When are type 1 diabetic patients at risk for cardiovascular disease?

Long term risk of heart failure in individuals with childhood-onset type 1 diabetes

BACKGROUND

We aimed to evaluate the risk of heart failure in young adults with childhood-onset type 1 diabetes from the Pittsburgh Epidemiology of Diabetes Complications (EDC) Study. We also examined risk factors and microvascular disease burden associated with the incidence of heart failure.

METHODS

Participants in the EDC study without known baseline heart failure (n = 655) were enrolled and then followed for 25 years. "Any" heart failure comprised the underlying cause of death, primary reason for hospitalization, EDC clinic examination findings or self-report of a physician diagnosis. "Hard" heart failure was determined only by the underlying cause of death or primary reason for hospitalization. Incidence rates for heart failure were estimated using Poisson models. Cox models were constructed to examine the associations between risk factors and microvascular disease burden with incident heart failure.

RESULTS

The mean baseline age and diabetes duration were 27(8) years and 19 (8) years. Incidence for any and hard heart failure were 3.4 and 1.8/1000 person-years. Diabetes duration, ever smoking and triglycerides were significant risk factors of any heart failure; longer diabetes duration, lower estimated glomerular filtration rate and higher white blood cell count significantly predicted hard heart failure. A gradient association was observed between the number of microvascular disease (from 0 to 3) and "hard" heart failure endpoint but not "any" clinically defined heart failure.

CONCLUSION

Young adults with long-duration type 1 diabetes had a high risk of heart failure. As microvascular disease burden increases so does the risk of heart failure independently of diabetes duration, A1c and coronary artery disease.

CARDEA study protocol: investigating early markers of cardiovascular disease and their association with lifestyle habits, inflammation and oxidative stress in adolescence using a cross-sectional comparison of adolescents with type 1 diabetes and healthy controls

INTRODUCTION

Little is known regarding associations between potentially modifiable lifestyle habits and early markers of cardiovascular disease (CVD) in pediatric type 1 diabetes (T1D), hindering early prevention efforts. Specific objectives are: (1) compare established risk factors (dyslipidemia, hypertension) with novel early markers for CVD (cardiac phenotype, aortic distensibility, endothelial function) in adolescents with T1D and healthy age-matched and sex-matched controls; (2) examine associations between these novel early markers with: (i) lifestyle habits; (ii) adipokines and measures of inflammation; and (iii) markers of oxidative stress among adolescents with T1D and controls, and determine group differences in these associations; (3) explore, across both groups, associations between CVD markers and residential neighbourhood features.

METHODS AND ANALYSES

Using a cross-sectional design, we will compare 100 participants aged 14-18 years with T1D to 100 healthy controls. Measures include: anthropometrics; stage of sexual maturity (Tanner stages); physical activity (7-day accelerometry); sleep and sedentary behaviour (self-report and accelerometry); fitness (peak oxygen consumption); and dietary intake (three non-consecutive 24- hour dietary recalls). Repeated measures of blood pressure will be obtained. Lipid profiles will be determined after a 12- hour fast. Cardiac structure/function: non-contrast cardiac magnetic resonance imaging (CMR) images will evaluate volume, mass, systolic and diastolic function and myocardial fibrosis. Aortic distensibility will be determined by pulse wave velocity with elasticity and resistance studies at the central aorta. Endothelial function will be determined by flow-mediated dilation. Inflammatory markers include plasma leptin, adiponectin, tumour necrosis factor alpha (TNF-α), type I and type II TNF-α soluble receptors and interleukin-6 concentrations. Measures of endogenous antioxidants include manganese superoxide dismutase, glutathione peroxidase and glutathione in blood. Neighbourhood features include built and social environment indicators and air quality.

ETHICS AND DISSEMINATION

This study was approved by the Sainte-Justine Hospital Research Ethics Board. Written informed assent and consent will be obtained from participants and their parents.

TRIAL REGISTRATION NUMBER

NCT04304729.

