Structural and functional cardiac abnormalities in adolescent girls with poorly controlled type 2 diabetes

Cardiovascular and Respiratory Measures in Adults With Early-onset Type 2 Diabetes Mellitus Compared With Matched Controls

OBJECTIVES

The aim of the study was to compare cardiac and respiratory function at rest in participants with early-onset type 2 diabetes and a control group without diabetes, matched for age, sex, and body mass index (BMI).

METHODS

This study included 18 participants with early-onset type 2 diabetes (12 men and 6 women, age 34.9±6 years, diabetes duration 3.1±3.0 years) and 14 control participants without diabetes, matched for age, sex, and BMI (9 men and 5 women, age 32.9±5.2 years). Participants underwent resting echocardiography and pulmonary function tests. Fasting blood samples were analyzed for glycated hemoglobin, glucose, C-reactive protein, insulin, free fatty acids, and N-terminal pro-B-type natriuretic peptide.

RESULTS

Significant differences between groups were observed in left ventricular diastolic function at rest. Compared with controls, the group with early-onset type 2 diabetes had lower E/A (ratio between early [E] and late [A] ventricular filling velocity) (p=0.002), higher E/e' (representing left ventricular filling pressure) (p=0.017), lower e' (early myocardial relaxation velocity) (p<0.001), and lower diffusing capacity of the lung for carbon monoxide (p=0.003).

CONCLUSIONS

Subclinical left ventricular diastolic dysfunction and lower lung diffusing capacity were detected in participants with early-onset type 2 diabetes when compared with matched controls.

Subclinical impairment of left ventricular function assessed by speckle tracking in Type 2 diabetic obese and non-obese patients: Case control study

Objectives:

Materials and Methods:

Results:

Conclusion:

The effect of overweight/obesity on diastolic function in children and adolescents: A meta-analysis

Left ventricular diastolic function (LVDF) is an important marker of early cardiovascular remodelling, which has not been well summarized in young people with overweight/obesity. Weighted, random-effects regression was used to determine the strength of associations of both body mass index (BMI) and homeostatic model assessment of insulin resistance (HOMA-IR) with LVDF measures, adjusting for age and sex. Six databases were searched after PROSPERO registration (CRD42020177470) from inception to July 2020 for studies that compared LVDF between overweight/obesity and control groups aged ≤24 years, yielding 70 studies (9983 individuals). Quality and risk of bias were assessed using NHLBI tools, with scores of good, fair, and poor for 6, 48, and 16 studies, respectively. Increased BMI was associated with worse LVDF in all measures except early mitral inflow deceleration time, with septal early diastolic tissue peak velocity to late diastolic tissue peak velocity ratio having the strongest association (n = 13 studies, 1824 individuals; r = -0.69; P < 0.001). Elevated HOMA-IR was also associated with worse LVDF. Although we could not determine the causality of reduced LVDF in young people, our findings should aid the development of paediatric guidelines for the assessment of LVDF and support further work to address the longitudinal consequences of childhood obesity and IR on LVDF.

A cross sectional study to compare cardiac structure and diastolic function in adolescents and young adults with youth-onset type 1 and type 2 diabetes: The SEARCH for Diabetes in Youth Study

AIMS

To compare left ventricular structure (LV) and diastolic function in young adults with youth- onset diabetes by type, determine the prevalence of abnormal diastolic function by diabetes type using published values from age similar healthy controls, and examine the risk factors associated with diastolic function.

METHODS

In a cross sectional analysis we compared LV structure and diastolic function from two dimensional echocardiogram in participants with type 1 (T1D) and type 2 diabetes (T2D) who participated in the SEARCH for Diabetes in Youth Study. Linear models were used to examine the risk factors associated with worse diastolic function.

RESULTS

Of 479 participants studied, 258 had T1D (mean age 21.2 ± 5.2 years, 60.5% non-Hispanic white, 53.9% female) and 221 had T2D (mean age 24.8 ± 4.3 years, 24.4% non-Hispanic white, 73.8% female). Median diabetes duration was 11.6 years. Participants with T2D had greater LV mass index and worse diastolic function that persisted after adjustment for differences in risk factors compared with participants with T1D (all p < 0.05). Abnormal diastolic function, quantified using healthy controls, was pronounced in both groups but greater in those with T2D than T1D (T2D: 57.7% vs T1D: 47.2%, respectively), p < 0.05. Risk factors associated with worse diastolic function included older age at diabetes diagnosis, female sex, higher BP, heart rate and HbA1c and longer diabetes duration.

