Insulin sensitivity and arterial stiffness in youth with type 1 diabetes: the SEARCH CVD study

Cardiovascular diseases consequences of type 1, type 2 diabetes mellitus and glycemic traits: A Mendelian randomization study

OBJECTIVE

This Mendelian randomization (MR) study aimed to investigate the relationships between type 1 diabetes (T1D), type 2 diabetes (T2D), and glycemic traits, including fasting insulin, fasting glucose, and HbA1c, with cardiovascular diseases (CVDs).

METHODS

We selected genetic instruments for predisposition to T1D, T2D, fasting insulin, fasting glucose, and HbA1c based on published genome-wide association studies. Using a 2-Sample MR approach, we assessed associations with 12 common CVDs sourced from the FinnGen and UK Biobank studies, along with stroke subtypes obtained from the GIGASTROKE and MEGASTROKE Consortium.

RESULTS

T1D was associated with SVS. T2D showed associations with AIS, LAA, CES, SVS, coronary heart disease, myocardial infarction, pulmonary embolism, DVT of lower extremities, peripheral vascular diseases. Genetically predicted higher HbA1c levels were associated with eight CVDs. The results of MVMR aligned with the primary findings for T1D and T2D.

CONCLUSIONS

T1D and T2D exhibit different genetic predisposition to CVDs. BMI, LDL, and HDL play intermediary roles in connecting TID and T2D to specific types of CVDs, providing insights into the potential underlying pathways and mechanisms involved in these relationships. Strategies aimed at achieving sustained reductions in HbA1c levels may offer potential for reducing the risk of various CVDs.

Evaluation of changes in glycemic control and diabetic complications over time and factors associated with the progression of diabetic complications in Japanese patients with juvenile-onset type 1 diabetes mellitus

BACKGROUND

This study aimed to evaluate the changes in glycemic control and diabetic complications over time in Japanese patients with juvenile-onset type 1 diabetes mellitus and to clarify the factors associated with the progression of diabetic complications.

METHODS

We tracked 129 patients with type 1 diabetes mellitus (21.8 ± 4.1 years old [mean ± SD] with a diabetes duration of 12.6 ± 5.7 years) for up to 19 years and analyzed data on glycated hemoglobin (HbA1c) and indicators related to the severity of diabetic complications (estimated glomerular filtration rate [eGFR], urinary albumin excretion rate [UAE], carotid intima-media thickness [CIMT], and brachial-ankle pulse wave velocity [baPWV]) using linear mixed model and decision tree analysis.

RESULTS

Although the HbA1c and UAE levels improved over time, the eGFR, CIMT, and baPWV worsened. Decision tree analysis showed that HbA1c and the glycoalbumin/HbA1c ratio for eGFR; HbA1c and systolic blood pressure for UAE; low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio, glycoalbumin/HbA1c ratio, and body mass index (BMI) for CIMT; and HbA1c for baPWV were associated factors.

CONCLUSIONS

In this retrospective observational study, glycemic control and albuminuria improved; however, renal function and arteriosclerosis worsened over time. HbA1c levels, glycemic excursion, and blood pressure are associated with nephropathy progression. HbA1c levels, glycemic excursion, lipid levels, and BMI are associated with the progression of atherosclerosis.

Risk factors for pre-clinical atherosclerosis in adolescents with type 1 diabetes

AIMS

To assess whether, besides "traditional" risk factors, overall oxidative stress, oxidized lipoproteins, and glycemic variability are associated with early macro-vascular damage in type 1 diabetes (T1D).

METHODS

In 267 children/adolescents with T1D (130 girls, age 9.1-23.0 years) we evaluated: derivatives of reactive oxygen metabolites [d-ROMs], serum total antioxidant capacity [TAC] and oxidized LDL-cholesterol [oxLDL]; markers of early vascular damage (Lipoprotein-associated phospholipase A2 [Lp-PLA2], z-score of carotid intima-media thickness [z-cIMT] and carotid-femoral pulse wave velocity [z-PWV]); CGM metrics of four weeks preceding the visit, central systolic/diastolic blood pressures (cSBP/cDBP), and HbA1c, z-score of BP (z-SBP/z-DBP) and circulating lipids longitudinally collected since T1D onset.. Three general linear models were built with z-cIMT, z-PWV adjusted for current cDBP, and Lp-PLA2 as independent variables.

RESULTS

The z-cIMT was associated with male gender (B = 0.491, η² = 0.029, p = 0.005), cSBP (B = 0.023, η² = 0.026, p = 0.008) and oxLDL (B = 0.022, η² = 0.022, p = 0.014). The z-PWV was associated with diabetes duration (B = 0.054, η² = 0.024, p = 0.016), daily insulin dose (B = 0.52, η² = 0.018, p = 0.045), longitudinal z-SBP (B = 0.18, η² = 0.018, p = 0.045) and dROMs (B = 0.003, η² = 0.037, p = 0.004). Lp-PLA2 was associated with age (B = 0.221, η² = 0.079, p = 3*10^-6), oxLDL (B = 0.081, η² = 0.050, p = 2*10^-4), longitudinal LDL-cholesterol (B = 0.031, η² = 0.043, p = 0.001) and male gender (B = -1.62, η² = 0.10, p = 1.3*10⁷).

