is increasing all over the world. Targeting good glycemic control is fundamental to avoid the complications of diabetes linked to hyperglycemia. This narrative review is based on material searched for and obtained via PubMed up to April 2015. The search terms we used were: 'hypoglycemia, diabetes, complications' in combination with 'iatrogenic, treatment, symptoms.' Serious complications might occur from an inappropriate treatment of hyperglycemia. The most frequent complication is iatrogenic hypoglycemia that is often associated with autonomic and neuroglycopenic symptoms. Furthermore, hypoglycemia causes acute cardiovascular effects, which may explain some of the typical symptoms: ischemia, QT prolongation, and arrhythmia. With regards to the latter, the night represents a dangerous period because of the major increase in arrhythmias and the prolonged period of hypoglycemia; indeed, sleep has been shown to blunt the sympatho-adrenal response to hypoglycemia. Two main strategies have been implemented to reduce these effects: monitoring blood glucose values and individualized HbA1c goals. Several drugs for the treatment of T2DM are currently available and different combinations have been recommended to achieve individualized glycemic targets, considering age, comorbidities, disease duration, and life expectancy. In conclusion, according to international guidelines, hypoglycemia-avoiding therapy must reach an individualized glycemic goal, which is the lowest HbA1c not causing severe hypoglycemia and preserving awareness of hypoglycemia.

Hypoglycemia and risk of cardiovascular disease and all-cause mortality in insulin-treated people with type 1 and type 2 diabetes: a cohort study

OBJECTIVE

Hypoglycemia has been associated with an increased risk of cardiovascular (CV) events and all-cause mortality. This study assessed whether, in a nationally representative population, there is an association between hypoglycemia, the risk of CV events, and all-cause mortality among insulin-treated people with type 1 diabetes or type 2 diabetes.

RESEARCH DESIGN AND METHODS

This retrospective cohort study used data from the Clinical Practice Research Datalink database and included all insulin-treated patients (≥30 years of age) with a diagnosis of diabetes.

RESULTS

In patients who experienced hypoglycemia, hazard ratios (HRs) for CV events in people with type 1 diabetes were 1.51 (95% CI 0.83, 2.75; P = ns) and 1.61 (1.17, 2.22), respectively, for those with and without a history of CV disease (CVD) before the index date. In people with type 2 diabetes, the HRs for patients with and without a history of CVD were 1.60 (1.21, 2.12) and 1.49 (1.23, 1.82), respectively. For all-cause mortality, HRs in people with type 1 diabetes were 1.98 (1.25, 3.17), and 2.03 (1.66, 2.47), respectively, for those with and without a history of CVD. Among people with type 2 diabetes, HRs were 1.74 (1.39, 2.18) and 2.48 (2.21, 2.79), respectively, for those with and without a history of CVD. The median time (interquartile range) from first hypoglycemia event to first CV event was 1.5 years (0.5, 3.5 years) and 1.5 years (0.5, 3.0 years), respectively, for people with type 1 and type 2 diabetes.

CONCLUSIONS

Hypoglycemia is associated with an increased risk of CV events and all-cause mortality in insulin-treated patients with diabetes. The relationship between hypoglycemia and CV outcomes and mortality exists over a long period.

Hypoglycaemia in diabetes mellitus: epidemiology and clinical implications

Hypoglycaemia is a frequent adverse effect of treatment of diabetes mellitus with insulin and sulphonylureas. Fear of hypoglycaemia alters self-management of diabetes mellitus and prevents optimal glycaemic control. Mild (self-treated) and severe (requiring help) hypoglycaemia episodes are more common in type 1 diabetes mellitus but people with insulin-treated type 2 diabetes mellitus are also exposed to frequent hypoglycaemic events, many of which occur during sleep. Hypoglycaemia can disrupt many everyday activities such as driving, work performance and leisure pursuits. In addition to accidents and physical injury, the morbidity of hypoglycaemia involves the cardiovascular and central nervous systems. Whereas coma and seizures are well-recognized neurological sequelae of hypoglycaemia, much interest is currently focused on the potential for hypoglycaemia to cause dangerous and life-threatening cardiac complications, such as arrhythmias and myocardial ischaemia, and whether recurrent severe hypoglycaemia can cause permanent cognitive impairment or promote cognitive decline and accelerate the onset of dementia in middle-aged and elderly people with diabetes mellitus. Prevention of hypoglycaemia is an important part of diabetes mellitus management and strategies include patient education, glucose monitoring, appropriate adjustment of diet and medications in relation to everyday circumstances including physical exercise, and the application of new technologies such as real-time continuous glucose monitoring, modified insulin pumps and the artificial pancreas.

