Prediabetes in obese youth: a syndrome of impaired glucose tolerance, severe insulin resistance, and altered myocellular and abdominal fat partitioning

Stabilization and reversal of child obesity in Andalusia using objective anthropometric measures by socioeconomic status

BACKGROUND

Childhood obesity continues to be a significant public health issue worldwide. Recent national studies in Spain show a stable picture. However, prevalence and trends differ by socio-economic status, age, and region. We present the trend in childhood excess weight prevalence, aged 8-15 years, in Andalusia from 2011-2012 to 2015-2016 by socio-economic status.

METHODS

Using the cross-sectional Andalusian Health Surveys, objective anthropometric measures were taken for a representative sample of 8-15 year olds in Andalusia in 2011-2012 and 2015-2016. Prevalence and changes in prevalence of excess weight (overweight plus obesity) were calculated, using both the WHO and IOTF criteria, overall and for sex, age and three different indicators of SES.

RESULTS

Overall prevalence of excess weight decreased from 42.0% in 2011-2012 to 35.4% in 2015-2016. Overweight decreased from 28.2 to 24.2% and obesity from 13.8 to 11.2%. In 2011-2012 the prevalence of excess weight in boys was 46.0%and 37.9% in girls; in 2015-2016 the difference became significant with 41% of boys with excess weight compared with 30% in girls.

CONCLUSIONS

Childhood excess weight prevalence in Andalusia has decreased slightly between 2011-2012 and 2015-2016. Notably, a decrease in obesity prevalence in girls aged 8-15 years was recorded. In 2011-2012 a social gradient for excess weight prevalence across three SES indicators was observed: in 2015-2016 this gradient disappeared. Nonetheless, prevalence remains too high.

Trajectories of changes in glucose tolerance in a multiethnic cohort of obese youths: an observational prospective analysis

BACKGROUND

Type 2 diabetes is preceded by a prediabetic stage of impaired glucose tolerance that affects 10-23% of youth and is expected to double over the next decade. The natural history of impaired glucose tolerance and the determinants of β-cell dynamic response have never been investigated longitudinally in young people. We aimed to investigate the clinical and metabolic determinants of longitudinal glucose tolerance changes and β-cell function in a multiethnic cohort of obese youth.

METHODS

We followed up prospectively a multiethnic cohort of overweight and obese (body-mass index >85th percentile) adolescents with baseline normal glucose tolerance (plasma glucose <140 mg/dL) or impaired glucose tolerance (plasma glucose 140-199 mg/dL) at the Yale Pediatric Obesity Clinic (CT, USA). All participants underwent a 3-h oral glucose tolerance test at baseline and after 2 years to estimate insulin secretion (oral disposition index) in the context of body insulin sensitivity. As part of standard care at the clinic, all participants received dietary advice and underwent dietary assessment every 5-6 months. No structured lifestyle or pharmacological intervention was administered.

FINDINGS

Between January, 2010, and December, 2016, 526 adolescents (mean age 12·7 years, range 10·6-14·2) were enrolled to our study. At baseline, 364 had normal and 162 had impaired glucose tolerance. Median follow-up was 2·9 years (IQR 2·7-3·1). 105 (65%) of 162 with impaired glucose tolerance at baseline reverted to normal glucose tolerance at follow-up, 44 (27%) had persistent impaired glucose tolerance, and 13 (8%) progressed to type 2 diabetes. A feature of reversion to normal glucose tolerance was a roughly four-fold increase in the oral disposition index (from median 0·94 [IQR 0·68-1·35] at baseline to 3·90 [2·58-6·08] at follow-up; p<0·0001) and a significantly higher oral disposition index at follow-up compared with participants who maintained normal glucose tolerance across the study period (median 3·90 [IQR 2·58-6·08] vs 1·59 [1·12-2·23]; p<0·0001). By contrast, a decrease in insulin secretion was seen in participants who had persistent impaired glucose tolerance (median 1·31 [IQR 1·01-1·85]; p<0·0001) or who progressed to type 2 diabetes (0·20 [0·12-0·58]; p<0·0001), compared with participants who maintained normal glucose tolerance across the study period. Non-Hispanic white ethnic origin conferred five times the odds of reversion to normal glucose tolerance compared with non-Hispanic black ethnic origin (OR 5·06, 95% CI 1·86-13·76; p=0·001), with a two times greater annual increase in the oral disposition index (β 2·32, 95% CI 0·05-4·60; p=0·045).

INTERPRETATION

Impaired glucose tolerance is highly reversible in obese adolescents. Ethnic origin is the main clinical modifier of the dynamic β-cell response to prediabetic hyperglycaemia and, thus, determines the reversibility of impaired glucose tolerance, or its persistence. Therapeutic interventions for impaired glucose tolerance should target the specific mechanisms underpinning glucose tolerance changes in high-risk ethnic groups.

FUNDING

National Institutes of Health (National Institute of Child Health and Human Development, National Center for Research Resources, and National Institute of Diabetes and Digestive and Kidney Diseases), American Diabetes Association, International Society for Pediatric and Adolescent Diabetes, Robert Leet Patterson and Clara Guthrie Patterson Trust, European Society for Pediatric Endocrinology, American Heart Association, and the Allen Foundation.

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.

Hypertriglyceridemia in Obese Children and Adolescents

The increasing prevalence of obesity in children and adolescents is a serious public health concern. Hypertriglyceridemia is common in obese children and adolescents, and elevated triglyceride (TG) level is a known biomarker of cardiometabolic risk. Results from genetic studies suggest that TG and TG-rich lipoproteins and, more specifically, remnant cholesterol are in the causal pathway of cardiovascular disease. However, simultaneous measurement of all remnants has not yet been established, and plasma TG level can be used as a useful marker of remnant cholesterol. Adipose tissue dysfunction, including impaired adipocyte TG storage and release of fatty acids, mediates the development of obesity-related complications. The prevalence of hypertriglyceridemia increases in overweight or obese children and is associated with other cardiometabolic risk factors. Recently, the TG/high-density lipoprotein cholesterol (HDL-C) ratio was recognized as a marker of structural vascular changes and insulin resistance in obese youth. Recent guidelines recommend universal lipid screening with nonfasting non-HDL-C measurement in children at 9–11 years of age; however, fasting lipid profiles should be measured in obese children and overweight adolescents and in those with high non-HDL-C in universal screening. The primary approach to lower TG in children includes dietary and lifestyle modifications; however, children with severe hypertriglyceridemia should also be referred to a pediatric lipid specialist.

Oxidative Stress, Intrauterine Growth Restriction, and Developmental Programming of Type 2 Diabetes

Intrauterine growth restriction (IUGR) leads to reduced birth weight and the development of metabolic diseases such as Type 2 diabetes in adulthood. Mitochondria dysfunction and oxidative stress are commonly found in key tissues (pancreatic islets, liver, and skeletal muscle) of IUGR individuals. In this review, we explore the role of oxidative stress in IUGR-associated diabetes etiology.