CONCLUSIONS

Oxidative stress, male gender, insulin dose, diabetes duration and longitudinal lipids and blood pressure, contributed to the variance of early vascular damage in young patients with T1D.

Is There a Role for Imaging Youth at Risk of Atherosclerosis?

PURPOSE OF REVIEW

Cardiovascular (CV) risk factors such as dyslipidemia, hypertension, diabetes, and obesity are associated with an increased risk for CV events in adults. Noninvasive measures of vascular health are associated with these CV events and can potentially help risk stratify children with CV risk factors. The purpose of this review is to summarize recent literature regarding vascular health in children with cardiovascular risk factors.

RECENT FINDINGS

Adverse changes in pulse wave velocity, pulse wave analysis, arterial distensibility, and carotid intima-media thickness are seen in children with CV risk factors supporting potential utility in risk stratification. Assessing vascular health in children can be challenging due to growth-related changes in vasculature, multiple assessment modalities, and differences in normative data. Vascular health assessment in children with cardiovascular risk factors can be a valuable tool for risk stratification and help identify opportunities for early intervention. Future areas of research include increasing normative data, improving conversion of data between different modalities, and increasing longitudinal studies in children linking childhood risk factors to adult CV outcomes.

Impact of overweight and obesity on epicardial adipose tissue in children with type 1 diabetes

OBJECTIVES

Epicardial adipose tissue (EAT) thickness, a novel marker of cardiovascular disease (CVD), is increased in children with a healthy weight and type 1 diabetes (T1D). The prevalence of obesity has increased in children with T1D and may confer additional CVD risk. The purpose of this study was to examine EAT thickness in youth with and without T1D in the setting of overweight/obesity.

METHODS

Youth with overweight/obesity and T1D (n=38) or without T1D (n=34) between the ages of 6-18 years were included in this study. Echocardiogram using spectral and color flow Doppler was used to measure EAT and cardiac function. Waist circumference, blood pressure, and HbA_1c, were used to calculate estimated glucose disposal rate (eGDR) to estimate insulin resistance in children with T1D.

RESULTS

EAT thickness was not significantly different in youth with T1D compared to controls (2.10 ± 0.67 mm vs. 1.90 ± 0.59 mm, p=0.19). When groups were combined, EAT significantly correlated with age (r=0.449, p≤0.001), BMI (r=0.538, p≤0.001), waist circumference (r=0.552, p≤0.001), systolic BP (r=0.247, p=0.036), myocardial performance index (r=-0.287, p=0.015), ejection fraction (r=-0.442, p≤0.001), and cardiac output index (r=-0.306, p=0.009). In the group with T1D, diastolic BP (r=0.39, p=0.02) and eGDR (r=-0.48, p=0.002) correlated with EAT.

CONCLUSIONS

EAT was associated with measures of adiposity and insulin resistance but does not differ by diabetes status among youth with overweight/obesity. These findings suggest that adiposity rather than glycemia is the main driver of EAT thickness among youth with T1D.

The association of insulin resistance measured through the estimated glucose disposal rate with predictors of micro-and macrovascular complications in patients with type 1 diabetes

BACKGROUND AND AIM

Insulin resistance (IR) is associated with a higher rate of type 1 diabetes (T1D) complications. We aimed to examine the relationship between estimated glucose disposal rate (eGDR), a readily available marker of IR in clinical practice and early predictor biomarkers of macrovascular and microvascular complications in patients with T1D.

DESIGN

A cross-sectional study.

METHODS

A total of 165 consecutive patients with T1D free of cardiovascular, eye, and renal complications were included in the study from 2016 to 2020. Participants were characterized as insulin resistant if their eGDR value was ≤ 8 mg/kg/min. Pulse wave velocity (PWV) and global longitudinal strain (GLS) were used as surrogates for subclinical atherosclerosis and left ventricular systolic dysfunction (LVSD), respectively. Four previously standardized tests based on the calculation of heart rate variability (HRV) were used to evaluate subclinical cardiac autonomic neuropathy (CAN). Early nephropathy was assessed by assessing urinary albumin to creatinine ratio (ACR).

RESULTS

The population sample (n = 165) included a majority of female patients (63%) and had a median age of 32 years (24-43), median disease duration of 14 years ( ± 9.5-21.5), a median BMI value of 23.7 kg/m² (21.4-26.6), an HbA1C of 7.2% (6.7-8.2) and median eGDR (lower values indicate higher insulin resistance) of 9.2 mg/kg/min (8.2-9.9), while 21.8% (n = 36) of the participants were characterized as insulin resistant. After adjustment for age, gender, and the duration of diabetes, the presence of IR was significantly associated with higher prevalence of subclinical atherosclerosis (OR:2.59, 95% CI: 1.06-6.30, p = 0.036), CAN (OR:3.07, 95% CI: 1.02-9.32, p = 0.047) and subclinical LVSD (OR: 4.9, 95% CI: 1.94-12.79, p = 0.001). No association was shown with ACR.

CONCLUSIONS

In patients with T1D, insulin resistance, as measured by eGDR, correlates well with early CVD predictors and CAN. These associations appear independent of the effects of gender, aging, and disease duration.