Naringenin alleviates myocardial ischemia reperfusion injury by enhancing the myocardial miR-126-PI3K/AKT axis in streptozotocin-induced diabetic rats

Ischemic heart disease (IHD) is a leading cause of death in patients with type 1 diabetes. The key to treating IHD is to restore blood supply to the ischemic myocardium, which inevitably causes myocardial ischemia reperfusion (MI/R) injury. Although naringenin (Nar) prevents MI/R injury, the role of Nar in diabetic MI/R (D-MI/R) injury remains to be elucidated. The PI3K/AKT signaling pathway and microRNA (miR)-126 have previously been shown to serve anti-MI/R injury roles. The present study aimed to investigate the protection of Nar against D-MI/R injury and the role of the miR-126-PI3K/AKT axis. Diabetic rats were treated distilled water or Nar (25 or 50 mg/kg, orally) for 30 days and then exposed to MI/R. The present results revealed that Nar alleviated MI/R injury in streptozotocin (STZ)-induced diabetic rats, as shown below: the reduction myocardial enzymes levels was measured using spectrophotometry, the increase of cardiac viability was detected by MTT assay, the inhibition of myocardial oxidative stress was measured using spectrophotometry and the enhancement of cardiac function were recorded using a hemodynamic monitoring system. Furthermore, Nar upregulated the myocardial miR-126-PI3K/AKT axis in D-MI/R rats. These results indicated that Nar alleviated MI/R injury through upregulating the myocardial miR-126-PI3K/AKT axis in STZ-induced diabetic rats. The current findings revealed that Nar, as an effective agent against D-MI/R injury, may provide an effective approach in the management of diabetic IHD.

Diabetes Impairs Cellular Cholesterol Efflux From ABCA1 to Small HDL Particles

RATIONALE

HDL (high-density lipoprotein) may be cardioprotective because it accepts cholesterol from macrophages via the cholesterol transport proteins ABCA1 (ATP-binding cassette transporter A1) and ABCG1 (ATP-binding cassette transporter G1). The ABCA1-specific cellular cholesterol efflux capacity (ABCA1 CEC) of HDL strongly and negatively associates with cardiovascular disease risk, but how diabetes mellitus impacts that step is unclear.

OBJECTIVE

To test the hypothesis that HDL's cholesterol efflux capacity is impaired in subjects with type 2 diabetes mellitus.

METHODS AND RESULTS

We performed a case-control study with 19 subjects with type 2 diabetes mellitus and 20 control subjects. Three sizes of HDL particles, small HDL, medium HDL, and large HDL, were isolated by high-resolution size exclusion chromatography from study subjects. Then we assessed the ABCA1 CEC of equimolar concentrations of particles. Small HDL accounted for almost all of ABCA1 CEC activity of HDL. ABCA1 CEC-but not ABCG1 CEC-of small HDL was lower in the subjects with type 2 diabetes mellitus than the control subjects. Isotope dilution tandem mass spectrometry demonstrated that the concentration of SERPINA1 (serpin family A member 1) in small HDL was also lower in subjects with diabetes mellitus. Enriching small HDL with SERPINA1 enhanced ABCA1 CEC. Structural analysis of SERPINA1 identified 3 amphipathic α-helices clustered in the N-terminal domain of the protein; biochemical analyses demonstrated that SERPINA1 binds phospholipid vesicles.

CONCLUSIONS

The ABCA1 CEC of small HDL is selectively impaired in type 2 diabetes mellitus, likely because of lower levels of SERPINA1. SERPINA1 contains a cluster of amphipathic α-helices that enable apolipoproteins to bind phospholipid and promote ABCA1 activity. Thus, impaired ABCA1 activity of small HDL particles deficient in SERPINA1 could increase cardiovascular disease risk in subjects with diabetes mellitus.

Risk factors differ by first manifestation of cardiovascular disease in type 1 diabetes

AIMS

We compared risk factors for three CVD manifestations and a composite outcome over 25 years' follow-up in the Pittsburgh Epidemiology of Diabetes Complications (EDC) prospective cohort study of childhood-onset (<17 years) type 1 diabetes (n = 658).

METHODS

First CVD manifestations examined were: (1) major atherosclerotic cardiovascular event (MACE, i.e. CVD death, myocardial infarction, stroke), (2) coronary revascularization, (3) soft coronary artery disease (CAD, i.e. ischemia ECG, angina), and a (4) composite (MACE + revascularization) outcome. Baseline and time-varying mean and current risk factors, including medication use, were assessed, in diabetes duration-adjusted models.