Descriptive epidemiology of metabolic syndrome among obese adolescent population

AIMS

The study was done to assess the magnitude of problems of metabolic syndrome among obese adolescents.

MATERIALS AND METHOD

It was a cross-sectional study done from January 2013 to June 2014 in paediatric endocrine outpatient department in BIRDEM General Hospital, Dhaka, Bangladesh. Total 172 adolescents having exogenous obesity aged 10-18 years were included. Impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and type 2 diabetes mellitus (DM) were defined as per WHO criteria.The adolescents having Body Mass Index (BMI) ≥95th centile were classified as obese.Waist circumference was measured at the level midway between the lower rib margin & the iliac crest, at the level of umbilicus with the person breathing out gently in centimeter. Hip circumference was measured at the maximum width over the buttocks at the level of the greater trochanters in centimeter.

RESULT

Among 172 obese adolescents, metabolic syndrome was found in 66 patients (38.4%). The commonest metabolic abnormality among those having metabolic syndrome was low HDL level (77.3%) followed by high triglyceride level(71.2%). Glucose intolerance (IFG and/or IGT) was found in 16.7%, Type 2 DM in 10.6%, systolic hypertension in 10.7% and diastolic hypertension in 12.1%. Triglyceride (p = 0.042) and Cholesterol level (p = 0.016) were significantly higher and HDL-cholesterol level (p = 0.000) was significantly lower among obese adolescents having metabolic syndrome. Less physical activity (p = 0.04) was significantly related to the development of metabolic syndrome. On logistic regression analysis male sex, family history of obesity and low HDL-cholesterol correlated to metabolic syndrome.

CONCLUSION

The High rate of metabolic syndrome among obese adolescents is alarming.

The effect of impaired glucose metabolism on weight loss in multidisciplinary childhood obesity treatment

OBJECTIVE

To investigate whether children and adolescents exhibiting an impaired glucose metabolism are more obese at treatment entry and less likely to reduce their degree of obesity during treatment.

METHODS

The present study is a longitudinal observational study, including children and adolescents from the Children's Obesity Clinic, Holbaek, Denmark. Anthropometrics, pubertal development, socioeconomic status (SES), and fasting concentrations of plasma glucose, serum insulin, serum C-peptide, and whole blood glycosylated hemoglobin (HbA1c) were collected at treatment entry and at follow-up. Proxies of Homeostasis Model Assessment 2-insulin sensitivity (HOMA2-IS) and Homeostasis Model Assessment 2-β-cell function (HOMA2-B) were calculated with the Homeostasis Model Assessment 2 program.

RESULTS

In total, 569 (333 boys) patients, median 11.5 years of age (range 6-22 years), and median body mass index (BMI) z-score 2.94 (range 1.34-5.54) were included. The mean BMI z-score reduction was 0.31 (±0.46) after 13 months (range 6-18) of treatment. At treatment entry, patients with impaired estimates of glucose metabolism were more obese than normoglycemic patients. Baseline concentration of C-peptide was associated with a lower weight loss during treatment in girls (P = .02). Reduction in the insulin concentrations was associated with reduction in BMI z-score in both sexes (P < .0001, P = .0005). During treatment, values of glucose, HbA1c, HOMA2-IS, and HOMA2-B did not change or impact the treatment outcome, regardless of age, sex, SES, or degree of obesity at treatment entry.

CONCLUSION

The capability to reduce weight during multidisciplinary treatment in children and adolescents with overweight/obesity is not influenced by an impaired glucose metabolism at study entry or during the course of treatment.

Impaired fasting glucose and the metabolic profile in Danish children and adolescents with normal weight, overweight, or obesity

OBJECTIVE

Whether the definitions of impaired fasting glucose (IFG) from the American Diabetes Association (ADA) and the World Health Organization (WHO) differentially impact estimates of the metabolic profile and IFG-related comorbidities in Danish children and adolescents is unknown.

METHODS

Two thousand one hundred and fifty four (979 boys) children and adolescents with overweight or obesity (median age 12 years) and 1824 (728 boys) children with normal weight (median age 12 years) from The Danish Childhood Obesity Biobank were studied. Anthropometrics, blood pressure, puberty, and fasting concentrations of glucose, insulin, glycosylated hemoglobin (HbA1c), and lipids were measured.

RESULTS

About 14.1% of participants with overweight or obesity exhibited IFG according to the ADA and 3.5% according to the WHO definition. Among individuals with normal weight, the corresponding prevalences were 4.3% and 0.3%. IFG was associated with a higher systolic blood pressure, higher concentrations of HbA1c, insulin, C-peptide (P < .0001) and triglycerides (P = .03), and lower HOMA2-IS and HOMA2-B (P < .0001) independent of sex, age, puberty, waist-to-height ratio, and degree of obesity. Furthermore, IFG was associated with a higher risk for hypertension (OR = 1.66 [95%CI: 1.21; 2.28], P = .002) and dyslipidemia (OR = 1.90 [95%CI: 1.38; 2.56], P < .0001) compared with the group without IFG independent of age, sex, and puberty.

CONCLUSIONS

The prevalence of IFG, when applying the ADA criterion compared with the WHO criterion, was 4 times higher in individuals with overweight and obesity and 14 times higher in individuals with normal weight in this study sample of children and adolescents. IFG was associated with a higher risk of hypertension and dyslipidemia compared with their normoglycemic peers regardless of the definition applied.

Parental and Child Factors Associated with Under-Estimation of Children with Excess Weight in Spain

Objective Understanding obesity misperception and associated factors can improve strategies to increase obesity identification and intervention. We investigate underestimation of child excess weight with a broader perspective, incorporating perceptions, views, and psychosocial aspects associated with obesity. Methods This study used cross-sectional data from the Spanish National Health Survey in 2011-2012 for children aged 2-14 years who are overweight or obese. Percentages of parental misperceived excess weight were calculated. Crude and adjusted analyses were performed for both child and parental factors analyzing associations with underestimation. Results Two-five year olds have the highest prevalence of misperceived overweight or obesity around 90%. In the 10-14 year old age group approximately 63% of overweight teens were misperceived as normal weight and 35.7 and 40% of obese males and females. Child gender did not affect underestimation, whereas a younger age did. Aspects of child social and mental health were associated with under-estimation, as was short sleep duration. Exercise, weekend TV and videogames, and food habits had no effect on underestimation. Fathers were more likely to misperceive their child´s weight status; however parent's age had no effect. Smokers and parents with excess weight were less likely to misperceive their child´s weight status. Parents being on a diet also decreased odds of underestimation. Conclusions for practice This study identifies some characteristics of both parents and children which are associated with under-estimation of child excess weight. These characteristics can be used for consideration in primary care, prevention strategies and for further research.