Longitudinal Changes in Arterial Stiffness and Heart Rate Variability in Youth-Onset Type 1 Versus Type 2 Diabetes: The SEARCH for Diabetes in Youth Study

OBJECTIVE

We compared arterial stiffness and heart rate variability (HRV) over time by diabetes type and determined the risk factors associated with worsening arterial stiffness and HRV in young adults with youth-onset diabetes.

RESEARCH DESIGN AND METHODS

Arterial stiffness (pulse wave velocity, augmentation index) and six indices of heart rate variability were measured twice, 4.5 years apart, among participants with either youth-onset type 1 or type 2 diabetes in the SEARCH for Diabetes in Youth study. Multivariable linear regression models were used to assess risk factors associated with arterial stiffness and HRV at follow-up.

RESULTS

Of 1,159 participants studied, 949 had type 1 diabetes (mean age 17.1 ± 4.7 years, 60.3% non-Hispanic White, 55% female) and 210 had type 2 diabetes (mean age 22.1 ± 3.5 years, 23.8% non-Hispanic White, 71% female) at initial assessment when diabetes duration was 7.9 years (both groups). Participants with type 2 versus type 1 diabetes had greater arterial stiffness and more abnormalities in HRV at initial and follow-up assessment and a greater change over time (all P < 0.05). Risk factors associated with worse arterial stiffness and HRV at follow-up in both types of diabetes included higher blood pressure, hemoglobin A1c, waist circumference, and triglycerides over time and longer diabetes duration.

CONCLUSIONS

Arterial stiffness and HRV worsened over time with greater changes among participants with type 2 versus type 1 diabetes and among those with features of the metabolic syndrome. The risk factor profile documents potentially modifiable pathways to prevent or limit cardiovascular complications in young adults with youth-onset diabetes.

Predictors of arterial stiffness in adolescents and adults with type 1 diabetes: a cross-sectional study

INTRODUCTION

Individuals with type 1 diabetes have increased arterial stiffness compared with age-matched healthy controls. Our aim was to determine which hemodynamic and demographic factors predict arterial stiffness in this population.

RESEARCH DESIGN AND METHODS

Carotid-femoral pulse wave velocity (cfPWV) was examined in 41 young adults and adolescents with type 1 diabetes without microvascular complications. Two ordinary least squares regression analyses were performed to determine multivariate relationships between cfPWV (loge) and (1) age, duration of diabetes, sex, and hemoglobin A1c and (2) augmentation index (AIx), mean arterial pressure, flow-mediated dilation (FMD), and heart rate. We also examined differences in macrovascular outcome measures between sexes.

RESULTS

Age, sex, and FMD provided unique predictive information about cfPWV in these participants with type 1 diabetes. Despite having similar cardiovascular risk factors, men had higher cfPWV compared with women but no differences were observed in other macrovascular outcomes (including FMD and AIx).

CONCLUSIONS

Only age, sex, and FMD were uniquely associated with arterial stiffness in adolescents and adults with uncomplicated type 1 diabetes. Women had less arterial stiffness and similar nitric oxide-dependent endothelial function compared with men. Larger, prospective investigation is warranted to determine the temporal order of and sex differences in arterial dysfunction in type 1 diabetes.

Arterial Stiffness and Type 1 Diabetes: The Current State of Knowledge

The most common cause of mortality among people with type 1 diabetes is cardiovascular diseases. Arterial stiffness allows predicting cardiovascular complications, cardiovascular mortality, and all-cause mortality. There are different ways to measure arterial stiffness; the gold standard is pulse wave velocity. Arterial stiffness is increased in people with type 1 diabetes compared to healthy controls. It increases with age and duration of type 1 diabetes. Arterial stiffness among people with type 1 diabetes positively correlates with systolic blood pressure, obesity, glycated hemoglobin, waist circumference, and waist to hip ratio. It has a negative correlation with the estimated glomerular filtration rate, high-density lipoprotein, and the absence of carotid plaques. The increased arterial stiffness could result from insulin resistance, collagen increase due to inadequate enzymatic glycation, and endothelial and autonomic dysfunction. The insulin-induced decrease in arterial stiffness is impaired in type 1 diabetes. There are not enough proofs to use pharmacotherapy in the prevention of arterial stiffness, but some of the medicaments got promising results in single studies, for example, renin-angiotensin-aldosterone system inhibitors, statins, and SGLT2 inhibitors. The main strategy of prevention of arterial stiffness progression remains glycemic control and a healthy lifestyle.

Nutrition and Obesity in the Pathogenesis of Youth-Onset Type 1 Diabetes and Its Complications

Since the 1980s, there has been a dramatic rise in the prevalence of overweight and obesity in pediatric populations, in large part driven by sedentary lifestyles and changing dietary patterns with more processed foods. In parallel with the rise in pediatric obesity in the general population, the prevalence of overweight and obesity has increased among children and adolescents with type 1 diabetes. Adiposity has been implicated in a variety of mechanisms both potentiating the risk for type 1 diabetes as well as exacerbating long-term complications, particularly cardiovascular disease. Treatment options targeting the unique needs of obese pediatric patients, both before and after diagnosis of type 1 diabetes, are limited. In this review, we discuss the history of the epidemiology of the obesity epidemic in the context of pediatric type 1 diabetes, highlight the possible role of obesity in type 1 diabetes pathogenesis and review the concept of "double diabetes". The impact of obesity at and after diagnosis will be discussed, including noted differences in clinical and biochemical markers, lipid abnormalities, and long-term cardiovascular complications. Finally, we will review the existing literature on pharmacologic and nutritional interventions as potential treatment strategies for youth with coexisting type 1 diabetes and obesity.