Hypoglycemia from a cardiologist's perspective

Hypoglycemia in people with diabetes mellitus (DM) has been potentially linked to cardiovascular morbidity and mortality. Pathophysiologically, hypoglycemia triggers activation of the sympathoadrenal system, leading to an increase in counter-regulatory hormones and, consequently, increased myocardial workload and oxygen demand. Additionally, hypoglycemia triggers proinflammatory and hematologic changes that provide the substrate for possible myocardial ischemia in the already-diseased diabetic cardiovascular system. Hypoglycemia creates electrophysiologic alterations causing P-R-interval shortening, ST-segment depression, T-wave flattening, reduction of T-wave area, and QTc-interval prolongation. Patients who experience hypoglycemia are at an increased risk of silent ischemia as well as QTc prolongation and consequent arrhythmias. The Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial showed an increase in all-cause mortality with intensive glycemic control, whereas the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) study and Veteran's Affairs Diabetes Trial (VADT) showed no benefit with aggressive glycemic control. Women, elderly patients, and those with renal insufficiency are more vulnerable to hypoglycemic events. In fact, hypoglycemia is the most common metabolic complication experienced by older patients with DM in the United States. The concurrent use of medications like β-blockers warrants caution in DM because they can mask warning signs of hypoglycemia. Here we aim to elucidate the pathophysiology, review the electrocardiographic changes, analyze the current clinical literature, and consider the safety considerations of hypoglycemia as it relates to the cardiovascular system. In conclusion, in the current era of DM and its vascular ramifications, hypoglycemia from a cardiologist's perspective deserves due attention.

Type 1 diabetes and cardiovascular disease

The presence of cardiovascular disease (CVD) in Type 1 diabetes largely impairs life expectancy. Hyperglycemia leading to an increase in oxidative stress is considered to be the key pathophysiological factor of both micro- and macrovascular complications. In Type 1 diabetes, the presence of coronary calcifications is also related to coronary artery disease. Cardiac autonomic neuropathy, which significantly impairs myocardial function and blood flow, also enhances cardiac abnormalities. Also hypoglycemic episodes are considered to adversely influence cardiac performance. Intensive insulin therapy has been demonstrated to reduce the occurrence and progression of both micro- and macrovascular complications. This has been evidenced by the Diabetes Control and Complications Trial (DCCT) / Epidemiology of Diabetes Interventions and Complications (EDIC) study. The concept of a metabolic memory emerged based on the results of the study, which established that intensified insulin therapy is the standard of treatment of Type 1 diabetes. Future therapies may also include glucagon-like peptide (GLP)-based treatment therapies. Pilot studies with GLP-1-analogues have been shown to reduce insulin requirements.