The extracellular domain of Staphylococcus aureus LtaS binds insulin and induces insulin resistance during infection

Insulin resistance is a risk factor for obesity and diabetes and predisposes individuals to Staphylococcus aureus colonization; however, the contribution of S. aureus to insulin resistance remains unclear. Here, we show that S. aureus infection causes impaired glucose tolerance via secretion of an insulin-binding protein extracellular domain of LtaS, eLtaS, which blocks insulin-mediated glucose uptake. Notably, eLtaS transgenic mice (eLtaS ^trans ) exhibited a metabolic syndrome similar to that observed in patients, including increased food and water consumption, impaired glucose tolerance and decreased hepatic glycogen synthesis. Furthermore, transgenic mice showed significant metabolic differences compared to their wild-type counterparts, particularly for the early insulin resistance marker α-hydroxybutyrate. We subsequently developed a full human monoclonal antibody against eLtaS that blocked the interaction between eLtaS and insulin, which effectively restored glucose tolerance in eLtaS ^trans and S. aureus-challenged mice. Thus, our results reveal a mechanism for S. aureus-induced insulin resistance.

The "adipose tissue expandability" hypothesis: a potential mechanism for insulin resistance in obese youth

Obesity has become a major global health challenge of the 21st century, as it is associated with the onset of type 2 diabetes (T2D) and cardiovascular complications, even at a very early age in life. The root causes of pediatric obesity remain incompletely understood. The obesity epidemic together with the relationship of obesity to the growing population burden of chronic disease presents unprecedented research opportunities and challenges. Decades of obesity-related research funded by governments around the world have yielded many important discoveries about both etiological pathways and preventive or therapeutic interventions. Yet, there is a sense that the problem is outpacing these research efforts. Obesity poses a significant risk for the development of cardiovascular disease (CVD) , diabetes and certain cancers thereby shortening life expectancy. Nevertheless, many obese individuals do not develop any of these comorbidities. One hypothesis explaining this dilemma is that total body fat is not the culprit of adverse health in obesity rather the relative proportion of lipids in various fat depots is what determines the metabolic risk. In this review, we describe the role of altered fat partitioning in youth onset obesity and its relation to fatty liver and T2D during adolescence.

Is the body composition development in premature infants associated with a distinctive nuclear magnetic resonance metabolomic profiling of urine?

OBJECTIVE

Preterm infants' body composition at term-corrected age differs from that of term infants but appears to be similar at the age of 3 months. The aim of this study was to compare the metabolomic pattern of preterm infants at term and at 3 months with that of term infants and to determine its association with body composition development.

METHOD

We designed a pilot study. Growth and body composition were evaluated by an air displacement plethysmography system in 13 preterm infants and seven term newborns at term and at 3 months of corrected age. Urine samples were collected at the same time points and analysed by nuclear magnetic resonance.

RESULTS

At term-corrected age, preterm infants showed a higher fat mass percentage compared with that of term newborns, whereas at 3 months of corrected age, the body composition parameters were similar between the groups. At the first time point, nuclear magnetic resonance analysis showed a urinary increase in choline/phosphocholine, betaine and glucose in preterm infants. At the second time point, the preterm group exhibited a urinary increase in choline/phosphocholine and a decrease in betaine.

CONCLUSIONS

The increased urinary excretion of choline, a betaine precursor, could reflect a potential altered metabolism in preterm infants.

Effects of Exercise Training Alone on Depot-Specific Body Fat Stores in Youth: Review of Recent Literature

The prevalence of childhood obesity has increased at an alarming rate. The increased obesity rate in pediatrics parallels the increased risks for developing metabolic abnormalities, such as insulin resistance, type 2 diabetes, and nonalcoholic fatty liver disease. In particular, the strong relationship between obesity and such health consequences is well explained by the excessive accumulation of depot-specific body adiposity, such as visceral adipose tissue, intrahepatic lipid content, intermuscular adipose tissue, and/or intramyocellular lipid content. Limited evidence suggests that both aerobic and resistance exercise alone, independent of weight loss, can be an effective therapeutic strategy for improving risk markers of metabolic abnormalities as well as inducing positive changes in depot-specific body adiposity in obese children and adolescents. However, the independent role of exercise alone (without calorie restriction) in body fat distribution is still unclear, and the results are less conclusive in pediatrics. In this brief review, the effects of aerobic and resistance exercise on depot-specific body adiposity changes in children and adolescents are discussed.

Investigating the link of ACAD10 deficiency to type 2 diabetes mellitus

The Native American Pima population has the highest incidence of insulin resistance (IR) and type 2 diabetes mellitus (T2DM) of any reported population, but the pathophysiologic mechanism is unknown. Genetic studies in Pima Indians have linked acyl-CoA dehydrogenase 10 (ACAD10) gene polymorphisms, among others, to this predisposition. The gene codes for a protein with a C-terminus region that is structurally similar to members of a family of flavoenzymes-the acyl-CoA dehydrogenases (ACADs)-that catalyze α,β-dehydrogenation reactions, including the first step in mitochondrial FAO (FAO), and intermediary reactions in amino acids catabolism. Dysregulation of FAO and an increase in plasma acylcarnitines are recognized as important in the pathophysiology of IR and T2DM. To investigate the deficiency of ACAD10 as a monogenic risk factor for T2DM in human, an Acad-deficient mouse was generated and characterized. The deficient mice exhibit an abnormal glucose tolerance test and elevated insulin levels. Blood acylcarnitine analysis shows an increase in long-chain species in the older mice. Nonspecific variable pattern of elevated short-terminal branch-chain acylcarnitines in a variety of tissues was also observed. Acad10 mice accumulate excess abdominal adipose tissue, develop an early inflammatory liver process, exhibit fasting rhabdomyolysis, and have abnormal skeletal muscle mitochondria. Our results identify Acad10 as a genetic determinant of T2DM in mice and provide a model to further investigate genetic determinants for insulin resistance in humans.

Impact of Severe Obesity on Cardiovascular Risk Factors in Youth

OBJECTIVE

To compare cardiovascular risk factor clustering (CVRFC) in severely obese youth with those with lower degrees of obesity.

STUDY DESIGN

We divided a childhood obesity clinic derived cohort into the degrees of obesity (class I, II, and III) and added a "class IV" category corresponding to >160% of the 95th centile of body mass index (BMI) for age and sex. In a cross-sectional analysis, we investigated the presence of CVRFC in 2244 participants; in 621 who were followed longitudinally, we investigated the determinants of endpoint CVRFC.

RESULTS

Class IV obesity was associated with increased risk for CVRFC compared with overweight (OR = 17.26, P < .001) at a similar magnitude to class III obesity (OR = 17.26, P < .001). Male children were at greater risk for presence of CVRFC (OR = 1.57, P = .03) compared with female children. Adiponectin (OR = 0.90, P < .001) and leptin levels (OR = 0.98, P = .008) were protective, independent of degree of obesity. Baseline class IV obesity was associated with increased risk compared with overweight of having CVRFC at follow-up (OR = 5.76, P = .001), to a similar extent as class III obesity (OR = 5.36, P = .001). Changes in the degree of obesity were significant predictors of CVRFC on follow-up (OR = 1.04, P < .01 per percent BMI change).

