Arterial stiffness, lipoprotein particle size, and lipoprotein particle concentration in children with type 1 diabetes

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

Clinical Trials.gov, NCT02821104.

Association of particles of lipoprotein subclasses with arterial stiffness in a high-risk working population: the Baptist Employee Healthy Heart Study (BEHHS)

Background

Arterial stiffness is an independent predictor of cardiovascular disease (CVD) morbidity and mortality. A risk factor-independent association of arterial stiffness with traditional lipids has been described extensively, but it is still unclear whether an independent relationship exists between arterial stiffness and particles of lipoprotein subclasses.

Methods

The Baptist Employee Healthy Heart Study (BEHHS) is a lifestyle intervention study examining the effects of web-based programs on reducing CVD risk in high-risk persons. Participants had their brachial arterial augmentation index (AI, a measure arterial stiffness) assessed using the EndoPAT 2000 device. Cardio IQ™ ion mobility lipoprotein fractionation was utilized for measurement of particles of lipoprotein subclasses.

Results

The population consisted of 182 participants, (74% women, 49% Hispanic) with a mean age of 52 ± 9 years. There was a significant trend association between quartiles of AI and total cholesterol, HDL-c, large LDL-p, small IDL-p, large IDL-p, and all subclasses of HDL particles (total HDL-p, small HDL-p, and large HDL-p). In logistic regression analysis, only HDL-c, total LDL-p, large LDL-p, small IDL-p, large IDL-p, total HDL-p, small HDL-p, and large HDL-p demonstrated significant independent association with AI.

Conclusion

Several lipoprotein subclasses demonstrate independent significant associations with arterial stiffness. A safe and relatively inexpensive blood test may be useful in identifying subclinical atherosclerosis process in a relatively young high CVD risk population.

Trial registration

ClinicalTrials.gov, NCT01912209. Registered July 31, 2013

Specific Nuclear Magnetic Resonance Lipoprotein Subclass Profiles and Central Arterial Stiffness in Type 1 Diabetes Mellitus: A Case Control Study

BACKGROUND

Dyslipidemia has been associated with vascular complications of type 1 diabetes mellitus (T1DM). We examined the proton nuclear magnetic resonance (NMR)-assessed lipoprotein subclass profiles in subjects with T1DM compared with those of healthy subjects and assessed the potential relationship of these profiles with arterial stiffness.

METHODS

Eighty-four participants with T1DM of at least 10 years duration and no clinical cardiovascular disease (age: 35-65 years; 50% men) and 42 healthy participants were evaluated for: (1) clinical and anthropometric data (including classical cardiovascular risk factors), (2) insulin sensitivity by estimated glucose disposal rate, (3) microvascular complications, (4) NMR-assessed lipoprotein subclass profile, and (5) arterial stiffness (aortic pulse wave velocity).

RESULTS

Participants with T1DM had an apparently better conventional lipid profile than healthy participants, but with significant differences in NMR-assessed lipoprotein profiles such as higher triglyceride content of low-density lipoprotein (LDL) and high-density lipoprotein (HDL). In healthy participants, arterial stiffness was associated with NMR-based LDL subclasses. By contrast, in T1DM participants, arterial stiffness was independently associated mainly with NMR-based very-low-density lipoprotein (VLDL) subclasses: positively with total VLDL particles (and subclasses) and VLDL triglyceride content, and negatively with LDL and HDL particle sizes. These results were maintained after adjustments for classical cardiovascular risk factors.

CONCLUSIONS

Subjects with T1DM, while having an apparently better conventional lipid profile than healthy controls, presented significant alterations in their NMR-assessed lipoprotein profile. The association between arterial stiffness and NMR-assessed lipoprotein profiles also differed in both groups. These results support a potential role of the identified differences in the residual cardiovascular risk in T1DM.

Premeal insulin decreases arterial stiffness in children with type 1 diabetes

OBJECTIVE

To determine the effects of omitting meal time insulin on arterial stiffness in children with type 1 diabetes.