CONCLUSIONS

LV structure and diastolic function is worse in individuals with T2D compared to T1D. However, abnormal diastolic function in seen in both groups compared to published values from age similar healthy controls.

Rapid progression of type 2 diabetes and related complications in children and young people-A literature review

Type 2 diabetes (T2D) is suggested to progress faster in children and young people vs type 1 diabetes (T1D) in the same age group and T2D in adults. We reviewed the evidence base for this. A literature search was performed of PubMed-indexed publications between 2000 and 2018, for the terms "pediatric" and "T2D." Results were combined and filtered for those relating to "progression." Searches of abstract books from Latin American and Asian congresses were performed to include these populations. Pediatric populations were defined as <25 completed years of age. Of the articles and congress abstracts found, 30 were deemed relevant. Dividing the studies into categories based on how T2D progresses, we found the following: (a) yearly beta-cell function deterioration was shown to be 20% to 35% in children with T2D compared with 7% to 11% in adults with T2D, despite similar disease durations; (b) retinopathy progression was likely dependent on diabetes duration rather than diabetes type; however, nephropathy, neuropathy and probably hypertension progressed faster in youth-onset T2D vs T1D. Nephropathy progression was similar to adults with T2D, allowing for disease duration. Youth with T2D had a worse cardiovascular (CV) risk profile than youth with T1D, and a faster progression to CV death. (c) Progression to treatment failure was faster in youth-onset T2D vs adult-onset T2D. Substantial evidence exists for faster progression of T2D in pediatric patients vs T1D or adult-onset T2D. New treatments targeting the pathology are needed urgently to address this issue.

Heart Rate Variability and Cardiac Autonomic Dysfunction: Prevalence, Risk Factors, and Relationship to Arterial Stiffness in the Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) Study

OBJECTIVE

To determine whether prior type 2 diabetes (T2D) treatment or glycemic control over time are independently associated with heart rate variability (HRV) and whether the presence of cardiac autonomic dysfunction is associated with arterial stiffness in young adults with youth-onset T2D enrolled in the Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) study.

RESEARCH DESIGN AND METHODS

Heartbeats over 10 min were measured to derive the normal R-Rs (NN intervals). Outcomes included the standard deviation of the NN intervals (SDNN), the root mean square differences of successive NN intervals (RMSSD), percent of NN beats that differ by more than 50 ms (PNN50), and the low-frequency (LF) power domain, high-frequency (HF) power domain, and their ratio (LF:HF). Autonomic dysfunction was defined as ≥3 of 5 abnormal HRV indices compared with obese controls from a separate study.

RESULTS

A total of 397 TODAY participants were evaluated 7 years after randomization. TODAY participants had reduced HRV (SDNN 58.1 ± 29.6 ms vs. controls 67.1 ± 25.4 ms; P < 0.0001) with parasympathetic loss (RMSSD 53.2 ± 36.7 ms vs. controls 67.9 ± 35.2 ms; P < 0.0001) with sympathetic overdrive (LF:HF ratio 1.4 ± 1.7 vs. controls 1.0 ± 1.1; P < 0.0001). Cardiac autonomic dysfunction was present in 8% of TODAY participants, and these participants had greater pulse wave velocity compared with those without dysfunction (P = 0.0001). HRV did not differ by randomized treatment, but higher hemoglobin A1c (HbA_1c) over time was independently associated with lower SDNN and RMSSD and higher LF:HF ratio after adjustment for age, race-ethnicity, sex, and BMI.

CONCLUSIONS

Young adults with youth-onset T2D show evidence of cardiac autonomic dysfunction with both parasympathetic and sympathetic impairments that are associated with higher HbA_1c.