Hypoglycemia: The neglected complication

Hypoglycemia is an important complication of glucose-lowering therapy in patients with diabetes mellitus. Attempts made at intensive glycemic control invariably increases the risk of hypoglycemia. A six-fold increase in deaths due to diabetes has been attributed to patients experiencing severe hypoglycemia in comparison to those not experiencing severe hypoglycemia Repeated episodes of hypoglycemia can lead to impairment of the counter-regulatory system with the potential for development of hypoglycemia unawareness. The short- and long-term complications of diabetes related hypoglycemia include precipitation of acute cerebrovascular disease, myocardial infarction, neurocognitive dysfunction, retinal cell death and loss of vision in addition to health-related quality of life issues pertaining to sleep, driving, employment, recreational activities involving exercise and travel. There is an urgent need to examine the clinical spectrum and burden of hypoglycemia so that adequate control measures can be implemented against this neglected life-threatening complication. Early recognition of hypoglycemia risk factors, self-monitoring of blood glucose, selection of appropriate treatment regimens with minimal or no risk of hypoglycemia and appropriate educational programs for healthcare professionals and patients with diabetes are the major ways forward to maintain good glycemic control, minimize the risk of hypoglycemia and thereby prevent long-term complications.

Intensive glucose control and hypoglycaemia: a new cardiovascular risk factor?

Intensive glucose control is widely practiced in patients with diabetes mellitus and patients acutely admitted to hospitals with concomitant stress-induced hyperglycaemia. Such a strategy increases the risk of hypoglycaemia by several-fold. Hypoglycaemia leads to a surge in catecholamine levels with a profound haemodynamic response. In patients with a decreased cardiac reserve, such significant changes can culminate in serious or even fatal cardiovascular outcomes. This review is aimed at discussing in depth the evidence to date that links hypoglycaemia with cardiovascular mortality, reviewing the likely mechanisms underlying this association, as well as summarising these from a cardiologist's perspective.

Cardiovascular disease and glycemic control in type 2 diabetes: now that the dust is settling from large clinical trials

The relationship between glucose control and cardiovascular outcomes in type 2 diabetes has been a matter of controversy over the years. Although epidemiological evidence exists in favor of an adverse role of poor glucose control on cardiovascular events, intervention trials have been less conclusive. The Action to Control Cardiovascular Risk in Diabetes (ACCORD) study, the Action in Diabetes and Vascular Disease (ADVANCE) study, and the Veterans Affairs Diabetes Trial (VADT) have shown no beneficial effect of intensive glucose control on primary cardiovascular endpoints in type 2 diabetes. However, subgroup analysis has provided evidence suggesting that the potential beneficial effect largely depends on patients’ characteristics, including age, diabetes duration, previous glucose control, presence of cardiovascular disease, and risk of hypoglycemia. The benefit of strict glucose control on cardiovascular outcomes and mortality may be indeed hampered by the extent and frequency of hypoglycemic events and could be enhanced if glucose-lowering medications, capable of exerting favorable effects on the cardiovascular system, were used. This review examines the relationship between intensive glucose control and cardiovascular outcomes in type 2 diabetes, addressing the need for individualization of glucose targets and careful consideration of the benefit/risk profile of antidiabetes medications.

Hypoglycaemic episodes and risk of dementia in diabetes mellitus: 7-year follow-up study

OBJECTIVE

We investigated the risk of dementia in patients with type 2 diabetes with or without prior hypoglycaemic episodes.

SUBJECTS AND SETTING

One million subjects randomly selected from the National Health Insurance Research Database, Taiwan.

RESULTS

A total of 15 404 diabetic subjects without prior dementia and a mean age of 64.2 years were enrolled in the study. About 2% (n = 289) of participants had at least one episode of hypoglycaemia in a 3-year period; these subjects were older and more likely to be women and also had higher rates of insulin use and comorbidities compared to those without hypoglycaemia. During a total of 7 years of follow-up (mean and median follow-up, 3.8 and 4.8 years, respectively), 1106 patients with diabetes (7.2%) developed dementia. The incidence rate of dementia was higher in diabetic subjects with [29.9 per 1000 person-years (95% CI 22.1-39.2)] compared to those without [11.1 per 1000 person-years (95% CI 10.3-11.8)] hypoglycaemic episodes. The crude rate ratio (RR) and age- and gender-adjusted RR values for dementia were 2.76 (95% CI 2.06-3.70, P < 0.001) and 1.60 (95% CI 1.19-2.14, P = 0.002), respectively, in diabetic subjects with hypoglycaemia compared to those without hypoglycaemia. Results of Cox proportional hazards analysis revealed that hypoglycaemia, older age, female gender and insulin use were independent predictors of dementia.