Vascular Effects of ACE (Angiotensin-Converting Enzyme) Inhibitors and Statins in Adolescents With Type 1 Diabetes

An increased albumin-creatinine ratio within the normal range can identify adolescents at higher risk of developing adverse cardio-renal outcomes as they progress into adulthood. Utilizing a parallel randomized controlled trial and observational cohort study, we characterized the progression of vascular phenotypes throughout this important period and investigated the effect of ACE (angiotensin-converting enzyme) inhibitors and statins in high-risk adolescents. Endothelial function (flow-mediated dilation and reactive hyperemia index) and arterial stiffness (carotid-femoral pulse wave velocity) were assessed in 158 high-risk participants recruited to a randomized, double-blind placebo-controlled 2×2 factorial trial (randomized, placebo-controlled trial) of ACE inhibitors and/or statins in adolescents with type 1 diabetes (AdDIT [Adolescent Type 1 Diabetes cardio-renal Intervention Trial]). Identical measures were also assessed in 215 lower-risk individuals recruited to a parallel observational study. In the randomized, placebo-controlled trial, high-risk patients randomized to ACE inhibitors had improved flow-mediated dilation after 2 to 4 years of follow-up (mean [95% CI]: 6.6% [6.0-7.2] versus 5.3% [4.7-5.9]; P=0.005), whereas no effect was observed following statin use (6.2% [5.5-6.8] versus 5.8% [5.1-6.4]; P=0.358). In the observational study, patients classed as high-risk based on albumin-creatinine ratio showed evidence of endothelial dysfunction at the end of follow-up (flow-mediated dilation=4.8% [3.8-5.9] versus 6.3% [5.8-6.7] for high-risk versus low-risk groups; P=0.015). Neither reactive hyperemia index nor pulse wave velocity were affected by either treatment (P>0.05 for both), but both were found to increase over the duration of follow-up (0.07 [0.03-0.12]; P=0.001 and 0.5 m/s [0.4-0.6]; P<0.001 for reactive hyperemia index and pulse wave velocity, respectively). ACE inhibitors improve endothelial function in high-risk adolescents as they transition through puberty. The longer-term protective effects of this intervention at this early age remain to be determined. Registration- URL: https://www.clinicaltrials.gov; Unique identifier NCT01581476.

Cardiovascular disease in young People with Type 1 Diabetes: Search for Cardiovascular Biomarkers

Premature onset of cardiovascular disease is common in people with type 1 diabetes and is relatively understudied in youth. Several reports in adolescents and young adults with diabetes demonstrate evidence of arterial stiffness and cardiac dysfunction, yet critical gaps exist in our current understanding of the temporal progression of cardiac and vascular dysfunction in these youth, and mechanistic investigations with robust pathophysiologic assessment are lacking. This review attempts to summarize relevant cardiovascular studies concerning children, adolescents, and young adults with type 1 diabetes. We focus on imaging-based biomarkers routinely applied to youth and adults that are well-established in their ability to predict adjudicated cardiovascular outcomes, and their relevant physiologic interpretation. Particularly, we focus the attention to 1) cardiac ventricular strain imaging techniques which are known to be predictive of clinical outcomes in patients with heterogenous causes of heart failure, and 2) stiffness in large arteries, a well-established prognostic marker of cardiovascular events. We conclude that there remains an urgent need for sensitive and quantitative biomarkers to define the natural history of cardiac and vascular disease origination and progression in type 1 diabetes, and set the stage for interpreting interventional studies focused on preventing, reversing or slowing disease progression.

Motivational Interview to improve vascular health in Adolescents with poorly controlled type 1 Diabetes (MIAD): a randomized controlled trial

INTRODUCTION

We studied if motivational interviewing (MI) added to standard educational care (SEC) improves vascular health in adolescents with poorly controlled type 1 diabetes.

RESEARCH DESIGN AND METHODS

47 adolescents with type 1 diabetes of at least 2 years duration and hemoglobin A1c >75 mmol/mol (>9.0%) on two visits were randomized to MI+SEC or SEC. We also compared vascular health parameters of patients with type 1 diabetes at trial baseline with a group of healthy historical controls matched for age and body size.

RESULTS

39 adolescents (20 MI+SEC) completed the vascular health study. At 12 months, parameter changes were not statistically significantly different between MI+SEC and SEC (carotid-femoral pulse wave velocity (cfPWV): mean difference 0.052 m/s (95% CI -0.395 to 0.500, p=0.81); carotid-radial PWV (crPWV): 0.118 m/s (95% to 0.478 to 0.713, p=0.69), carotid intima-media thickness (IMT): 0.002 mm (95% CI -0.37 to 0.40, p=0.93), systolic blood pressure (BP) z-score: 0.495 (95% CI -0.099 to 1.09, p=0.10). At baseline, duration of type 1 diabetes was associated with radial IMT (r=0.430, p=0.007) and cfPWV (r=0.373, p=0.018), and carotid, femoral and brachial IMT were correlated with continuous glucose monitoring (CGM) SD (r=0.440, p=0.017; r=0.377, p=0.048; r=0.387, p=0.038). There was an inverse association between CGM time-in-range (3.9-10.0 mmol/L) and crPWV (r=-0.476, p=0.022) changes. Systolic BP change was associated with body mass index change (r=0.374, p=0.019) and IMT change (r=0.461, p=0.016 for carotid IMT; r=0.498, p=0.010 for femoral IMT). PWVs were higher and common carotid compliance lower among patients with type 1 diabetes at baseline compared with healthy controls, but no other differences were found.