Abnormal Myocardial Dietary Fatty Acid Metabolism and Diabetic Cardiomyopathy

Patients with diabetes are at very high risk of hospitalization and death from heart failure. Increased prevalence of coronary heart disease, hypertension, autonomic neuropathy, and kidney failure all play a role in this increased risk. However, cardiac metabolic abnormalities are now recognized to play a role in this increased risk. Increased reliance on fatty acids to produce energy might predispose the diabetic heart to oxidative stress and ischemic damage. Intramyocellular accumulation of toxic lipid metabolites leads to a number of cellular abnormalities that might also contribute to cardiac remodelling and cardiac dysfunction. However, fatty acid availability from circulation and from intracellular lipid droplets to fuel the heart is critical to maintain its function. Fatty acids delivery to the heart is very complex and includes plasma nonesterified fatty acid flux as well as triglyceride-rich lipoprotein-mediated transport. Although many studies have shown a cross-sectional association between enhanced fatty acid delivery to the heart and reduction in left ventricular function in subjects with prediabetes and diabetes, these mechanisms change very rapidly during type 2 diabetes treatment. The present review focuses on the role of fatty acids in cardiac function, with particular emphasis on the possible role of early abnormalities of dietary fatty acid metabolism in the development of diabetic cardiomyopathy.

Cardiac Abnormalities in Youth with Obesity and Type 2 Diabetes

Childhood obesity has been linked to cardiovascular disease (CVD) risk in adulthood. Of great concern is the expected increase in the population's CVD burden in relation to childhood obesity. This is compounded by the risk related to chronic hyperglycemia exposure in youth with type 2 diabetes. We herein provide an overview of the spectrum of early cardiovascular disease manifestation in youth with obesity and type 2 diabetes, in particular abnormalities in cardiac structure and function. Cardiac remodeling and adverse target organ damage is already evident in the pediatric age group in children with obesity and type 2 diabetes. This supports the importance of intensifying obesity prevention efforts and early intervention to treat comorbidities of obesity in the pediatric age group to prevent cardiac events in early adulthood.

Cardiopulmonary Dysfunction and Adiponectin in Adolescents With Type 2 Diabetes

Background

Myocardial mechanics are altered in adults with obesity and type 2 diabetes (T2D); insulin resistance and adipokines have been implicated as important risk factors for cardiovascular disease, but these relationships are poorly described in adolescents. We hypothesized that obese adolescents and adolescents with T2D would have abnormal cardiac function compared to lean adolescents. In addition, we hypothesized that insulin sensitivity (IS), adiposity, and adipokines would be associated with altered cardiac strain and cardiopulmonary fitness in adolescents with T2D.

Methods and Results

Adolescents (15±2 years) with T2D (n=37), obesity without diabetes (n=41), and lean controls (n=31) of similar age and pubertal stage underwent echocardiography with speckle tracking, assessment of IS by hyperinsulinemic–euglycemic clamp, body composition by dual‐energy x‐ray absorptiometry, peak oxygen consumption (VO₂peak) by cycle ergometry, adiponectin, and leptin. Compared to lean and to obese controls, adolescents with T2D had significantly lower cardiac circumferential strain (CS) (−18.9±4.6 [T2D] versus −21.5±3.5 [obese] versus −22.0±4.2% [lean], P=0.04) and VO₂peak (37.6±7.5 [T2D] versus 43.4±8.2 [obese] versus 47.6±8.6 mL/lean kg/min [lean], P<0.0001). In T2D youth, VO₂peak was associated with CS, and the association remained significant after adjusting for age, sex, and IS (β±SE: −0.73±0.26, P=0.02). Among adolescents with T2D, CS was also associated with adiponectin, longitudinal strain with leptin, and VO₂peak with adiponectin and IS.

Conclusions

Adolescents with T2D had abnormal CS and reduced VO₂peak compared to obese and lean controls, which may represent the earliest evidence of cardiac functional impairment in T2D. Low adiponectin, rather than conventional risk factors and IS, correlated with CS, while both adiponectin and IS related to cardiopulmonary fitness.

Morbidity and mortality in young-onset type 2 diabetes in comparison to type 1 diabetes: where are we now?

Increasingly, we recognise that type 2 diabetes in youth is a disease with an aggressive time course and a significant complication risk. On the other hand, outcomes for youth with type 1 diabetes appear generally to be improving. With increasing numbers of both types of diabetes in youth, it is timely that a comparative perspective is offered to help clinicians prognosticate more appropriately. Contemporary comparative studies add a new perspective to a consistent story, that for youth-onset type 2 diabetes, the development and progression of cardio-renal complications are increased and the survival prognosis is significantly worse than for type 1 diabetes. Here, we review this mounting evidence, highlight the importance of metabolic syndrome factors in the excess risk and underscore that there remains a significant mortality gap for youth with either type of diabetes, to be addressed as a matter of urgency.