RESULTS

MACE (n = 107) was predicted by ln(albumin excretion rate) (AER, HR = 1.3, p < 0.0001), systolic BP (SBP, HR = 1.03, p < 0.0001), white blood cell count (WBC, HR = 1.2, p < 0.0001), HbA1c (HR = 1.2p = 0.03), LDLc (HR = 1.01, p = 0.03). Soft CAD (n = 91) was predicted by ln(AER) (HR = 1.2, p = 0.004), SBP (HR = 1.03, p = 0.0002), WBC (HR = 1.2, p = 0.0003), HbA1c (HR = 1.2, p = 0.005). Revascularization (n = 38) was predicted by LDLc (HR = 1.03, p < 0.0001), eGFR (HR = 0.98, p = 0.002), HbA1c (HR = 1.3, p = 0.03). Adding revascularization to MACE enhanced the role of LDLc, while diminishing that of HbA1c, compared to MACE alone.

CONCLUSIONS

Important risk factor associations may be affected by examining composite CVD outcomes. More research is needed to determine how to best incorporate revascularization into composite CVD definitions.

Glucose Management and the Sex Difference in Excess Cardiovascular Disease Risk in Long-Duration Type 1 Diabetes

PURPOSE OF REVIEW

The protection against CVD observed in women compared to men in the general population is essentially erased in type 1 diabetes. This review will discuss evidence regarding the role of glucose management on CVD risk by sex, with a particular focus on studies of long-duration type 1 diabetes of > 20 years.

RECENT FINDINGS

Across studies, women with type 1 diabetes have similar or worse glycemic control compared to men, despite higher rates of intensive insulin therapy. The association between HbA1c and CVD risk does not seem to differ by sex, but few studies have reported on sex-specific analyses. Beyond HbA1c, there is a lack of published data regarding the relationship between other aspects of glucose management and CVD risk by sex in type 1 diabetes. Glucose management factors do not seem to directly account for the increased CVD risk in women with type 1 diabetes, but may influence other risk factors that play a more direct role.

Hemoglobin A1c Level and Cardiovascular Disease Incidence in Persons With Type 1 Diabetes: An Application of Joint Modeling of Longitudinal and Time-to-Event Data in the Pittsburgh Epidemiology of Diabetes Complications Study

Type 1 diabetes (T1D) is associated with increased risk of cardiovascular disease (CVD), but hyperglycemia (measured by hemoglobin A1c (HbA1c) level), which characterizes T1D, has itself been an inconsistent predictor of CVD incidence. However, only baseline HbA1c or a summary measure (e.g., mean level over follow-up) is usually analyzed. Joint models allow simultaneous modeling of repeatedly measured longitudinal covariates, using random effects, and time-to-event data. We evaluated data from the Pittsburgh Epidemiology of Diabetes Complications Study, an ongoing prospective cohort study of childhood-onset T1D that has followed participants since 1986-1988 and has repeatedly found little association between baseline HbA1c or mean follow-up HbA1c and coronary artery disease incidence. Of 561 participants without CVD at baseline, 263 (46.9%) developed CVD over a period of 25 years (1986-2014). In joint models, each 1% unit increase in HbA1c trajectory was associated with a 1.26-fold increased risk of CVD (95% confidence interval: 1.07, 1.45), after adjustment for baseline levels of other CVD risk factors, and a 1.13-fold increased risk (95% confidence interval: 0.99, 1.32) after adjustment for updated mean levels of other CVD risk factors. These findings, which support the need for good glycemic control to prevent CVD in persons with T1D, underscore the importance of utilizing methods incorporating within-subject variation over time when analyzing and interpreting longitudinal cohort study data.