RESEARCH DESIGN AND METHODS

In this prospective, randomized, crossover study, radial artery tonometry and augmentation index adjusted to heart rate 75 (AI₇₅ ) were used to measure arterial stiffness. Children were randomized to receive or omit premeal insulin and completed the crossover portion of the study on a subsequent day. AI₇₅ was determined when fasting, 1, and 2 h postmeal.

RESULTS

When comparing change in AI₇₅ from baseline to 1 h and baseline to 2 h, when subjects received premeal insulin vs. no insulin, AI₇₅ was 4.5 units lower at 1 h (p = 0.011, 95% CI:1.1 lower to 8 lower) and 4.3 units lower at 2 h (p = 0.062, 95% CI: 0.2 higher to 8.9 lower) (n = 40).

CONCLUSIONS

Arterial stiffness is decreased by premeal insulin in children with type 1 diabetes.

HbA1c but not diabetes duration predicts increased arterial stiffness in adolescents with poorly controlled type 1 diabetes

BACKGROUND

The prevalence of macrovascular complications is probably underestimated in children with type 1 diabetes (T1D). Arterial stiffness (AS) is a subclinical marker of cardiovascular (CV) risk. The most validated, non-invasive method for AS measurement is pulse wave velocity (PWV). Only a few PWV studies have been performed in children with T1D.

OBJECTIVE

To explore the risk factors associated with AS in adolescents with suboptimally controlled T1D.

PATIENTS AND METHODS

Seventy-seven adolescents with T1D were included (39 girls, 38 boys) in this study. The adolescents had a median age of 16 yr (IQR 14-17), median duration of T1D was 9 yr (IQR 6-16), and HbA1c 71 mmol/mol (median, IQR 62-81). PWV was measured as the carotid-femoral pulse transmission time and converted into standard deviation scores (SDS) (adjusted for gender and age) using normative values for children. The risk factors assessed were HbA1c, T1D duration, treatment modality, serum lipids, and blood pressure (BP) measured via ambulatory blood pressure monitoring (ABPM).

RESULTS

The PWV did not differ from the reference data (median PWV was 5.1 m/s, i.e., -0.01 SDS). A significant positive association was observed between PWV-SDS and HbA1c (p = 0.001), total cholesterol (p = 0.003), LDL-cholesterol (p = 0.003), but not T1D duration (p = 0.78) according to the univariate analyses. In the multivariate model, the only significant variable that remained positively associated with PWV-SDS was HbA1c (p = 0.03).

CONCLUSIONS

Most adolescents with suboptimally controlled T1D have normal mean PWV compared to a healthy reference population. Chronic hyperglycemia, not T1D duration, is the main predictor of AS in adolescents.

Superiority of lipoprotein particle number to detect associations with arterial thickness and stiffness in obese youth with and without prediabetes

BACKGROUND

The nuclear magnetic resonance (NMR) lipoprotein profile provides additional cardiovascular risk information beyond traditional lipids in high-risk adults. Similar studies have not been conducted in youth.

OBJECTIVE

To evaluate the relationship between the NMR profile and preclinical vascular measures in youth.

METHODS

We studied 96 obese youth with prediabetes (mean age = 18.1 ± 3.6 years, 63% female, 78% African American) and 118 obese normoglycemic controls (mean age = 18.0 ± 3.1 years, 75% female, 62% African American) cross sectionally. Traditional lipids (triglycerides, total, high-density lipoprotein [HDL], and low-density lipoprotein [LDL] cholesterol), NMR particle size (particle concentration [P] and size) and vascular thickness (carotid IMT) and stiffness (pulse wave velocity [PWV]) were measured. Independent associations between lipoproteins with carotid IMT and PWV after adjustment for group, age, race, sex, BMI z score, blood pressure, HOMA-IR, and A1c were studied.

RESULTS

NMR analysis revealed youth with prediabetes exhibited a more atherogenic profile with higher levels of small LDL-P and HDL-P and lower levels of intermediate and large HDL-P (P < .03). In addition, lower intermediate HDL-P was associated with a higher carotid IMT, whereas higher small HDL-P was associated with a higher PWV (P < .01). Traditional lipids were not significantly different between groups and were not associated with either vascular outcome.