CONCLUSION

Adult diabetic patients with prior hypoglycaemia had a significantly increased risk of dementia. The influence of hypoglycaemic episodes on brain function warrants further investigation.

Hypoglycemia, but not glucose variability, relates to vascular function in children with type 1 diabetes

BACKGROUND

Chronic sustained hyperglycemia unequivocally predicts vascular disease in diabetes. However, the vascular risk of glucose variability, including hypoglycemia, is uncertain. Vascular dysfunction is present in children with type 1 diabetes and is a critical precursor of atherosclerosis. We aimed to evaluate the relationship between glucose variability and vascular function in children with type 1 diabetes.

SUBJECTS AND METHODS

Fifty-two type 1 diabetes subjects (14 [SD 2.7] years old, 25 males) had continuous glucose monitoring that included 48 h of data used to evaluate glucose variability (mean amplitude of glycemic excursions [MAGE] and other measurements) and hypoglycemia indices (glycemic risk assessment diabetes equation [GRADE] hypoglycemia, Low Blood Glucose Index [LBGI], and observed duration of hypoglycemia). Children with type 1 diabetes and 50 age- and gender-matched controls had assessments of vascular function (flow-mediated dilatation [FMD] and glyceryl trinitrate-mediated dilatation [GTN]).

RESULTS

Children with type 1 diabetes had lower FMD and GTN than controls (P=0.02 and P<0.001, respectively). GRADE hypoglycemia and LBGI were inversely related to FMD (r=-0.36, P=0.009 and r=-0.302, P=0.03, respectively) but did not relate to GTN. GRADE hypoglycemia was independently related to FMD (regression coefficient=-0.25±0.09, P=0.006). MAGE and other measurements of glucose variability measurements did not relate to FMD or GTN.

CONCLUSIONS

Hypoglycemia, but not glucose variability, during continuous glucose monitoring relates to impaired vascular endothelial function in children with type 1 diabetes. Hypoglycemia may be an additional risk factor for early cardiovascular disease, but the effect of glucose variability, independent of glycosylated hemoglobin, on vascular function remains uncertain.

Does hypoglycemia cause cardiovascular events?

Hypoglycemia is a very common side effect of insulin therapy and, to a lesser extent, of treatment with oral hypoglycemic agents. Severe hypoglycemia can precipitate adverse cardiovascular outcomes such as myocardial ischemia and cardiac arrhythmia. These are mainly secondary to autonomic activation which results in hemodynamic changes, vasoconstriction and rise in intravascular coagulability and viscosity.

Changes in pulse pressure, heart rate and the pulse pressure x heart rate product during squatting in Type 1 diabetes according to age

AIMS

We assessed changes in pulse pressure and heart rate during a squatting test, as indirect markers of arterial stiffness and cardiovascular autonomic neuropathy, respectively, according to age and sex in patients with Type 1 diabetes mellitus.

METHODS

We evaluated 160 diabetic patients, divided into four groups of 20 men and 20 women according to age (G1, 20-30 years old; G2, 31-40 years old; G3, 41-50 years old; and G4, 51-60 years old), and 160 non-diabetic matched control subjects. Each subject underwent a 3 min posture test (standing-squatting-standing) with continuous measurement of arterial blood pressure and heart rate by a Finapres device. Overall values throughout the test, baseline levels in initial standing position and squatting-induced changes in pulse pressure, heart rate and the pulse pressure x heart rate product were compared between diabetic patients and healthy control subjects.

RESULTS

In the standing position, a greater increase in pulse pressure and lower reduction in heart rate with age led to a significantly higher pulse pressure x heart rate product in diabetic patients compared with control subjects. In the squatting position, a more marked pulse pressure increase in the absence of appropriate reduction in heart rate resulted in a greater rise in the pulse pressure x heart rate product in diabetic patients than in healthy subjects. No major differences were noted between the sexes, with the exception of a stronger relationship between pulse pressure and age in the female population with diabetes. Squatting-derived indices of cardiovascular autonomic neuropathy were also noted with increasing age in diabetic patients.