Honokiol Ameliorates Myocardial Ischemia/Reperfusion Injury in Type 1 Diabetic Rats by Reducing Oxidative Stress and Apoptosis through Activating the SIRT1-Nrf2 Signaling Pathway

Reducing oxidative stress is a crucial therapeutic strategy for ameliorating diabetic myocardial ischemia/reperfusion (MI/R) injury. Honokiol (HKL) acts as an effective cardioprotective agent for its strong antioxidative activity. However, its roles and underlying mechanisms against MI/R injury in type 1 diabetes (T1D) remain unknown. Since SIRT1 and Nrf2 are pivotal regulators in diabetes mellitus patients suffering from MI/R injury, we hypothesized that HKL ameliorates diabetic MI/R injury via the SIRT1-Nrf2 signaling pathway. Streptozotocin-induced T1D rats and high-glucose-treated H9c2 cells were exposed to HKL, with or without administration of the SIRT1 inhibitor EX527, SIRT1 siRNA, or Nrf2 siRNA, and then subjected to I/R operation. We found that HKL markedly improved the postischemic cardiac function, decreased the infarct size, reduced the myocardial apoptosis, and diminished the reactive oxygen species generation. Intriguingly, HKL remarkably activated SIRT1 signaling, enhanced Nrf2 nuclear translocation, increased antioxidative signaling, and decreased apoptotic signaling. However, these effects were largely abolished by EX527 or SIRT1 siRNA. Additionally, our cellular experiments showed that Nrf2 siRNA blunted the cytoprotective effects of HKL, without affecting SIRT1 expression and activity. Collectively, these novel findings indicate that HKL abates MI/R injury in T1D by ameliorating myocardial oxidative damage and apoptosis via the SIRT1-Nrf2 signaling pathway.

Polydatin Protects Diabetic Heart against Ischemia-Reperfusion Injury via Notch1/Hes1-Mediated Activation of Pten/Akt Signaling

Diabetes exacerbates oxidative/nitrative stress during myocardial ischemia-reperfusion (MI/R) injury. Recent studies highlighted the cardioprotective actions of polydatin. However, its effect on diabetic MI/R injury and the underlying mechanisms remain unknown. This work was undertaken to evaluate the effect of polydatin on diabetic MI/R injury with a focus on Notch1/Hes1 signaling and myocardial oxidative/nitrative stress. Streptozotocin- (STZ-) induced diabetic rats were administered with polydatin (20 mg/kg/d) in the absence or presence of DAPT (a γ-secretase inhibitor) or LY294002 (a PI3K/Akt inhibitor) and then subjected to MI/R injury. Polydatin administration preserved cardiac function and reduced myocardial infarct size. Moreover, polydatin ameliorated myocardial oxidative/nitrative stress damage as evidenced by decreased myocardial superoxide generation, malondialdehyde, gp91^phox expression, iNOS expression, NO metabolite level, and nitrotyrosine content and increased eNOS phosphorylation. However, these effects were blocked by DAPT administration. DAPT also inhibited the stimulatory effect of polydatin on the Notch1/Hes1-Pten/Akt signaling pathway in a diabetic myocardium. Additionally, LY294002 not only abolished polydatin's antiapoptotic effect but also reversed its inhibitory effect on myocardial oxidative/nitrative stress. Polydatin effectively reduced MI/R injury and improved left ventricular functional recovery under diabetic condition by ameliorating oxidative/nitrative stress damage. Importantly, Notch1/Hes1-mediated activation of Pten/Akt signaling played a crucial role in this process.

Cardiovascular complications of type 1 diabetes: update on the renal link

AIMS

Despite recent findings of increased life expectancy among individuals with type 1 diabetes, mortality remains greatly increased compared to the general population. As this is largely the result of cardiovascular and renal complications, we aimed to review recent findings surrounding these diseases in type 1 diabetes.

METHODS

We reviewed published findings concerning the cardiovascular complications of type 1 diabetes, with a particular focus on links with renal disease.

RESULTS

The cardiovascular and renal complications of type 1 diabetes share many features including insulin resistance, oxidative damage, and genetic associations with the Haptoglobin genotype, and both are strongly affected by glycemic control.

CONCLUSIONS

Although current knowledge on predictors of type 1 diabetes cardiovascular and renal complications has increased, further investigation is required to understand the mechanisms leading to cardio-renal complications in this population.