CONCLUSIONS

NMR lipoprotein subclasses have improved sensitivity compared to traditional lipids to detect lipoprotein abnormalities in normoglycemic and prediabetic obese youth and are independently associated with preclinical vascular thickness and stiffness. NMR lipids may enhance cardiovascular risk assessment in youth.

Glycemic control and high-density lipoprotein characteristics in adolescents with type 1 diabetes

BACKGROUND

Recent evidence suggests that high-density lipoprotein (HDL) physicochemical characteristics and functional capacity may be more important that HDL-C levels in predicting coronary heart disease. There is little data regarding HDL subclasses distribution in youth with type 1 diabetes.

OBJECTIVE

To assess the relationships between glycemic control and HDL subclasses distribution, composition, and function in adolescents with type 1 diabetes.

METHODS

This cross-sectional study included 52 adolescents with type 1 diabetes aged 12-16 years and 43 age-matched non-diabetic controls. Patients were divided into two groups: one in fair control [hemoglobin A1c (HbA1c) < 9.6%] and the second group with poor glycemic control (HbA1c ≥ 9.6%). In all participants, we determined HDL subclasses distribution, composition, and the ability of plasma and of isolated HDL to promote cellular cholesterol efflux. Levels of soluble adhesion molecules were also measured.

RESULTS

Although both groups of patients and the control group had similar HDL-C levels, linear regression analyses showed that compared with non-diabetic subjects, the poor control group had a lower proportion of HDL2b subclass (p = 0.029), triglyceride enriched (p = 0.045), and cholesteryl ester depleted (p = 0.028) HDL particles. Despite these HDL changes, cholesterol efflux was comparable among the three groups. The poor control group also had significantly higher intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 plasma concentrations.

CONCLUSIONS

In adolescents with type 1 diabetes, poor glycemic control is associated with abnormalities in HDL subclasses distribution and HDL lipid composition, however, in spite of these HDL changes, the ability of HDL to promote cholesterol efflux remains comparable to that of healthy subjects.

Cardiovascular disease risk in young people with type 1 diabetes

Cardiovascular disease (CVD) is the most frequent cause of death in people with type 1 diabetes (T1D), despite modern advances in glycemic control and CVD risk factor modification. CVD risk identification is essential in this high-risk population, yet remains poorly understood. This review discusses the risk factors for CVD in young people with T1D, including hyperglycemia, traditional CVD risk factors (dyslipidemia, smoking, physical activity, hypertension), as well as novel risk factors such as insulin resistance, inflammation, and hypoglycemia. We present evidence that adverse changes in cardiovascular function, arterial compliance, and atherosclerosis are present even during adolescence in people with T1D, highlighting the need for earlier intervention. The methods for investigating cardiovascular risk are discussed and reviewed. Finally, we discuss the observational studies and clinical trials which have thus far attempted to elucidate the best targets for early intervention in order to reduce the burden of CVD in people with T1D.

Cardiovascular function/dysfunction in adolescents with type 1 diabetes

Type 1 diabetes mellitus (T1D) is associated with an increased risk of cardiovascular disease (CVD) that begins in childhood. Youth with T1D develop concerning functional cardiac and vascular defects and evidence of early atherosclerosis, despite modern advancements in risk reduction and glycemic management. Such early defects predict poor long-term outcomes. Women with T1D also have higher CVD risk than expected for unexplained reasons. Insulin resistance (IR) is recently recognized as a prominent factor in T1D youth and adults, but with an atypical clinical phenotype. This IR may contribute to early cardiac and vascular dysfunction and long-term CVD in T1D. A better understanding of potential contributors to cardiovascular dysfunction in T1D youth such as IR and its unique phenotype in T1D, subtle lipid abnormalities, and gender differences is now required to address the current knowledge gaps and to prevent cardiovascular morbidity and mortality in T1D.