CONCLUSIONS

The metabolic risk associated with obesity in childhood is conferred prior to reaching class IV obesity. An individualized risk stratification approach in children with severe obesity should be based on presence of complications rather than simple BMI cutoffs.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01967849.

Dynamic Change in Insulin Resistance Induced by Free Fatty Acids Is Unchanged Though Insulin Sensitivity Improves Following Endurance Exercise in PCOS

Background: Insulin resistance (IR) is the hallmark of PCOS and it is known that exercise may decrease it. What is unknown is whether exercise may mechanistically alter the underlying IR, attenuating the dynamic lipid induced IR in insulin resistant subjects. Methods: 12 women with polycystic ovary syndrome (PCOS) and 10 age and body mass index matched controls completed an 8 week supervised exercise program at 60% maximal oxygen consumption. Before and after the exercise program, all participants underwent hyperinsulinaemic euglycaemic clamps with either saline or intralipid infusions. Skewed data were log transformed and expressed as mean ± SEM. Results: Before exercise, women with PCOS had a higher HOMA-IR and lower VO₂ max than controls. Compared to saline, lipid infusion lowered the rate of insulin stimulated glucose disposal (M value; mg/kg/min) by 67 ± 5% (from 0.5 ± 0.03 to -0.25 ± 0.2, p = 0.01) in PCOS, and by 49 ± 7% (from 0.65 ± 0.06 to 0.3 ± 0.1, p = 0.01) in controls. The M value was significantly less in PCOS compared to controls for both saline (p < 0.01) and lipid (p < 0.05). Endurance exercise in PCOS improved VO₂ max and HOMA-IR, but not weight, to those of pre-exercise control subjects. The glucose disposal rate during the lipid infusion was reduced following exercise in PCOS, indicating decreased IR (67 ± 5 vs. 50 ± 7%, p = 0.02), but IR was not altered in controls (49 ± 7 vs. 45 ± 6%, p = 0.58). The incrementally increased IR induced by the lipid infusion did not differ between controls and PCOS. Conclusion: Insulin sensitivity improved with exercise in the PCOS group alone showing that IR can be modified, though likely transiently. However, the maximal IR response to the lipid infusion did not differ within and between control and PCOS subjects, indicating that the fundamental mechanism underlying insulin resistance was unchanged with exercise. Precis: Maximal insulin resistance induced by lipid infusion determined at baseline and 8 weeks after exercise in control and PCOS women did not differ, though insulin sensitivity increased in PCOS after exercise.

Insulin Resistance, Prediabetes, Metabolic Syndrome: What Should Every Pediatrician Know?

The Metabolic syndrome describes a clustering of typical cardiovascular risk factors. The syndrome is also known as "Insulin Resistance syndrome" as a substantial part of the pathophysiology is driven by resistance to the metabolic effects of insulin. The major cause of insulin resistance in childhood is a typical lipid partitioning pattern characterized by increased deposition of lipids within insulin responsive tissues, such as the liver and skeletal muscle and within the viscera. This lipid deposition pattern is also associated with infiltration of intra-abdominal tissues with cells of the immune system, inducing systemic, low-grade inflammation typically observed in insulin resistant obese children and adolescents. Several clues derived from a careful history and physical examination, along with a basic laboratory workup, provide clues in regards to risk stratification in obese children.

Prediabetes in youth - mechanisms and biomarkers

Obesity has been estimated to decrease life expectancy by as little as 0.8 to as much as 7 years being the second leading cause of preventable death in the United States after smoking. Along with the increase in the prevalence of obesity, there has been a dramatic rise of the prevalence of prediabetes and type 2 diabetes among adolescents. Despite that, very little is known about the pathogenesis of these conditions in pediatrics and about how we could detect prediabetes in an early stage in order to prevent full blown diabetes. In this review we summarize the current knowledge on the pathophysiology of prediabetes and type 2 diabetes in adolescents and describe how biomarkers of beta-cell function might help identifying those individuals who are prone to progress from normal glucose tolerance towards prediabetes and overt type 2 diabetes. To better understand and fight this disease, we will need to explore and develop novel therapeutic strategies and individuate more sensitive and specific biomarkers that can allow an earlier detection of the disease.

The rs7903146 Variant in the TCF7L2 Gene Increases the Risk of Prediabetes/Type 2 Diabetes in Obese Adolescents by Impairing β-Cell Function and Hepatic Insulin Sensitivity

OBJECTIVE

In this study, we aimed to explore the mechanism by which TCF7L2 rs7903146 risk allele confers susceptibility to impaired glucose tolerance (IGT) or type 2 diabetes (T2D) in obese adolescents.

RESEARCH DESIGN AND METHODS

The rs7903146 variant in the TCF7L2 gene was genotyped in a multiethnic cohort of 955 youths. All subjects underwent an oral glucose tolerance test with the use of the Oral Minimal Model to assess insulin secretion, and 33 subjects underwent a hyperinsulinemic-euglycemic clamp. In 307 subjects, a follow-up oral glucose tolerance test was repeated after 3.11 ± 2.36 years.

RESULTS

The TCF7L2 rs7903146 risk allele was associated with higher 2-h glucose levels in Caucasians (P = 0.006) and African Americans (P = 0.009), and a trend was seen also in Hispanics (P = 0.072). Also, the T allele was associated with decreased β-cell responsivity and IGT (P < 0.05). Suppression of endogenous hepatic glucose production was lower in subjects with the risk variant (P = 0.006). Finally, the odds of showing IGT/T2D at follow-up were higher in subjects carrying the minor allele (odds ratio 2.224; 95% CI 1.370-3.612; P = 0.0012).

CONCLUSIONS

The rs7903146 variant in the TCF7L2 gene increases the risk of IGT/T2D in obese adolescents by impairing β-cell function, and hepatic insulin sensitivity predicts the development of IGT/T2D over time.

A Branched-Chain Amino Acid-Related Metabolic Signature Characterizes Obese Adolescents with Non-Alcoholic Fatty Liver Disease

Dysregulation of several metabolite pathways, including branched-chain amino acids (BCAAs), are associated with Non-Alcoholic Fatty Liver Disease (NAFLD) and insulin resistance in adults, while studies in youth reported conflicting results. We explored whether, independently of obesity and insulin resistance, obese adolescents with NAFLD display a metabolomic signature consistent with disturbances in amino acid and lipid metabolism. A total of 180 plasma metabolites were measured by a targeted metabolomic approach in 78 obese adolescents with (n = 30) or without (n = 48) NAFLD assessed by magnetic resonance imaging (MRI). All subjects underwent an oral glucose tolerance test and subsets of patients underwent a two-step hyperinsulinemic-euglycemic clamp and/or a second MRI after a 2.2 ± 0.8-year follow-up. Adolescents with NAFLD had higher plasma levels of valine (p = 0.02), isoleucine (p = 0.03), tryptophan (p = 0.02), and lysine (p = 0.02) after adjustment for confounding factors. Circulating BCAAs were negatively correlated with peripheral and hepatic insulin sensitivity. Furthermore, higher baseline valine levels predicted an increase in hepatic fat content (HFF) at follow-up (p = 0.01). These results indicate that a dysregulation of BCAA metabolism characterizes obese adolescents with NAFLD independently of obesity and insulin resistance and predict an increase in hepatic fat content over time.