Melatonin ameliorates myocardial ischemia/reperfusion injury in type 1 diabetic rats by preserving mitochondrial function: role of AMPK-PGC-1α-SIRT3 signaling

Enhancing mitochondrial biogenesis and reducing mitochondrial oxidative stress have emerged as crucial therapeutic strategies to ameliorate diabetic myocardial ischemia/reperfusion (MI/R) injury. Melatonin has been reported to be a safe and potent cardioprotective agent. However, its role on mitochondrial biogenesis or reactive oxygen species (ROS) production in type 1 diabetic myocardium and the underlying mechanisms remain unknown. We hypothesize that melatonin ameliorates MI/R injury in type 1 diabetic rats by preserving mitochondrial function via AMPK-PGC-1α-SIRT3 signaling pathway. Both our in vivo and in vitro data showed that melatonin reduced MI/R injury by improving cardiac function, enhancing mitochondrial SOD activity, ATP production and oxidative phosphorylation complex (II, III and IV), reducing myocardial apoptosis and mitochondrial MDA, H₂O₂ generation. Importantly, melatonin also activated AMPK-PGC-1α-SIRT3 signaling and increased SOD2, NRF1 and TFAM expressions. However, these effects were abolished by Compound C (a specific AMPK signaling blocker) administration. Additionally, our cellular experiment showed that SIRT3 siRNA inhibited the cytoprotective effect of melatonin without affecting p-AMPK/AMPK ratio and PGC-1α expression. Taken together, we concluded that melatonin preserves mitochondrial function by reducing mitochondrial oxidative stress and enhancing its biogenesis, thus ameliorating MI/R injury in type 1 diabetic state. AMPK-PGC1α-SIRT3 axis plays an essential role in this process.

Risk stratification for 25-year cardiovascular disease incidence in type 1 diabetes: Tree-structured survival analysis of the Pittsburgh Epidemiology of Diabetes Complications study

BACKGROUND

The formal identification of subgroups with varying levels of risk is uncommon in observational studies of cardiovascular disease, although such insight might be useful for clinical management.

METHODS

Tree-structured survival analysis was utilized to determine whether there are meaningful subgroups at varying levels of cardiovascular disease risk in the Pittsburgh Epidemiology of Diabetes Complications study, a prospective cohort study of childhood-onset (<17 years old) type 1 diabetes.

RESULTS

Of the 561 participants free of cardiovascular disease (coronary artery disease, stroke or lower extremity arterial disease) at baseline, 263 (46.9%) had an incident cardiovascular disease event over the 25-year follow-up. Tree-structured survival analysis revealed a range of risk groups, from 24% to 85%, which demonstrate that those with short diabetes duration and elevated non-high-density lipoprotein cholesterol have similar cardiovascular disease risk to those with long diabetes duration and that renal disease is a better discriminator of risk in men than in women.

CONCLUSION

Our findings suggest that subgroups with major cardiovascular disease risk differences exist in this type 1 diabetes cohort. Using tree-structured survival analysis may help to identify these groups and the interrelationships between their associated risk factors. This approach may improve our understanding of various clinical pathways to cardiovascular disease and help target intervention strategies.

Intensive Diabetes Treatment and Cardiovascular Outcomes in Type 1 Diabetes: The DCCT/EDIC Study 30-Year Follow-up

OBJECTIVE

Early initiation of intensive diabetes therapy aimed at achieving near-normal glycemia reduces the early development of vascular complications in type 1 diabetes. We now assess whether intensive therapy compared with conventional therapy during the Diabetes Control and Complications Trial (DCCT) affected the incidence of cardiovascular disease over 30 years of follow-up.

RESEARCH DESIGN AND METHODS

The DCCT randomly assigned 1,441 patients with type 1 diabetes to intensive versus conventional therapy for a mean of 6.5 years, after which 93% were subsequently monitored during the observational Epidemiology of Diabetes Interventions and Complications (EDIC) study. Cardiovascular disease (nonfatal myocardial infarction and stroke, cardiovascular death, confirmed angina, congestive heart failure, and coronary artery revascularization) was adjudicated using standardized measures.

RESULTS

During 30 years of follow-up in DCCT and EDIC, 149 cardiovascular disease events occurred in 82 former intensive treatment group subjects versus 217 events in 102 former conventional treatment group subjects. Intensive therapy reduced the incidence of any cardiovascular disease by 30% (95% CI 7, 48; P = 0.016), and the incidence of major cardiovascular events (nonfatal myocardial infarction, stroke, or cardiovascular death) by 32% (95% CI -3, 56; P = 0.07). The lower HbA1c levels during the DCCT/EDIC statistically account for all of the observed treatment effect on cardiovascular disease risk. Increased albuminuria was also independently associated with cardiovascular disease risk.