CONCLUSIONS

The marked increase in the pulse pressure x heart rate product ('pulsatile stress') according to age, combined with cardiovascular autonomic neuropathy, may contribute to the higher cardiovascular risk of patients with Type 1 diabetes.

Noninvasive measurement of central vascular pressures with arterial tonometry: clinical revival of the pulse pressure waveform?

The arterial pulse has historically been an essential source of information in the clinical assessment of health. With current sphygmomanometric and oscillometric devices, only the peak and trough of the peripheral arterial pulse waveform are clinically used. Several limitations exist with peripheral blood pressure. First, central aortic pressure is a better predictor of cardiovascular outcome than peripheral pressure. Second, peripherally obtained blood pressure does not accurately reflect central pressure because of pressure amplification. Lastly, antihypertensive medications have differing effects on central pressures despite similar reductions in brachial blood pressure. Applanation tonometry can overcome the limitations of peripheral pressure by determining the shape of the aortic waveform from the radial artery. Waveform analysis not only indicates central systolic and diastolic pressure but also determines the influence of pulse wave reflection on the central pressure waveform. It can serve as a useful adjunct to brachial blood pressure measurements in initiating and monitoring hypertensive treatment, in observing the hemodynamic effects of atherosclerotic risk factors, and in predicting cardiovascular outcomes and events. Radial artery applanation tonometry is a noninvasive, reproducible, and affordable technology that can be used in conjunction with peripherally obtained blood pressure to guide patient management. Keywords for the PubMed search were applanation tonometry, radial artery, central pressure, cardiovascular risk, blood pressure, and arterial pulse. Articles published from January 1, 1995, to July 1, 2009, were included in the review if they measured central pressure using radial artery applanation tonometry.

Review: Does hypoglycaemia cause cardiovascular events?

Strict glycaemic control is strongly advocated in people with type 2 diabetes to prevent vascular disease. However, the outcomes of two large clinical trials have indicated the potential dangers of pursuing this policy in those at high risk of cardiovascular disease, with an excess of fatal vascular events being associated with a higher frequency of severe hypoglycaemia. Hypoglycaemia secondary to insulin and sulphonylurea therapy is often associated with serious morbidity; anecdotal evidence has long implicated hypoglycaemia as a potential cause of myocardial ischaemia or a cardiac arrhythmia. Hypoglycaemia provokes sympatho-adrenal activation and counterregulatory hormone secretion, which exert pronounced cardiovascular effects. Although well tolerated in healthy people, the superimposition of these profound physiological effects on a diseased coronary vasculature and a dysfunctional cardiac conductive system may induce serious or even fatal cardiovascular events. These risks should influence therapeutic targets and the approach to diabetes management in people with diabetes with established vascular disease in whom exposure to severe hypoglycaemia could be dangerous.

Free fatty acids are associated with pulse pressure in women, but not men, with type 1 diabetes mellitus