Glucose and Lipid Dysmetabolism in a Rat Model of Prediabetes Induced by a High-Sucrose Diet

Glucotoxicity and lipotoxicity are key features of type 2 diabetes mellitus, but their molecular nature during the early stages of the disease remains to be elucidated. We aimed to characterize glucose and lipid metabolism in insulin-target organs (liver, skeletal muscle, and white adipose tissue) in a rat model treated with a high-sucrose (HSu) diet. Two groups of 16-week-old male Wistar rats underwent a 9-week protocol: HSu diet (n = 10)-received 35% of sucrose in drinking water; Control (n = 12)-received vehicle (water). Body weight, food, and beverage consumption were monitored and glucose, insulin, and lipid profiles were measured. Serum and liver triglyceride concentrations, as well as the expression of genes and proteins involved in lipid biosynthesis were assessed. The insulin-stimulated glucose uptake and isoproterenol-stimulated lipolysis were also measured in freshly isolated adipocytes. Even in the absence of obesity, this rat model already presented the main features of prediabetes, with fasting normoglycemia but reduced glucose tolerance, postprandial hyperglycemia, compensatory hyperinsulinemia, as well as decreased insulin sensitivity (resistance) and hypertriglyceridemia. In addition, impaired hepatic function, including altered gluconeogenic and lipogenic pathways, as well as increased expression of acetyl-coenzyme A carboxylase 1 and fatty acid synthase in the liver, were observed, suggesting that liver glucose and lipid dysmetabolism may play a major role at this stage of the disease.

Insulin Resistance, Hyperinsulinemia, and Mitochondria Dysfunction in Nonobese Girls With Polycystic Ovarian Syndrome

Objective:

Obese girls with polycystic ovarian syndrome (PCOS) have decreased insulin sensitivity (IS), muscle mitochondrial dysfunction and increased liver fat, which may contribute to their increased risk for type 2 diabetes. Less is known regarding normal-weight girls with PCOS.

Methods:

Normal-weight girls with PCOS [n =18, age 15.9 ± 1.8 years, body mass index (BMI) percentile 68 ± 18] and normal-weight controls (NWC; n = 20; age 15.0 ± 2.1 years, BMI percentile 60 ± 21) were studied. Tissue-specific IS was assessed with a four-phase hyperinsulinemic-euglycemic clamp with isotope tracers and a 2-hour oral glucose tolerance test (OGTT). Hepatic fat was determined using magnetic resonance imaging. Postexercise muscle mitochondrial function was assessed with ³¹P MR spectroscopy.

Results:

Both groups had similar demographics, anthropomorphics, physical attributes, habitual physical activity levels and fasting laboratory values, except for increased total testosterone and DHEAS in PCOS. Clamp-assessed peripheral IS was lower in PCOS (10.4 ± 2.4 mg/kg/min vs 12.7 ± 2.1; P = 0.024). The 120-minute OGTT insulin and glucose concentrations were higher in PCOS (114 IU/mL ± 26 vs 41 ± 25, P = <0.001 and 119 ± 22 mg/dL vs 85 ± 23, P = 0.01, respectively). Muscle mitochondrial ADP and phosphocreatine time constants were slower in PCOS. Despite a higher percentage liver fat in PCOS, hepatic IS was similar between groups, as was adipose IS.

Conclusions:

Normal-weight girls with PCOS have decreased peripheral IS and muscle mitochondrial dysfunction, abnormal glucose disposal, relative postprandial hyperinsulinemia, and increased hepatic fat compared to NWC. Despite a normal BMI, multiple aspects of metabolism appear altered in normal-weight girls with PCOS.

Adolescent Obesity and Insulin Resistance: Roles of Ectopic Fat Accumulation and Adipose Inflammation

As a consequence of the global rise in the prevalence of adolescent obesity, an unprecedented phenomenon of type 2 diabetes has emerged in pediatrics. At the heart of the development of type 2 diabetes lies a key metabolic derangement: insulin resistance (IR). Despite the widespread occurrence of IR affecting an unmeasurable number of youths worldwide, its pathogenesis remains elusive. IR in obese youth is a complex phenomenon that defies explanation by a single pathway. In this review we first describe recent data on the prevalence, severity, and racial/ethnic differences in pediatric obesity. We follow by elucidating the initiating events associated with the onset of IR, and describe a distinct "endophenotype" in obese adolescents characterized by a thin superficial layer of abdominal subcutaneous adipose tissue, increased visceral adipose tissue, marked IR, dyslipidemia, and fatty liver. Further, we provide evidence for the cellular and molecular mechanisms associated with this peculiar endophenotype and its relations to IR in the obese adolescent.

Differences in β-cell function and insulin secretion in Black vs. White obese adolescents: do incretin hormones play a role?

Black youth are at higher risk for type 2 diabetes (T2D) than their White peers. Previously we demonstrated that for the same degree of insulin sensitivity, Black youth have an upregulated β-cell function and insulin hypersecretion, in response to intravenous (iv) glucose, compared with Whites. To investigate if the same holds true during an oral glucose challenge and because of the important role of glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) in augmenting insulin secretion, we examined β-cell function and incretin hormones in 85 Black and 78 White obese adolescents, with normal glucose tolerance (NGT), during a 2-h oral glucose tolerance test (OGTT) with mathematical modeling of plasma glucose and C-peptide concentrations to assess β-cell glucose sensitivity (βCGS), rate sensitivity, potentiation factor, and insulin sensitivity. Incretin, pancreatic polypeptide, and glucagon concentrations were measured during the OGTT. Black obese youth had a heightened early insulin secretion together with significantly greater βCGS, rate sensitivity, and potentiation factor compared with Whites, with no differences in incretin and glucagon concentrations. Basal and stimulated insulin clearance was lower (p = 0.001) in Black vs. White youth. In conclusion, during an OGTT Black obese youth with NGT demonstrate a pronounced early insulin secretion jointly with heightened β-cell glucose sensitivity, rate sensitivity, and potentiation factor. These racial disparities in β-cell function and the pathophysiological components of T2D are unlikely to be attributed to incretin hormones and remain to be investigated further to explain the metabolic basis for the enhanced risk of T2D in back youth.