CONCLUSIONS

Intensive diabetes therapy during the DCCT (6.5 years) has long-term beneficial effects on the incidence of cardiovascular disease in type 1 diabetes that persist for up to 30 years.

Update on cardiovascular outcomes at 30 years of the diabetes control and complications trial/epidemiology of diabetes interventions and complications study

OBJECTIVE To describe the beneficial long-term effects of an average of 6.5 years of intensive diabetes therapy (INT) in type 1 diabetes on measures of atherosclerosis, cardiac structure and function, and clinical cardiovascular events observed in the Diabetes Control and Complications Trial (DCCT) and the Epidemiology of Diabetes Interventions and Complications (EDIC) study. RESEARCH DESIGN AND METHODS The DCCT was a randomized clinical trial of 1,441 participants assigned to receive INT or conventional therapy (CON). It was conducted between 1983-1993 with an average follow-up of 6.5 years. EDIC (1994-present) is an observational follow-up of the DCCT cohort. Cardiovascular events have been recorded throughout. During EDIC common carotid intima-media thickness (IMT) was measured with ultrasound, coronary artery calcification with computed tomography, and cardiac structure and function with cardiac magnetic resonance imaging. RESULTS DCCT INT and lower levels of HbA1c during DCCT/EDIC were associated with thinner carotid IMT, less coronary calcification, and a lower incidence of clinical cardiovascular events including myocardial infarction, stroke, and cardiac death. While there were no significant differences in cardiac structure and function between the former INT and CON groups, they were significantly associated with higher HbA1c during DCCT/EDIC. CONCLUSIONS DCCT INT and the attendant 6.5 years of lower HbA1c had long-term salutary effects on the development and progression of atherosclerosis and cardiovascular disease during the subsequent follow-up during EDIC.

De novo lipogenesis and cholesterol synthesis in humans with long-standing type 1 diabetes are comparable to non-diabetic individuals

BACKGROUND

Synthesis of lipid species, including fatty acids (FA) and cholesterol, can contribute to pathological disease. The purpose of this study was to investigate FA and cholesterol synthesis in individuals with type 1 diabetes, a group at elevated risk for vascular disease, using stable isotope analysis.

METHODS

Individuals with type 1 diabetes (n = 9) and age-, sex-, and BMI-matched non-diabetic subjects (n = 9) were recruited. On testing day, meals were provided to standardize food intake and elicit typical feeding responses. Blood samples were analyzed at fasting (0 and 24 h) and postprandial (2, 4, 6, and 8 hours after breakfast) time points. FA was isolated from VLDL to estimate hepatic FA synthesis, whereas free cholesterol (FC) and cholesteryl ester (CE) was isolated from plasma and VLDL to estimate whole-body and hepatic cholesterol synthesis, respectively. Lipid synthesis was measured using deuterium incorporation and isotope ratio mass spectrometry.

RESULTS

Fasting total hepatic lipogenesis (3.91 ± 0.90% vs. 5.30 ± 1.22%; P = 0.41) was not significantly different between diabetic and control groups, respectively, nor was synthesis of myristic (28.60 ± 4.90% vs. 26.66 ± 4.57%; P = 0.76), palmitic (12.52 ± 2.75% vs. 13.71 ± 2.64%; P = 0.65), palmitoleic (3.86 ± 0.91% vs. 4.80 ± 1.22%; P = 0.65), stearic (5.55 ± 1.04% vs. 6.96 ± 0.97%; P = 0.29), and oleic acid (1.45 ± 0.28% vs. 2.10 ± 0.51%; P = 0.21). Postprandial lipogenesis was also not different between groups (P = 0.38). Similarly, fasting synthesis of whole-body FC (8.2 ± 1.3% vs. 7.3 ± 0.8%/day; P = 0.88) and CE (1.9 ± 0.4% vs. 2.0 ± 0.3%/day; P = 0.96) and hepatic FC (8.2 ± 2.0% vs. 8.1 ± 0.8%/day; P = 0.72) was not significantly different between diabetic and control subjects.

CONCLUSIONS

Despite long-standing disease, lipogenesis and cholesterol synthesis was not different in individuals with type 1 diabetes compared to healthy non-diabetic humans.