Subclinical impairment of left ventricular function in diabetic patients with or without obesity: A study based on three-dimensional speckle tracking echocardiography

AIMS

The aim of this study was to investigate subclinical left ventricular (LV) changes between type 2 diabetic patients with or without obesity using three-dimensional speckle-tracking echocardiography (3DSTE).

METHODS

A total of 77 type 2 diabetic patients, including 36 subjects with BMI < 25 kg/m(2) and 41 subjects with BMI ≥ 25 kg/m(2), as well as 40 age- and sex-matched controls (BMI: 18.5 ~ 24.5 kg/m(2)) were studied. Waist circumference was measured in diabetic patients with a BMI ≥ 25 kg/m(2) to determine whether abdominal obesity as a complication was present. Real-time three-dimensional (3D) full volume images of the left ventricle were recorded and analyzed. Left ventricular ejection fraction (LVEF), global longitudinal strain (GLS), global circumferential strain (GCS), global area strain (GAS), and global radial strain (GRS) were calculated and compared.

RESULTS

Compared with the controls, diabetic subjects without overall obesity had significantly lower GCS, GAS, and GRS (p < 0.05), as well as markedly lower GLS (p < 0.001). However, 3D-LVEF and all global strains in diabetic subjects with overall obesity were not only markedly lower compared with controls (p  <  0.002 and p < 0.001), but also significantly lower than those in diabetic subjects without overall obesity (p  <  0.002 and p  <  0.05). HbA1c and BMI showed negative impacts on all strains in diabetic patients. Meanwhile, the diabetic subjects with overall and abdominal obesity had significantly reduced GLS, GCS, GAS, and GRS compared with those with overall obesity only (all p  <  0.05).

CONCLUSIONS

Type 2 diabetic patients demonstrated early-stage subclinical LV deformation and dysfunction, whilst coexistent obesity resulted in further damage to myocardial contractility and reduced LVEF. 3DSTE was a sensitive method for detecting these abnormalities.

Cardiovascular complications of type 2 diabetes in youth

The prevalence of type 2 diabetes mellitus (T2DM) in youth has increased dramatically over the past decades. The literature also suggests that the progression from an impaired glucose tolerance state to established T2DM is more rapid in youth, compared to adults. The presence of significant cardiovascular complications in youth with T2DM, including cardiac, macrovascular, and microvascular remodeling, is another major issue in this younger cohort and poses a significant threat to the healthcare system. However, this issue is only now emerging as a major public health concern, with few data to support optimal treatment targets and strategies to reduce cardiovascular disease (CVD) risk in youth with T2DM. Accordingly, the purpose of this minireview is to better understand the cardiovascular complications in youth with T2DM. We briefly describe the pathophysiology from youth studies, including oxidative stress, inflammation, renin-angiotensin aldosterone system, and epigenetics, which link T2DM and CVD. We also describe the literature concerning the early signs of CVD in youth and potential treatment options to reduce cardiovascular risk.

Type 2 diabetes mellitus and obesity in young adults: the extreme phenotype with early cardiovascular dysfunction

AIM

A pilot study to phenotype young adults (< 40 years) with Type 2 diabetes mellitus.

METHODS

Twenty people with Type 2 diabetes (aged 18-40 years), 10 lean and 10 obese control subjects underwent detailed assessment, including tagged cardiac magnetic resonance imaging, inflammatory proteins, lipids, vitamin D and maximal oxygen uptake. Outcomes were compared between the group with Type 2 diabetes and the control group.

RESULTS

Mean (standard deviation) age, Type 2 diabetes duration and BMI in the group with Type 2 diabetes were 31.8 (6.6) years, 4.7 (4.0) years and 33.9 (5.8) kg/m(2) respectively. Compared with lean control subjects, those with Type 2 diabetes had more deleterious profiles of hyperlipidaemia, vitamin D deficiency, inflammation and maximal oxygen uptake relative to body mass. However, there was no difference between the group with Type 2 diabetes and the obese control group. The group with Type 2 diabetes had a higher left ventricular mass and a trend towards concentric remodelling compared with the lean control group (P = 0.002, P = 0.052) but not the obese control group (P > 0.05). Peak early diastolic strain rate was reduced in the group with Type 2 diabetes [1.51 (0.24)/s] compared with the lean control [1.97 (0.34)/s, P = 0.001] and obese control [1.78 (0.39)/s, P = 0.042] group.