CONCLUSION

There was no effect of MI added to SEC on vascular health parameters. Although disease duration and glycemic control were associated with vascular health at baseline, there were only limited associations between glycemic control and vascular health parameter changes. Vascular health parameter changes were interrelated suggesting clustering of cardiovascular risk.

TRIAL REGISTRATION NUMBER

NCT02637154.

Subclinical macroangiopathic target organ damage in type 1 diabetes mellitus patients

PURPOSE

We have summarized key studies regarding the assessment of subclinical macroangiopathic target organ damage (TOD) in type 1 diabetes mellitus (T1DM).

RESULTS

Although chronic complications resulting from hyperglycemia, in particular macroangiopathies, are still the first cause of death in T1DM, there has been growing recognition of the role of hypoglycemia in cardiovascular morbidity and mortality. Subclinical TOD diagnosis ensures early implementation of the complex management aiming at either partial reversal of these complications or at least its downturn. To better identify patients with early TODs, several non-invasive diagnostic techniques are employed, including the ultrasonographic assessment of the intima-media thickness (IMT), computed tomography (CT) for coronary artery calcium (CAC) scores, and pulse wave velocity (PWV) measurement for arterial stiffness evaluation. Various studies reported that T1DM patients present an increased IMT. An increasing IMT fairly correlates with the cardiovascular (CV) events risk even after the adjustment to age, diabetes duration, quality of glucose control as well as the presence of hypertension, and chronic complications. Another, well established marker of the organ damage - CAC score is recommended by ACC/AHA guidelines to assess the overall CV risk in T1DM. Also, the arterial stiffness evaluation with PWV may further improve CV risk prediction, which has been reported in multiple studies including the Framingham Heart Study.

CONCLUSIONS

There is shortage of data from prospective studies which could confirm the benefits of early treatment initiation based on the presence of the subclinical organ damage in T1DM. Most evidence comes from T2DM trials, where effective preventive measures were identified i.e.: smoking cessation, reasonable blood glucose control, efficacious hypertension treatment, and dyslipidemia management, as well as renoprotection. There is still a field for further research to see if routine assessment of asymptomatic vascular damage and early implementation of aggressive treatment would reduce mortality excess from CVD in T1DM.

Exercise effects on arterial stiffness and heart health in children with excess weight: The SMART RCT

INTRODUCTION

Childhood obesity and inactivity are associated with cardiovascular risk. Evidence is limited for exercise effects on arterial health in children.

METHODS

One hundred and seventy-five inactive children with overweight or obesity (8-11 years, ≥85th percentile BMI, 61% female, 87% Black, 73% with obesity) were randomized to an 8-month daily after-school aerobic exercise program (40 min/day, n = 90) or a sedentary control condition (n = 85). Carotid-femoral pulse wave velocity (PWV, primary outcome, arterial stiffness), fitness, adiposity, blood pressure (BP), glucose, insulin resistance, lipids, and C-reactive protein were measured at baseline and posttest (8 months). Adiposity, fitness, and BP were measured again at follow-up, 8-12 months later. Intent-to-treat analyses were conducted using mixed models.

RESULTS

The study had 89% retention, with attendance of 59% in exercise and 64% in the control condition, and vigorous exercise participation (average heart rate 161 ± 7 beats/min). Compared with controls, the exercise group had twice the improvement in fitness (VȮ2 peak, 2.7 (95% CI 1.8, 3.6) vs. 1.3 (0.4, 2.3) mL/kg/min) and adiposity (-1.8 (-2.4, -1.1) vs. -0.8 (-1.5, -0.1)%), each p = 0.04, and a large improvement in HDL-cholesterol (0.13 (0.075, 0.186) vs. -0.028 (-0.083, 0.023) mmol/L, p < 0.0001). There was no group × time effect on other outcomes at 8 months, or on any outcomes at follow-up. The change in PWV at 8 months correlated with changes in insulin and insulin resistance (both r = 0.32), diastolic BP (r = 0.24), BMI (r = 0.22), and adiposity (r = 0.18).

CONCLUSIONS

Eight months of aerobic exercise training improved fitness, adiposity, and HDL-cholesterol levels, but did not reduce arterial stiffness in children with excess weight. PWV improved as a function of insulin resistance, BP, BMI, and adiposity. Weight loss may be required to improve arterial stiffness. Exercise benefits waned after discontinuing the program.

Association of metformin and statin medications with surrogate measures of cardiovascular disease in youth with type 1 diabetes: the SEARCH for diabetes in youth study

PURPOSE

Youth with type 1 diabetes mellitus (T1DM) are at risk of cardiovascular disease (CVD). We evaluated if metformin or statin use was associated with surrogate measures of improved CVD.