Cardiovascular disease (CVD) is the leading cause of death in type 1 diabetes mellitus (T1D). Pulse pressure, a measure of arterial stiffness, is elevated in T1D and associated with CVD. Free fatty acids (FFAs), elevated in women and abdominal adiposity, are also elevated in T1D and CVD. We thus examined the association of fasting FFAs with pulse pressure and coronary artery calcification (CAC, a marker of coronary atherosclerotic burden) in an adult population (n = 150) of childhood-onset T1D and whether any such associations varied by abdominal adiposity and sex. Mean age and diabetes duration were 42 and 33 years, respectively, when CAC, visceral abdominal adiposity (VAT), and subcutaneous abdominal adiposity (SAT) were determined by electron beam tomography. Free fatty acids were determined by in vitro colorimetry. Pulse pressure was calculated as systolic blood pressure minus diastolic blood pressure. Free fatty acids were log transformed before analyses, and all analyses were controlled for serum albumin. Free fatty acids were associated with pulse pressure in women (r = 0.24, P = .04), but not in men (r = 0.07, P = .55). An interaction for the prediction of pulse pressure was noted between FFAs and both VAT (P = .03) and SAT (P = .008) in women, but only a marginal interaction with SAT (P = .09) and no interaction for VAT (P = .40) with FFAs were observed in men. In multivariable linear regression analysis allowing for serum albumin, age, height, heart rate, albumin excretion rate, hemoglobin A(1c), high-density lipoprotein cholesterol, hypertension medication use, FFAs, SAT, and the interaction between FFAs and SAT, the interaction between FFAs and SAT remained associated with pulse pressure in women (FFAs, P = .04; interaction term, P = .03), but not men (FFAs, P = .32; interaction term, P = .32). FFAs showed no association with log-transformed CAC. Although FFAs were not associated with CAC in either sex, they were associated with pulse pressure in women and their effect appeared to vary by abdominal adiposity, particularly SAT. This finding might help explain the loss of the sex difference in CVD in T1D.

Pulse pressure and cardiovascular autonomic neuropathy according to duration of type 1 diabetes

BACKGROUND

To evaluate changes in pulse pressure (PP) and markers of cardiovascular autonomic neuropathy (CAN) according to duration of type 1 diabetes mellitus (T1DM).

METHODS

This cross-sectional controlled study evaluated 159 diabetic patients during a 3-min posture test (standing-squatting-standing) with continuous measurement of systolic (SBP), diastolic (DBP) and mean (MBP) blood pressure by a Finapres device. Arterial stiffness was indirectly assessed by PP and the slope of PP as a function of MBP calculated during the whole 3-min test. CAN was assessed by the expiration/inspiration pulse interval ratio (E/I R-R ratio) during deep breathing and by three indices measured during the squatting test. Patients were divided into four groups according to diabetes duration (<10 years, 11-20 years, 21-30 years and > 30 years from group 1 to group 4, respectively) and compared with age-matched non-diabetic subjects.

RESULTS

PP progressively increased (p < 0.0001) and PP/MBP decreased (p < 0.0005) according to T1DM duration, whereas these parameters remained almost unchanged in age-matched control subjects. E/I ratio (p < 0.0001) and baroreflex gain (p < 0.0005) progressively decreased with T1DM duration. The parasympathetic index (squatting test vagal ratio-SqTv) significantly increased (p < 0.0001), whereas the sympathetic index (squatting test sympathetic ratio-SqTs) only tended to decrease (p = 0.12) according to diabetes duration. No such changes in CAN indices were observed in the non-diabetic population.

CONCLUSIONS

PP increased according to T1DM duration in an age range where PP remained almost stable in controls, in agreement with accelerated arterial stiffening due to chronic hyperglycaemia. The baroreflex gain decreased and other indices of CAN also deteriorated with diabetes duration, more so indices reflecting parasympathetic rather than sympathetic dysfunction.

Arterial stiffness, carotid artery intima-media thickness and plasma myeloperoxidase level in children with type 1 diabetes

OBJECTIVE

The present study investigated the functional-structural changes of the arteries along with a new biochemical marker of atherosclerosis, plasma myeloperoxidase level, in children with type 1 diabetes (T1DM).

METHODS

We studied 30 children with T1DM, aged 4.7-18.6 years (mean T1DM duration 5.4+/-3.4 years, mean HbA(1c) 9.8%) and 30 healthy subjects, matched by sex, age and body mass index. Fasting blood samples were obtained for myeloperoxidase (MPO). Ultrasonography and pulse wave analysis were used to measure carotid intima-media thickness (IMT), augmentation index corrected to a heart rate of 75 (AIx@75) and pulse wave velocity (PWV).