High predictability of impaired glucose tolerance by combining cardiometabolic screening parameters in obese children

BACKGROUND

There is debate on which overweight and obese children should be screened for the presence of impaired glucose tolerance (IGT) by oral glucose tolerance testing (OGTT). The objective of the study was to identify risk factors predictive of the presence of IGT.

METHODS

In a cohort of overweight children, who underwent OGTT, we determined the association of anthropometric and laboratory parameters with IGT and whether combining parameters improved the sensitivity of screening for IGT.

RESULTS

Out of 145 patients, IGT was present in 11, of whom two had impaired fasting glucose (IFG). Elevated blood pressure (p=0.025) and elevated liver enzymes (p=0.003) were associated with IGT, whereas IFG was not (p=0.067), screening patients with either one of these parameters predicted IGT with a high sensitivity of 1.00, and a number needed to screen of 5.7.

CONCLUSIONS

Screening all patients with either IFG, presence of elevated blood pressure and elevated liver enzymes, significantly increases predictability of IGT compared to using IFG alone.

Trends in Child Obesity and Underweight in Spain by Birth Year and Age, 1983 to 2011

INTRODUCTION AND OBJECTIVES

The prevalences of child obesity and overweight are increasing worldwide and are a significant public health issue, particularly in terms of long-term cardiovascular risk profiles, which continue into adulthood unless obesity is reversed. Accurately identifying trends and at-risk subgroups is crucial to correctly target public health initiatives. The objective of this study was to examine changes in the prevalences of child obesity and underweight in Spain from 1983 to 2011 taking into consideration both age and birth year.

METHODS

A series of cross-sectional studies representative of the pediatric population in Spain between 1987 and 2011 was used to calculate the prevalence and trends of excess weight and underweight in girls and boys aged 2 to 14 years per survey year and per birth year.

RESULTS

The overall prevalence of overweight and obesity remained relatively stable. The prevalence of overweight in boys aged 10 to 14 years increased from 13.9% to 22.2%. The prevalence of obesity in girls aged 2 to 5 years decreased from 30% to 19.8%, whereas the prevalence of underweight in this group increased from 13.7% to 22.6%.

CONCLUSIONS

Child obesity trends in Spain over the last 2 decades appear to be stable with some fluctuations, but the trends differ depending on age and sex, and have stabilized at too high a level. The prevalence of underweight also appears to have increased and should be considered alongside excess weight when designing and implementing child health and weight measures.

Long-term feeding of high-fat plus high-fructose diet induces isolated impaired glucose tolerance and skeletal muscle insulin resistance in miniature pigs

BACKGROUND

During the prediabetic development, the changes in β-cell function and tissue-specific insulin resistance have been described. However, there are conflicting views in insulin secretory capacity between early clinical observation and recent proposed mathematical model. On the basis of digestive and metabolic similarities with humans, swine have great potential as an animal model to investigate the progressive mechanisms of prediabetes. The aim of this study was to investigate the insulin secretory response and tissue-specific insulin resistance in a dietary-induced prediabetic porcine model.

METHODS

Adult male Taiwan Lee-Sung miniature pigs were randomized into two groups: (1) low-fat diet and (2) high-fat plus high-fructose diet (HFHF; 20.9% crude fat and 17.8% fructose). During the 12-month dietary intervention, body weights and blood glucose levels were measured monthly. Intravenous glucose tolerance test was used for measuring glucose tolerance and insulin secretory capacity. At the end of the experiment, liver and soleus muscle specimens were collected for ex vivo insulin sensitivity testing.

RESULTS

The results showed that the HFHF group had obesity, hyperinsulinemia, and dyslipidemia, but normal fasting glucose levels. The HFHF pigs exhibited enhanced first- and second-phase insulin secretion and high 2-h postload glucose levels in intravenous glucose tolerance test. Furthermore, the skeletal muscle specimens from the HFHF group were desensitized to insulin stimulation as shown by the lack of AKT Ser473 phosphorylation; however, the liver specimens remained a normal response.

CONCLUSIONS

In conclusion, the HFHF diet-fed pigs developed isolated impaired glucose tolerance corresponding to prediabetes with an intense insulin secretory response and skeletal muscle insulin resistance.

1H-MRS measured ectopic fat in liver and muscle is associated with the metabolic syndrome in Danish girls but not in boys with overweight and obesity

Background

The metabolic syndrome (MetS) is a complication to overweight and obesity, which can be observed already in childhood. Ectopic lipid accumulation in muscle and liver has been shown to associate with the development of insulin resistance and dyslipidemia. Thus, the interaction between MetS and ectopic fat may offer clinical relevance.

Objectives

To investigate the prevalence of MetS, or components hereof, and ectopic fat accumulation in liver and skeletal muscle tissue in children, as well as interactions between these.

Methods

Two‐hundred‐and‐sixteen children and adolescents (95 boys) with overweight/obesity were investigated, as well as 47 controls (22 boys) with normal weight. The assessments included anthropometry, fasting blood biochemistry and blood pressure measurements. Liver and muscle lipid contents were assessed by proton magnetic resonance spectroscopy.

Results

We observed an odds ratio in girls with overweight/obesity of 12.2 (95% confidence interval: [3.8; 49.0]) for exhibiting MetS when hepatic steatosis was present, whereas no association was observed in boys with overweight/obesity (odds ratio 0.7 [0.2; 2.7]). The odds ratio of exhibiting MetS in the presence of muscular steatosis was 3.5 [1.4; 9.5] in girls with overweight/obesity and 1.0 [0.2; 5.6] in boys with overweight/obesity. Similar results were seen for girls with overweight/obesity exhibiting concurrent hepatic and muscular steatoses.

Conclusion

Hepatic and muscular steatoses were associated with MetS among girls, but not among boys with overweight/obesity.

No difference in exogenous carbohydrate oxidation during exercise in children with and without impaired glucose tolerance

The capacity to match carbohydrate (CHO) utilization with availability is impaired in insulin-resistant, obese adults at rest. Understanding exogenous carbohydrate (CHOexo) oxidation during exercise and its association to insulin resistance (IR) is important, especially in children at risk for type 2 diabetes. Our objective was to examine the oxidative efficiency of CHOexo during exercise in obese children with normal glucose tolerance (NGT) or impaired glucose tolerance (IGT). Children attended two visits and were identified as NGT (n = 22) or IGT (n = 12) based on 2-h oral glucose tolerance test (OGTT) glucose levels of <7.8 mmol/l or ≥7.8 mmol/l, respectively. Anthropometry, body composition, and aerobic fitness (V̇o2max) were assessed. Insulin and glucose at baseline, 30, 60, 90, and 120 min during the OGTT were used to calculate measures of insulin sensitivity. On a separate day, a (13)C-enriched CHO drink was ingested before exercise (3 × 20 min bouts) at 45% V̇o2max Breath measurements were collected to calculate CHOexo oxidative efficiency. CHOexo oxidative efficiency during exercise was similar in IGT (17.0 ± 3.6%) compared with NGT (17.1 ± 4.4%) (P = 0.90) despite lower whole body insulin sensitivity in IGT at rest (P = 0.02). Area under the curve for insulin (AUCins) measured at rest during the OGTT was greater in IGT compared with NGT (P = 0.04). The ability of skeletal muscle to utilize CHOexo was not impaired during exercise in children with IGT.