METHODS

We included participants from the SEARCH observational study. Participants treated with insulin plus metformin (n=42) or insulin plus statin (n=39) were matched with 84 and 78 participants, respectively, treated with insulin alone. Measures of arterial stiffness obtained were pulse wave velocity (PWV), augmentation index (AI75), and heart rate variability as standard deviation of the normal-to-normal interval (SDNN) and root mean square differences of successive NN intervals (RMSSD).

RESULTS

CVD measures were not significantly different among participants on insulin plus metformin versus those on insulin alone: PWV (5.9±1.0 m/sec vs. 5.8±1.5 m/sec, P=0.730), AI75 (1.8 [-6.0 to 8.0] vs. -2.4 [-10.7 to 3.8], P=0.157), SDNN (52.4 [36.8-71.1] m/sec vs. 51.8 [40.1-74.9] m/sec, P=0.592), and RMSSD (43.2 [29.4-67.6] vs. 47.4 [28.0-76.3], P=0.952). CVD measures were not different for statin users versus nonusers: PWV (5.7±0.8 m/sec vs. 5.9 ±1.1 m/sec, P=0.184), AI75 ( -4.0 [-9.5 to 1.7] vs. -6.7 [-11.3 to 5.7], P=0.998), SDNN (54.6 [43.5-77.2] m/sec vs. 63.1 [44.2-86.6] m/sec, P=0.369), and RMSSD (49.5 [31.2-74.8] vs. 59.2 [38.3-86.3], P=0.430).

CONCLUSION

We found no associations of statin or metformin use with surrogate measures of CVD. Future prospective pediatric clinical trials could address this issue.

Subclinical vascular disease in patients with diabetes is associated with insulin resistance

Patients with diabetes experience increased cardiovascular risk that is not fully explained by deficient glycemic control or traditional cardiovascular risk factors such as smoking and hypercholesterolemia. Asymptomatic patients with diabetes show structural and functional vascular damage that includes impaired vasodilation, arterial stiffness, increased intima-media thickness and calcification of the arterial wall. Subclinical vascular injury associated with diabetes predicts subsequent manifestations of cardiovascular disease, such as ischemic heart disease, peripheral artery disease and stroke. Noninvasive detection of subclinical vascular disease is commonly used to estimate cardiovascular risk associated to diabetes. Longitudinal studies in normotensive subjects show that arterial stiffness at baseline is associated with a greater risk for future hypertension independently of established risk factors. In patients with type 2 diabetes, vascular disease begins to develop during the latent phase of insulin resistance, long before the clinical diagnosis of diabetes. In contrast, patients with type 1 diabetes do not manifest vascular injury when they are first diagnosed due to insulin deficiency, as they lack the preceding period of insulin resistance. These findings suggest that insulin resistance plays an important role in the development of early vascular disease associated with diabetes. Cross-sectional and prospective studies confirm that insulin resistance is associated with subclinical vascular injury in patients with diabetes, independently of standard cardiovascular risk factors. Asymptomatic vascular disease associated with diabetes begins to occur early in life having been documented in children and adolescents. Insulin resistance should be considered a therapeutic target in order to prevent the vascular complications associated with diabetes.

Insulin resistance is a cardiovascular risk factor in humans

Diabetes is a common metabolic disorder associated to elevated cardiovascular morbidity and mortality that is not explained by hyperglycemia or traditional cardiovascular risk factors such as smoking or hypercholesterolemia. Intensive glycemic control with insulin that achieves near-normal glycemia does not reduce significantly macrovascular complications compared with conventional glycemic control. Cardiovascular disease continues to develop in patients with diabetes despite adequate glycemic control. In contrast, intensive control with metformin (leading to insulin resistance improvement) reduces diabetes complications, including cardiovascular events, suggesting that enhancement of insulin sensitivity rather than plasma glucose level has a major role improving diabetes outcomes. Accordingly, insulin resistance estimated by glucose tolerance tests is better predictor of future cardiovascular events than fasting glucose level in nondiabetic individuals. Insulin resistance precedes for decades the clinical onset of type 2 diabetes and deteriorates metabolic control of type 1 diabetes. Numerous investigations including cross-sectional and prospective studies, meta-analyses, and systematic reviews provide compelling evidence that insulin resistance by itself is a cardiovascular risk factor in a variety of population groups, including the general population and patients with diabetes. Several estimations of insulin resistance have been consistently associated with elevated rate of cardiovascular events independently of other cardiovascular risk factors and diabetes status. The clinical expression of insulin resistance (the metabolic syndrome or any of its components including obesity, hyperinsulinemia, hypertension, and dyslipemia) has been related to cardiovascular disease as well. An estimation conducted by the Archimedes model confirms that insulin resistance is the most important single cause of coronary artery disease.

Youth With Type 1 Diabetes Have Adipose, Hepatic, and Peripheral Insulin Resistance

CONTEXT

Adolescents with type 1 diabetes (T1D) have difficulty obtaining optimal glucose control, which may relate to insulin resistance (IR), especially during puberty. Moreover, IR increases the risk for cardiovascular disease, the leading cause of death in T1D. However, the tissue specificity of IR in adolescents with T1D has not been fully phenotyped.

OBJECTIVE

To assess adipose, hepatic, and peripheral insulin sensitivity in adolescents with and without T1D.