Vitamin C further improves the protective effect of glucagon-like peptide-1 on acute hypoglycemia-induced oxidative stress, inflammation, and endothelial dysfunction in type 1 diabetes

OBJECTIVE

To test the hypothesis that acute hypoglycemia induces endothelial dysfunction and inflammation through the generation of an oxidative stress. Moreover, to test if the antioxidant vitamin C can further improve the protective effects of glucagon-like peptide 1 (GLP-1) on endothelial dysfunction and inflammation during hypoglycemia in type 1 diabetes.

RESEARCH DESIGN AND METHODS

A total of 20 type 1 diabetic patients underwent four experiments: a period of 2 h of acute hypoglycemia with or without infusion of GLP-1 or vitamin C or both. At baseline, after 1 and 2 h, glycemia, plasma nitrotyrosine, plasma 8-iso prostaglandin F2a (PGF2a), soluble intracellular adhesion molecule-1a (sICAM-1a), interleukin-6 (IL-6), and flow-mediated vasodilation were measured. At 2 h of hypoglycemia, flow-mediated vasodilation significantly decreased, while sICAM-1, 8-iso-PGF2a, nitrotyrosine, and IL-6 significantly increased. The simultaneous infusion of GLP-1 or vitamin C significantly attenuated all of these phenomena. Vitamin C was more effective. When GLP-1 and vitamin C were infused simultaneously, the deleterious effect of hypoglycemia was almost completely counterbalanced.

RESULTS

At 2 h of hypoglycemia, flow-mediated vasodilation significantly decreased, while sICAM-1, 8-iso-PGF2a, nitrotyrosine, and IL-6 significantly increased. The simultaneous infusion of GLP-1 or vitamin C significantly attenuated all of these phenomena. Vitamin C was more effective. When GLP-1 and vitamin C were infused simultaneously, the deleterious effect of hypoglycemia was almost completely counterbalanced.

CONCLUSIONS

This study shows that vitamin C infusion, during induced acute hypoglycemia, reduces the generation of oxidative stress and inflammation, improving endothelial dysfunction, in type 1 diabetes. Furthermore, the data support a protective effect of GLP-1 during acute hypoglycemia, but also suggest the presence of an endothelial resistance to the action of GLP-1, reasonably mediated by oxidative stress.

Exercise and type 1 diabetes (T1DM)

Physical exercise is firmly incorporated in the management of type 1 diabetes (T1DM), due to multiple recognized beneficial health effects (cardiovascular disease prevention being preeminent). When glycemic values are not excessively low or high at the time of exercise, few absolute contraindications exist; practical guidelines regarding amount, type, and duration of age-appropriate exercise are regularly updated by entities such as the American Diabetes Association and the International Society for Pediatric and Adolescent Diabetes. Practical implementation of exercise regimens, however, may at times be problematic. In the poorly controlled patient, specific structural changes may occur within skeletal muscle fiber, which is considered by some to be a disease-specific myopathy. Further, even in well-controlled patients, several homeostatic mechanisms regulating carbohydrate metabolism often become impaired, causing hypo- or hyperglycemia during and/or after exercise. Some altered responses may be related to inappropriate exogenous insulin administration, but are often also partly caused by the "metabolic memory" of prior glycemic events. In this context, prior hyperglycemia correlates with increased inflammatory and oxidative stress responses, possibly modulating key exercise-associated cardio-protective pathways. Similarly, prior hypoglycemia correlates with impaired glucose counterregulation, resulting in greater likelihood of further hypoglycemia to develop. Additional exercise responses that may be altered in T1DM include growth factor release, which may be especially important in children and adolescents. These multiple alterations in the exercise response should not discourage physical activity in patients with T1DM, but rather should stimulate the quest for the identification of the exercise formats that maximize beneficial health effects.

Glucagon-like peptide 1 reduces endothelial dysfunction, inflammation, and oxidative stress induced by both hyperglycemia and hypoglycemia in type 1 diabetes

OBJECTIVE

Hyperglycemia and hypoglycemia currently are considered risk factors for cardiovascular disease in type 1 diabetes. Both acute hyperglycemia and hypoglycemia induce endothelial dysfunction and inflammation, raising the oxidative stress. Glucagon-like peptide 1 (GLP-1) has antioxidant properties, and evidence suggests that it protects endothelial function.