Altered Brain Response to Drinking Glucose and Fructose in Obese Adolescents

Increased sugar-sweetened beverage consumption has been linked to higher rates of obesity. Using functional MRI, we assessed brain perfusion responses to drinking two commonly consumed monosaccharides, glucose and fructose, in obese and lean adolescents. Marked differences were observed. In response to drinking glucose, obese adolescents exhibited decreased brain perfusion in brain regions involved in executive function (prefrontal cortex [PFC]) and increased perfusion in homeostatic appetite regions of the brain (hypothalamus). Conversely, in response to drinking glucose, lean adolescents demonstrated increased PFC brain perfusion and no change in perfusion in the hypothalamus. In addition, obese adolescents demonstrated attenuated suppression of serum acyl-ghrelin and increased circulating insulin level after glucose ingestion; furthermore, the change in acyl-ghrelin and insulin levels after both glucose and fructose ingestion was associated with increased hypothalamic, thalamic, and hippocampal blood flow in obese relative to lean adolescents. Additionally, in all subjects there was greater perfusion in the ventral striatum with fructose relative to glucose ingestion. Finally, reduced connectivity between executive, homeostatic, and hedonic brain regions was observed in obese adolescents. These data demonstrate that obese adolescents have impaired prefrontal executive control responses to drinking glucose and fructose, while their homeostatic and hedonic responses appear to be heightened. Thus, obesity-related brain adaptations to glucose and fructose consumption in obese adolescents may contribute to excessive consumption of glucose and fructose, thereby promoting further weight gain.

Adipose Insulin Resistance in Obese Adolescents Across the Spectrum of Glucose Tolerance

CONTEXT

Adipocytes represent an important insulin-responsive tissue taking an active part in glucose metabolism.

OBJECTIVE

This study sought to assess adipose tissue insulin resistance (IR) across the spectrum of glucose tolerance and to test its relation with free fatty acid (FFA) suppression during an oral glucose tolerance test (OGTT).

DESIGN AND SETTING

A cross-sectional analysis of a pediatric clinic-derived cohort of obese adolescents.

PATIENTS OR OTHER PARTICIPANTS

Participants age 7-20 y with a body mass index that exceeded the 95th percentile for their age and sex.

INTERVENTION(S)

A standard oral glucose tolerance test.

MAIN OUTCOME MEASURES

The adipose tissue insulin resistance index (calculated as the product of fasting insulin and FFA concentrations) (Adipose IR) and the area under curve of FFAs during the OGTT were compared between glucose tolerance categories.

RESULTS

A total of 962 obese children and adolescents participated in this study. Adipose IR significantly increased across glucose tolerance categories (P for trend < .001). Within the normal glucose tolerance participants, an increase in adipose IR was observed related to an increase in 2-hr glucose levels. In a subsample of participants who underwent abdominal imaging for determination of lipid partitioning (n = 115), a tight relation of visceral fat (r = 0.34; P < .001) and the visceral/sc fat ratio (r = 0.55; P < .001) with the Adipose IR index was evident. Greater area under the curve FFAs (lower FFA suppression) during the OGTT was evident with worsening glucose tolerance (P for trend < .001). Glucose tolerance category, degree of obesity (body mass index-z score), IL-6, and low adiponectin emerged as significant predictors of the Adipose IR.

CONCLUSIONS

Adipose IR is associated with reduced suppression of FFAs during the OGTT and with an altered adipocytokine profile. The negative relation with insulin secretion deserves further longitudinal investigation in the context of deteriorating glucose tolerance.

Dietary Fatty Acids Differentially Associate with Fasting Versus 2-Hour Glucose Homeostasis: Implications for The Management of Subtypes of Prediabetes

Over-nutrition has fuelled the global epidemic of type 2 diabetes, but the role of individual macronutrients to the diabetogenic process is not well delineated. We aimed to examine the impact of dietary fatty acid intake on fasting and 2-hour plasma glucose concentrations, as well as tissue-specific insulin action governing each. Normoglycemic controls (n = 15), athletes (n = 14), and obese (n = 23), as well as people with prediabetes (n = 10) and type 2 diabetes (n = 11), were queried about their habitual diet using a Food Frequency Questionnaire. All subjects were screened by an oral glucose tolerance test (OGTT) and studied using the hyperinsulinemic/euglycemic clamp with infusion of 6,62H2-glucose. Multiple regression was performed to examine relationships between dietary fat intake and 1) fasting plasma glucose, 2) % suppression of endogenous glucose production, 3) 2-hour post-OGTT plasma glucose, and 4) skeletal muscle insulin sensitivity (glucose rate of disappearance (Rd) and non-oxidative glucose disposal (NOGD)). The %kcal from saturated fat (SFA) was positively associated with fasting (β = 0.303, P = 0.018) and 2-hour plasma glucose (β = 0.415, P<0.001), and negatively related to % suppression of hepatic glucose production (β = -0.245, P = 0.049), clamp Rd (β = -0.256, P = 0.001) and NOGD (β = -0.257, P = 0.001). The %kcal from trans fat was also negatively related to clamp Rd (β = -0.209, P = 0.008) and NOGD (β = -0.210, P = 0.008). In contrast, the %kcal from polyunsaturated fat (PUFA) was negatively associated with 2-hour glucose levels (β = -0.383, P = 0.001), and positively related to Rd (β = 0.253, P = 0.007) and NOGD (β = 0.246, P = 0.008). Dietary advice to prevent diabetes should consider the underlying pathophysiology of the prediabetic state.

Multidisciplinary care of obese children and adolescents for one year reduces ectopic fat content in liver and skeletal muscle

Background

Ectopic fat deposition in liver and skeletal muscle tissue is related to cardiovascular disease risk and is a common metabolic complication in obese children. We evaluated the hypotheses of ectopic fat in these organs could be diminished following 1 year of multidisciplinary care specialized in childhood obesity, and whether this reduction would associate with changes in other markers of metabolic function.

Methods

This observational longitudinal study evaluated 40 overweight children and adolescents enrolled in a multidisciplinary treatment protocol at the Children’s Obesity Clinic, Holbæk, Denmark. The participants were assessed by anthropometry, fasting blood samples (HbA1c, glucose, insulin, lipids, and biochemical variables of liver function), and liver and muscle fat content assessed by magnetic resonance spectroscopy at enrollment and following an average of 12.2 months of care. Univariate linear regression models adjusted for age, sex, treatment duration, baseline degree of obesity, and pubertal developmental stage were used for investigating possible associations.