CONCLUSIONS

Young adults with Type 2 diabetes and those with obesity have similar adverse cardiovascular risk profiles, higher left ventricular mass and a trend towards left ventricular concentric remodelling. In addition, those with Type 2 diabetes demonstrate diastolic dysfunction, a known risk marker for future heart failure and mortality.

Systolic and diastolic abnormalities reduce the cardiac response to exercise in adolescents with type 2 diabetes

OBJECTIVE

To better understand the cardiac limitations during exercise in adolescents with type 2 diabetes mellitus (T2DM), we measured left ventricular performance with magnetic resonance imaging (MRI) during exercise in diabetic and nondiabetic adolescents.

RESEARCH DESIGN AND METHODS

Thirteen subjects with T2DM, 27 overweight/obese nondiabetic (ObeseND) subjects, and 19 nondiabetic nonobese control subjects were recruited. Cardiac (left ventricular) MRI scans were performed at rest and during submaximal exercise.

RESULTS

Vo2 peak indexed to fat-free mass was reduced in T2DM and ObeseND subjects compared with control subjects (P < 0.0001). Indexed cardiac output increased less during exercise and was 20% lower in T2DM subjects due to reduced stroke volume. This was a consequence of reduced ventricular filling with smaller end-diastolic volume, which decreased further during exercise in T2DM subjects, but not in ObeseND or control subjects. End-systolic volume was also smaller in T2DM subjects. These changes were associated with increased resting and exercise diastolic blood pressure, and total peripheral resistance in T2DM subjects.

CONCLUSIONS

Independently of obesity, T2DM impairs cardiac function during exercise in adolescents.

Increased myocardial uptake of dietary fatty acids linked to cardiac dysfunction in glucose-intolerant humans

Impaired cardiac systolic and diastolic function has been observed in preclinical models and in subjects with type 2 diabetes. Using a recently validated positron emission tomography (PET) imaging method with 14(R,S)-[(¹⁸F]-fluoro-6-thia-heptadecanoic acid to quantify organ-specific dietary fatty acid partitioning, we demonstrate in this study that overweight and obese subjects with impaired glucose tolerance (IGT⁺) display significant increase in fractional myocardial dietary fatty acid uptake over the first 6 h postprandial compared with control individuals (IGT⁻). Measured by [¹¹C]acetate with PET, IGT⁺ subjects have a significant increase in myocardial oxidative index. IGT⁺ subjects have significantly reduced left ventricular stroke volume and ejection fraction (LVEF) and tend to display impaired diastolic function, as assessed by PET ventriculography. We demonstrate an inverse relationship between increased myocardial dietary fatty acid partitioning and LVEF. Fractional dietary fatty acid uptake is reduced in subcutaneous abdominal and visceral adipose tissues in IGT⁺ directly associated with central obesity. Fractional dietary fatty acid uptake in skeletal muscles or liver is, however, similar in IGT⁺ versus IGT⁻. The current study demonstrates, for the first time, that excessive myocardial partitioning of dietary fatty acids occurs in prediabetic individuals and is associated with early impairment of left ventricular function and increased myocardial oxidative metabolism.

Diastolic function is reduced in adolescents with type 1 diabetes in response to exercise

OBJECTIVE

To determine whether adolescents with type 1 diabetes have left ventricular functional changes at rest and during acute exercise and whether these changes are affected by metabolic control and diabetes duration.

RESEARCH DESIGN AND METHODS

The study evaluated 53 adolescents with type 1 diabetes and 22 control adolescents. Baseline data included peak exercise capacity and body composition by dual-energy X-ray absorptiometry. Left ventricular functional parameters were obtained at rest and during acute exercise using magnetic resonance imaging.

RESULTS

Compared with nondiabetic control subjects, adolescents with type 1 diabetes had lower exercise capacity (44.7 ± 09 vs. 48.5 ± 1.4 mL/kg fat-free mass [FFM]/min; P < 0.05). Stroke volume was reduced in the diabetes group at rest (1.86 ± 0.04 vs. 2.05 ± 0.07 mL/kg FFM; P = 0.02) and during acute exercise (1.89 ± 0.04 vs. 2.17 ± 0.06 mL/kg FFM; P = 0.01). Diabetic adolescents also had reduced end-diastolic volume at rest (2.94 ± 0.06 vs. 3.26 ± 0.09 mL/kg FFM; P = 0.01) and during acute exercise (2.78 ± 0.05 vs. 3.09 ± 0.08 mL/kg FFM; P = 0.01). End-systolic volume was lower in the diabetic group at rest (1.08 ± 0.03 vs. 1.21 ± 0.04 mL/kg FFM; P = 0.01) but not during acute exercise. Exercise capacity and resting and exercise stroke volumes were correlated with glycemic control but not with diabetes duration.