RESEARCH DESIGN AND METHODS

The effect of both acute hyperglycemia and acute hypoglycemia in type 1 diabetes, with or without the simultaneous infusion of GLP-1, on oxidative stress (plasma nitrotyrosine and plasma 8-iso prostaglandin F2alpha), inflammation (soluble intercellular adhesion molecule-1 and interleukin-6), and endothelial dysfunction has been evaluated.

RESULTS

Both hyperglycemia and hypoglycemia acutely induced oxidative stress, inflammation, and endothelial dysfunction. GLP-1 significantly counterbalanced these effects.

CONCLUSIONS

These results suggest a protective effect of GLP-1 during both hypoglycemia and hyperglycemia in type 1 diabetes.

On the importance of global cardiovascular risk assessment in people with type 2 diabetes

This narrative review examines the concept of diabetes as a cardiovascular disease (CVD) risk equivalent, the rationale and approaches to absolute CVD risk estimation in type 2 diabetes. In people with diabetes, CVD risk follows a gradient. Reliably capturing this gradient depends on the combination of several risk factors. Existing CVD risk tools applicable to people with diabetes have shown a modest-to-acceptable performance. Future improvements may include updating existing models or constructing new ones with improved predictive accuracy. Ultimately, developed models should be tested in independent populations, and the impact of their uptake on clinical decision making and the outcome of care assessed.

Vitamin C further improves the protective effect of GLP-1 on the ischemia-reperfusion-like effect induced by hyperglycemia post-hypoglycemia in type 1 diabetes

Background

It has been reported that hyperglycemia following hypoglycemia produces an ischemia-reperfusion-like effect in type 1 diabetes. In this study the possibility that GLP-1 has a protective effect on this phenomenon has been tested.

Methods

15 type 1 diabetic patients underwent to five experiments: a period of two hours of hypoglycemia followed by two hours of normo-glycemia or hyperglycemia with the concomitant infusion of GLP-1 or vitamin C or both. At baseline, after 2 and 4 hours, glycemia, plasma nitrotyrosine, plasma 8-iso prostaglandin F2alpha, sCAM-1a, IL-6 and flow mediated vasodilation were measured.

Results

After 2 h of hypoglycemia, flow mediated vasodilation significantly decreased, while sICAM-1, 8-iso-PGF2a, nitrotyrosine and IL-6 significantly increased. While recovering with normoglycemia was accompanied by a significant improvement of endothelial dysfunction, oxidative stress and inflammation, a period of hyperglycemia after hypoglycemia worsens all these parameters. These effects were counterbalanced by GLP-1 and better by vitamin C, while the simultaneous infusion of both almost completely abolished the effect of hyperglycemia post hypoglycemia.

Conclusions

This study shows that GLP-1 infusion, during induced hyperglycemia post hypoglycemia, reduces the generation of oxidative stress and inflammation, improving the endothelial dysfunction, in type 1 diabetes. Furthermore, the data support that vitamin C and GLP-1 may have an additive protective effect in such condition.

Cardiovascular disease in children and adolescents with diabetes: where are we, and where are we going?

The increasing prevalence of type 1 and type 2 diabetes mellitus combined with advancement in early detection of cardiovascular disease (CVD) has placed CVD as a significant concern for preventative pediatric medicine. The public health burden of type 2 diabetes is predicted to parallel increasing obesity in children with a projected increase of early CVD in adulthood. In this article, we review practice guidelines for cardiovascular health in children and adolescents with diabetes and data on which they are based. We then focus on imaging modalities that are promising tools to expand our understanding of the cardiovascular risk imposed on youths with diabetes.

Complications of type 1 diabetes

The prevalence of diabetes is increasing worldwide and the concern regarding the number of new cases of diabetes relates to the development of chronic complications. It has been recognized for years that the complications are a cause of considerable morbidity and mortality worldwide and as such, negatively affect the quality of life in individuals with diabetes with an increase in disability and death. Specifically, the complications of diabetes have been classified as either microvascular (ie, retinopathy, nephropathy, and neuropathy) or macrovascular (ie, cardiovascular disease, cerebrovascular accidents, and peripheral vascular disease). For purposes of this article, the authors focus on a brief review of the major complications.