DESIGN AND SETTING

Thirty-five youth with T1D [median age, 16 (first and third quartiles, 14, 17) years; 53% female; median body mass index (BMI) percentile, 82nd (55th, 96th); late puberty; median hemoglobin A1c, 8.3% (7.3%, 9.4%)] and 22 nondiabetic youth of similar age, BMI, pubertal stage, and level of habitual physical activity were enrolled. Insulin action was measured with a four-phase hyperinsulinemic euglycemic clamp (basal and 10, 16, and 80 mU/m2/min) with glucose and glycerol isotope tracers.

RESULTS

Adolescents with T1D had a significantly higher rate of lipolysis (P < 0.0001) and endogenous glucose production (P < 0.001) and lower peripheral glucose uptake (glucose rate of disappearance, 6.9 ± 2.9 mg/kg/min for patients with T1D vs 11.3 ± 3.3 for controls; P < 0.0001) during hyperinsulinemia compared with controls. In youth with T1D, glucose rate of disappearance correlated with free fatty acid at the 80-mU/m2/min phase (P = 0.005), markers of inflammation (IL-6; P = 0.012), high-sensitivity C-reactive protein (P = 0.001), and leptin (P = 0.008)], but not hemoglobin A1c.

CONCLUSIONS

Adolescents with T1D have adipose, hepatic and peripheral IR. This IR occurs regardless of obesity and metabolic syndrome features. Youth with T1D may benefit from interventions directed at improving IR in these tissues, and this area requires further research.

NIRCa: An artificial neural network-based insulin resistance calculator

BACKGROUND

Direct measurement of insulin sensitivity in children with type 1 diabetes is cumbersome and time consuming.

OBJECTIVE

The aim of our study was to develop novel, accurate machine learning-based methods of insulin resistance estimation in children with type 1 diabetes.

METHODS

A hyperinsulinemic hyperglycemic clamp study was performed to evaluate the glucose disposal rate (GDR) in a study group consisting of 315 patients aged 7.6 to 19.7 years. The group was randomly divided into a training and independent testing set for model performance assessment. GDR was estimated on the basis of simple clinical variables using 2 non-linear methods: artificial neural networks (ANN) and multivariate adaptive regression splines (MARSplines). The results were compared against the most frequently used predictive model, based on waist circumference, triglyceride (TG), and HbA1c levels.

RESULTS

The reference model showed moderate performance ( R ² = 0.26) with a median absolute percentage error of 49.1%, and with the worst fit observed in young (7-12 years) children ( R ² = 0.17). Predictions of the MARSplines model were significantly more accurate than those of the reference model (median error 3.6%, R ² = 0.44 P < .0001). The predictions of the ANN, however, showed significantly lower error than those of the reference model (P < .0001) and MARSplines (P < .0001) and better fit regardless of patient age. ANN-estimated GDRs were within a ±20% error range in 75% of cases with a median error of 0.6% and an R ² = 0.66. The predictive tool is available at http://link.konsta.com.pl/gdr.

CONCLUSIONS

The developed GDR estimation model reliant on ANN allows for an optimized prediction of GDR for research and clinical purposes.

Modifiable Risk Factors for Cardiovascular Disease in Children with Type 1 Diabetes: Can Early Intervention Prevent Future Cardiovascular Events?

PURPOSE OF REVIEW

Patients with type 1 diabetes have increased risk for cardiovascular disease. The purpose of this review is to examine the following: i) current evidence for subclinical cardiovascular disease (CVD) in children with type 1 diabetes (T1DM) ii) known modifiable risk factors for CVD and their relationship to subclinical CVD in this population iii) studies that have addressed these risk factors in order to improve CVD outcomes in children with T1DM RECENT FINDINGS: Subclinical CVD presents in children as increased carotid intima-media thickness, increased arterial stiffness, and endothelial and myocardial dysfunction. Modifiable risk factors for CVD include hyperglycemia, hyperlipidemia, obesity, hypertension, depression, and autonomic dysfunction. Very few randomized controlled studies have been done in children with T1DM to examine how modification of these risk factors can affect their CVD. Children with T1DM have subclinical CVD and multiple modifiable risk factors for CVD. More research is needed to define how modification of these factors affects the progression of CVD.

Central Arterial Function Measured by Non-invasive Pulse Wave Analysis is Abnormal in Patients with Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder caused by mutation of dystrophin. Cardiovascular involvement includes dilated cardiomyopathy. Non-invasive assessment of vascular function has not been evaluated in DMD. We hypothesize arterial wave reflection is abnormal in patients with DMD. Pulse wave analysis was performed on DMD patients with a SphygmoCor SCOR-PVx System to determine central blood pressure and augmentation index (AIx) as an assessment of arterial wave reflection. Results were compared to a control group. A total of 43 patients with DMD were enrolled, and compared to 43 normal controls. Central systolic blood pressure was lower, while both AIx-75 (7.8 ± 9.6% vs. 2.1 ± 10.4%, p 0.01, DMD vs. normal) and AIx-not corrected (16.8 ± 10.1% vs. -3.6 ± 10.9, p < 0.001, DMD vs. normal) were higher in the DMD compared to control. Using multivariable linear regression model, the variables found to have a significant effect on AIx-not corrected included diagnosis of DMD, height, and heart rate (r ² = 0.257). The current data suggest that, despite lower central systolic blood pressure, patients with DMD have higher wave reflection when compared to normal controls, which may represent increased arterial stiffness. Overall there appears to be no effect on ventricular systolic function, however the long-term consequence in this group is unknown. Further study is required to determine the mechanism of these differences, which may be related to the effects of systemic steroids or the role of dystrophin in vascular function.