CONCLUSIONS

Adolescents with type 1 diabetes have reduced exercise capacity and display alterations in cardiac function compared with nondiabetic control subjects, associated with reduced stroke volume during exercise.

Exercise attenuates the premature cardiovascular aging effects of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2D) is an example of a disease process that results in decrements in function additional to those imposed by the inexorable 'primary aging' process. These decrements due to disease, rather than primary aging, can be termed 'secondary aging', and include the premature development (as early as adolescence) of asymptomatic preclinical cardiovascular abnormalities (e.g. endothelial dysfunction, arterial stiffness, diastolic dysfunction), as well as impaired exercise performance. These abnormalities are important, as they are associated with greater cardiovascular morbidity and mortality in people with and without T2D. A better understanding of the pathophysiology of secondary cardiovascular aging in people with T2D is warranted, and an evaluation of the benefits of existing treatments for these abnormalities is useful (e.g. exercise training). The focus of this review is to discuss the data relevant to the following key postulates: (a) T2D causes premature cardiovascular aging; (b) in contrast to primary cardiovascular aging, the premature cardiovascular aging of T2D may be modifiable with exercise. The exercise-focused perspective for this review is appropriate because impairments in exercise performance are markers of premature cardiovascular aging in T2D, and also because exercise training shows promise to attenuate some aspects of cardiovascular aging during the preclinical stage.

The effects of obesity and type 2 diabetes mellitus on cardiac structure and function in adolescents and young adults

AIMS/HYPOTHESIS

We sought to evaluate the effects of obesity and obesity-related type 2 diabetes mellitus on cardiac geometry (remodelling) and systolic and diastolic function in adolescents and young adults.

METHODS

Cardiac structure and function were compared by echocardiography in participants who were lean, obese or obese with type 2 diabetes (obese diabetic), in a cross sectional study. Group differences were assessed using ANOVA. Independent determinants of cardiac outcome measures were evaluated with general linear models.

RESULTS

Adolescents with obesity and obesity-related type 2 diabetes were found to have abnormal cardiac geometry compared with lean controls (16% and 20% vs <1%, p < 0.05). These two groups also had increased systolic function. Diastolic function decreased from the lean to obese to obese diabetic groups with the lowest diastolic function observed in the obese diabetic group (p < 0.05). Regression analysis showed that group, BMI z score (BMIz), group × BMIz interaction and systolic BP z score (BPz) were significant determinants of cardiac structure, while group, BMIz, systolic BPz, age and fasting glucose were significant determinants of the diastolic function (all p < 0.05).

CONCLUSIONS/INTERPRETATION

Adolescents with obesity and obesity-related type 2 diabetes demonstrate changes in cardiac geometry consistent with cardiac remodelling. These two groups also demonstrate decreased diastolic function compared with lean controls, with the greatest decrease observed in those with type 2 diabetes. Adults with diastolic dysfunction are known to be at increased risk of progressing to heart failure. Therefore, our findings suggest that adolescents with obesity-related type 2 diabetes may be at increased risk of progressing to early heart failure compared with their obese and lean counterparts.

An observational study of type 2 diabetes within a large Australian tertiary hospital pediatric diabetes service

BACKGROUND

Type 2 diabetes mellitus (T2DM) is emerging as a significant clinical problem within the pediatric population.

OBJECTIVE

The objective of this study was to identify patients with T2DM in a large tertiary hospital diabetes service and examine aspects relating to clinical course and management.

METHODS

An initial audit of our diabetes service (over 6 yr) was followed by a 2-yr period of prospective case ascertainment to identify patients with T2DM. Comprehensive data collection was then undertaken in these individuals.