RESULTS

Children with diabetes had significantly higher plasma MPO levels (p=0.006), increased AIx@75 (p=0.02), IMT (p=0.005) and IMT standard deviation scores (IMT SDS) (p=0.02), compared to the control group. IMT SDS correlated positively with HbA(1c) (r=0.39, p=0.05). PWV, adjusted for age and mean arterial blood pressure, correlated with diabetes duration (r=0.49, p=0.02).

CONCLUSIONS

Children with T1DM have substantially elevated plasma levels of myeloperoxidase as well as atherosclerosis-related structural and functional changes of the arterial wall.

Effects of experimentally induced diabetes mellitus on pharmacologically and electrically elicited myometrial contractility

1. Diabetes is one of the most frequent complications of gestation, affecting approximately 7% of pregnancies. However, little is known about its effects on electrically and pharmacologically stimulated myometrial contractility. The aim of the present study was to investigate the consequences of streptozotocin (STZ)-induced diabetes on: (i) electrical field stimulation (EFS)-evoked contraction of isolated uterine rings as a function of gestational age; and (ii) the uterotonic and tocolytic actions of α- and β-adrenoceptor stimulation, respectively. The effects of oxytocin in late pregnancy were also investigated. 2. During pregnancy, EFS-evoked contractions of isolated uterine rings from intact rats declined, whereas isolated uterine rings from diabetic rats exhibited continuously low sensitivity to EFS. 3. In non-pregnant rats, diabetes resulted in increased noradrenaline-mediated contractility and a decreased relaxation response to terbutaline. At the mRNA level, diabetes enhanced the expression of α1B-adrenoceptors in non-pregnant rats from 14.65 to 18.39 μg/mL (P < 0.05), whereas the expression of α1D-adrenoceptors decreased (from 42.87 to 35.67 μg/mL; P < 0.05). During pregnancy, the responses to these sympathomimetics did not differ between diabetic and intact rats. 4. In late pregnancy (on Days 15 and 21), oxytocin caused greater maximum contractility of uterine rings from diabetic rats without affecting the EC(50). In addition, on Day 15 of pregnancy, the expression of oxytocin receptors in the myometrium of diabetic rats was higher than that in intact rats. 5. The results of the present study indicate that experimental diabetes facilitates gestation-induced denervation and increases myometrial sensitivity to oxytocin in late pregnancy. If similar mechanisms operate in humans, this could contribute to a tendency to premature uterine contractions in diabetes-complicated pregnancies.

Exercise training impacts the myocardial metabolism of older individuals in a gender-specific manner

Aging is associated with decreases in aerobic capacity, cardiac function, and insulin sensitivity as well as alterations in myocardial substrate metabolism. Endurance exercise training (EET) improves cardiac function in a gender-specific manner, and EET has been shown to improve whole body glucose tolerance, but its effects on myocardial metabolism are unclear. Accordingly, we studied the effect of EET on myocardial substrate metabolism in older men and women. Twelve healthy older individuals (age: 60-75 yr; 6 men and 6 women) underwent PET with [(15)O]water, [(11)C]acetate, [(11)C]glucose, and [(11)C]palmitate for the assessment of myocardial blood flow (MBF), myocardial O(2) consumption (MVo(2)), myocardial glucose utilization (MGU), and myocardial fatty acid utilization (MFAU), respectively, at rest and during dobutamine infusion (10 microg.kg(-1).min(-1)). Measurements were repeated after 11 mo of EET. Maximal O(2) uptake (Vo(2max)) increased (P = 0.005) after EET. MBF was unaffected by training, as was resting MVo(2); however, posttraining dobutamine MVo(2) was significantly higher (P = 0.05), as was MGU (P < 0.04). Although overall dobutamine MFAU was unchanged, posttraining dobutamine MFAU increased in women (P = 0.01) but decreased in men (P = 0.03). Thus, EET in older individuals improves the catecholamine response of myocardial glucose metabolism. Moreover, gender differences exist in the myocardial fatty acid metabolic response to training. These findings suggest a role for altered myocardial substrate metabolism in modulating the cardiovascular benefits of EET in older individuals.