Evaluation of arterial stiffness in children with type 1 diabetes using the oscillometric method

AIMS

Pulse wave velocity (PWV) is an accepted evaluation method to assess vascular changes and determine cardiovascular disease risk in type 1 diabetes (T1D) patients. The aim of this study was to identify atherosclerosis risk by using oscillometric device in pediatric patients who had T1D but no end organ impairment and no cardiovascular disease findings.

MATERIALS AND METHODS

Pediatric patients with T1D and no determined end organ impairment and cardiovascular disease were involved in the study.

RESULTS

A total of 72 patients with T1D containing 32 males and 40 females were included in the study. A total of 77 patients including 39 males and 38 females were evaluated as healthy control group. The average age of patients with T1D was 12.8±3.7years, their average weight was established as 43.8±16.7kg. The average age of control group was 12.3±1.6years and average weight was determined as 46.8±12.8kg. When the results obtained by pulse wave method were compared; PWV and Alx_75 values in T1D patients (respectively, 4.63±0.40 and 22.9±6.7) were determined significantly higher than those of control group (respectively, 4.42±0.34 and 16.6±6.6). A positive correlation was identified between diabetes duration and HbA1c (instant and mean) levels in patients with T1D with respect to PWV and Alx_75 values.

CONCLUSIONS

Arterial stiffness was impaired in children with T1D with no end organ impairment using oscillometric method. This impairment was related to high HbA1c levels and diabetes duration.

Predictors of Increased Carotid Intima-Media Thickness in Youth With Type 1 Diabetes: The SEARCH CVD Study

OBJECTIVE

Youth with type 1 diabetes have worse cardiovascular (CV) risk factors and higher carotid intima-media thickness (IMT) than their peers without diabetes. Whether the burden of CV risk factors over time is associated with carotid IMT at follow-up in youth with type 1 diabetes is not known.

RESEARCH DESIGN AND METHODS

Two hundred ninety-eight youth with type 1 diabetes (mean age 13.3 ± 2.9 years, 87.6% non-Hispanic white, 53.7% male) had two study visits 5 years apart. CV risk factors, including BMI, lipids, blood pressure, hemoglobin A(1c), and smoking status, were assessed at both visits, and carotid IMT was measured at follow-up using B-mode ultrasonography. Linear regression models with an area under the curve measurement that incorporated the baseline and follow-up CV risk factors were used to evaluate the relationship with carotid IMT at follow-up.

RESULTS

All CV risk factors worsened significantly over time (except LDL cholesterol) (P < 0.05). From baseline to follow-up, the number of abnormal CV risk factors also increased (P < 0.05). Predictors of carotid IMT were older age, male sex, and higher BMI z score area under the curve (all P < 0.05).

CONCLUSIONS

The CV risk factor burden increases over time in youth with type 1 diabetes. BMI z score was the only modifiable CV risk factor that predicted carotid IMT. This study highlights the critical need to better understand the risk factors that influence carotid IMT early in the course of type 1 diabetes.

Early changes in cardiovascular structure and function in adolescents with type 1 diabetes

Background

Children with type 1 diabetes (T1D) are at higher risk of early adult-onset cardiovascular disease. We assessed cardiovascular structure and function in adolescents with T1D compared with healthy controls and the relationships between peripheral vascular function and myocardial parameters.

Methods and results

199 T1D [14.4 ± 1.6 years, diabetes duration 6.2 (2.0–12.8) years] and 178 controls (14.4 ± 2.1 years) completed endothelial function by flow mediated vasodilatation (FMD), arterial stiffness using pulse wave velocity (PWV) along with M-mode, pulse wave and tissue Doppler, and myocardial deformation echocardiographic imaging. Systolic (113 ± 10 vs. 110 ± 9 mmHg; p = 0.0005) and diastolic (62 ± 7 vs. 58 ± 7 mmHg; p < 0.0001) blood pressures, carotid femoral PWV and endothelial dysfunction measurements were increased in T1D compared with controls. Systolic and diastolic left ventricular dimensions and function by M-mode and pulse wave Doppler assessment were not significantly different. Mitral valve lateral e’ (17.6 ± 2.6 vs. 18.6 ± 2.6 cm/s; p < 0.001) and a’ (5.4 ± 1.1 vs. 5.9 ± 1.1 cm/s; p < 0.001) myocardial velocities were decreased and E/e’ (7.3 ± 1.2 vs. 6.7 ± 1.3; p = 0.0003) increased in T1D. Left ventricular mid circumferential strain (−20.4 ± 2.3 vs. −19.5 ± 1.7 %; p < 0.001) was higher, whereas global longitudinal strain was lower (−19.0 ± 1.9 vs. −19.8 ± 1.5 % p < 0.001) in T1D.

Conclusions

Adolescents with T1D exhibit early changes in blood pressure, peripheral vascular function and left ventricular myocardial deformation indices with a shift from longitudinal to circumferential shortening. Longitudinal follow-up of these changes in ongoing prospective trials may allow detection of those most at risk for cardiovascular abnormalities including hypertension that could preferentially benefit from early therapeutic interventions.