RESULTS

Within our service (n = 1574), 33 young people with T2DM were identified. Significant levels of co-morbidity were evident - dyslipidaemia (56%), microalbuminuria (45%), hypertension (30%) and abnormal retinal findings (25%). Hypertension was more likely in those with greater initial and follow-up body mass index (BMI) [mean (SD) BMI: 36.3 (5.0) vs. 28.0 (6.3) kg/m(2) , p = 0.001, and 36.8 (5.3) vs. 28.5 (7.8) kg/m(2) , p = 0.007, respectively] and BMI standard deviation score (SDS) [mean (SD) BMI SDS: 2.34 (0.30) vs. 1.72 (0.66), p = 0.001, and 2.26 (0.31) vs. 1.38 (0.87), p < 0.001, respectively], whereas abnormal retinal findings were seen in those with higher HbA1c values at last appointment [geometric mean (range) 10.9 (8.4-13.6) vs. 7.4 (5.6-12.5)%, p = 0.01) and those with greater increases in HbA1c over time (+4.1 (3.1) vs. +0.2 (1.9)%, p = 0.009). Of the 33,9 (27%) were lost to follow-up.

CONCLUSIONS

At present, T2DM in youth remains a low burden on our services. Patients with this diagnosis, however, have significant problems that present a major challenge to the development of effective management strategies.

Abnormal in vivo myocardial energy substrate uptake in diet-induced type 2 diabetic cardiomyopathy in rats

The purpose of this study was to determine in vivo myocardial energy metabolism and function in a nutritional model of type 2 diabetes. Wistar rats rendered insulin-resistant and mildly hyperglycemic, hyperinsulinemic, and hypertriglyceridemic with a high-fructose/high-fat diet over a 6-wk period with injection of a small dose of streptozotocin (HFHFS) and control rats were studied using micro-PET (microPET) without or with a euglycemic hyperinsulinemic clamp. During glucose clamp, myocardial metabolic rate of glucose measured with [(18)F]fluorodeoxyglucose ([(18)F]FDG) was reduced by approximately 81% (P < 0.05), whereas myocardial plasma nonesterified fatty acid (NEFA) uptake as determined by [(18)F]fluorothia-6-heptadecanoic acid ([(18)F]FTHA) was not significantly changed in HFHFS vs. control rats. Myocardial oxidative metabolism as assessed by [(11)C]acetate and myocardial perfusion index as assessed by [(13)N]ammonia were similar in both groups, whereas left ventricular ejection fraction as assessed by microPET was reduced by 26% in HFHFS rats (P < 0.05). Without glucose clamp, NEFA uptake was approximately 40% lower in HFHFS rats (P < 0.05). However, myocardial uptake of [(18)F]FTHA administered by gastric gavage was significantly higher in HFHFS rats (P < 0.05). These abnormalities were associated with reduced Glut4 mRNA expression and increased Cd36 mRNA expression and mitochondrial carnitine palmitoyltransferase 1 activity (P < 0.05). HFHFS rats display type 2 diabetes complicated by left ventricular contractile dysfunction with profound reduction in myocardial glucose utilization, activation of fatty acid metabolic pathways, and preserved myocardial oxidative metabolism, suggesting reduced myocardial metabolic efficiency. In this model, increased myocardial fatty acid exposure likely occurs from circulating triglyceride, but not from circulating plasma NEFA.

Update on nonautoimmune diabetes in children

Over the last two decades, nonautoimmune-mediated type 2 diabetes mellitus (T2DM) has become a clinical entity of increasing importance among adolescents. Yet, research specific to adolescent T2DM is in its infancy. Our understanding of the epidemiology of T2DM among adolescents is complicated by variability in definition, incomplete knowledge of novel autoimmune epitopes, the presence of individuals with phenotypic overlap between type 1 and type 2 diabetes, and inadequate understanding of the contribution of common single-gene defects. Furthermore, a higher ratio of diagnosed to undiagnosed cases and a strong relationship with the onset of puberty suggest unique aspects of the pathophysiology in adolescents. Investigators have begun to address these areas while also identifying important relationships with the intrauterine development. Well-designed clinical studies are currently examining the adolescent-specific challenges in prevention and treatment of T2DM, whereas a number of associations struggle to provide screening and treatment guidelines to practitioners based on limited understanding of the phenomenon. Finally, there is growing understanding of medium- and long-term morbidity and mortality in early adulthood. Given the likelihood that early-onset T2DM will have important implications for future public health, continued attention to all aspects of this complex social, economic, and physiological disorder is critical.