Results

The standard deviation score (SDS) of baseline median body mass index (BMI) was 2.80 (range: 1.49–3.85) and the median age was 14 years (10–17). At the end of the observational period, the 40 children and adolescents (21 girls) significantly decreased their BMI SDS, liver fat, muscle fat, and visceral adipose tissue volume. The prevalence of hepatic steatosis changed from 28 to 20 % (p = 0.26) and the prevalence of muscular steatosis decreased from 75 to 45 % (p = 0.007).

Changes in liver and muscle fat were independent of changes in BMI SDS, baseline degree of obesity, duration of treatment, age, sex, and pubertal developmental stage.

Conclusions

A 1-year multidisciplinary intervention program in the setting of a childhood obesity outpatient clinic confers a biologically important reduction in liver and muscle fat; metabolic improvements that are independent of the magnitude of concurrent weight loss.

Trial registration

ClinicalTrials.gov registration number: NCT00928473, the Danish Childhood Obesity Biobank. Registered June 25, 2009.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-015-0513-6) contains supplementary material, which is available to authorized users.

The prevalence, risk factors, and screening measure for prediabetes and diabetes among Emirati overweight/obese children and adolescents

Background

The aim of the study was to estimate the prevalence of prediabetes and type 2 diabetes (T2D) among overweight/obese children and adolescents using different diagnostic/screening methods in comparison.

Methods

We recruited overweight/obese Emirati students; grade 6–12 (age 11–17 years) from 16 government schools in Sharjah (UAE). Anthropometric, demographic, and clinical history data was measured by standard methods. Body mass index (BMI) was categorized according to BMI percentile charts for age and sex – CDC. Capillary fasting blood glucose (FBG) and glycated hemoglobin (HbA1c) were measured by finger prick test, followed by confirmatory oral glucose tolerance tests (OGTT) and venous HbA1c for students with abnormal capillary FBG and/or HbA1c.

Results

Of a total of 1034 participants (45 % females) median age 14.7 years, 443 (43 %) students had abnormal screening results. The prevalence of prediabetes and T2D was 5.4 % and 0.87 %, respectively, based on OGTT (gold standard). HbA1c showed a considerable discrepancy regarding the prevalence of prediabetes (21.9 %), but not diabetes. There was a statistically significant difference in the BMI Z-scores between the three different groups of students showing normal glycemic testing, prediabetes and T2D (p = 0.041). Univariate logistic regression analysis showed that glycemic status was significantly associated with family history of T2D first-degree relatives [OR 1.87: 95 % CI: 1.04–3.36; P = 0.036], parents employment [OR 1.79: 95 % CI: 1.06–3.02; P = 0.029] and levels of triglycerides [OR 2.28: 95 % CI: 1.11–4.68; P = 0.024].

Conclusions

The prevalence of prediabetes and diabetes was high among overweight/obese Emirati children and adolescents. The numbers for prediabetes were considerably higher when using HbA1c as compared to OGTT. Overall adiposity, family history of T2D, employment and high levels of triglycerides were risk factors associated with abnormal glycemic testing.

Improvements of Glucose and Lipid Metabolism After Jejuno-ileal Circuit Procedure in a Non-obese Diabetic Rat Model

BACKGROUND

In a recent study, we showed a jejuno-ileal circuit (JIC) procedure that effectively improved glucose homeostasis, but the intrinsic mechanism requires further studies. Furthermore, the role of JIC in lipid metabolism is also unknown. Given that adiposity aggravates insulin sensitivity, we hypothesize that the JIC procedure improves fat metabolism and thus further contributes to diabetic remission. The aim of this study was to investigate the effects of JIC surgery on lipid metabolism and glucose homeostasis in a non-obese diabetic rat model.

METHODS

Fourteen high-fat diet and low-dose streptozotocin-induced diabetic rats were randomly divided into JIC and sham-JIC groups. Body weight, food intake, glucose tolerance, insulin resistance, serum lipid parameters, glucagon-like peptide 1 (GLP-1), and adipose-derived hormones were measured. At 12 weeks postoperatively, the expressions of hepatic fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) were measured by Western blot. The lipid content of liver was assessed by hematoxylin-eosin staining and Oil Red O staining. The enteroendocrine cells in the distal ileum were examined by immunohistochemical staining.

RESULTS

Relative to the sham group, the JIC rats exhibited significant improvements in glucose tolerance, insulin resistance, and dyslipidemia without weight loss, showing increased GLP-1 and adiponectin and decreased leptin. JIC also reduced the expression of FAS and ACC in the liver, exhibited improved hepatic fat content, and raised the levels of GLP-1 and chromogranin A in the distal gut.

CONCLUSIONS

JIC alleviated lipometabolic disorders in hyperglycemic rats, which may contribute to the amelioration of insulin sensitivity and glycemic control.

Responses to Fasting and Glucose Loading in a Cohort of Well Children with Spinal Muscular Atrophy Type II

OBJECTIVE

To examine the impact of fasting and glucose tolerance on selected metabolic variables in children with spinal muscular atrophy (SMA) type II in a well state, secondary to reports of glucose regulation abnormalities in SMA.

STUDY DESIGN

In this prospective pilot study, 6 children aged 7-11 years with SMA type II participated in an oral glucose tolerance test and a supervised medical fast during 2 overnight visits at the University of Utah. At baseline, a dual-energy x-ray absorptiometry scan was performed to determine body composition. Laboratory test results were obtained at baseline and in response to the respective interventions. Data analysis was descriptive. Prefasting and postfasting data were evaluated using the Wilcoxon signed-rank test.

RESULTS

Based on the dual-energy x-ray absorptiometry scan, all 6 children were variably obese at baseline. All 6 exhibited hyperinsulinemia, and 3 of 6 met formal American Diabetes Association criteria for impaired glucose tolerance. According to homeostatic insulin resistance calculations, 5 of the 6 participants were insulin-resistant. All 6 participants tolerated a monitored fast for 20 hours without hypoglycemia (blood glucose <54 mg/dL). Free fatty acid levels increased significantly from prefasting to postfasting, whereas levels of several plasma amino acids decreased significantly during fasting.

CONCLUSION

Children with SMA type II defined as obese using objective variables are at increased risk for impaired glucose tolerance regardless of whether or not they visually appear obese. Further studies are needed to determine the prevalence of impaired glucose tolerance and tolerance for fasting within the broader heterogeneous SMA population and to develop appropriate guidelines for intervention.

Changes in whole-body fat distribution, intrahepatic lipids, and insulin resistance of obese adolescents during a low-level lifestyle intervention

The aim of this study was to analyze changes in adipose tissue (AT) distribution, intrahepatic lipids (IHL), and insulin resistance (IR) among a group of obese adolescents undergoing a 7-months low-level lifestyle intervention. Thirty-nine obese Caucasian adolescents (mean age 13.9 years, body mass index standard deviation score (BMI-SDSLMS) 2.14) were included. AT and IHL were determined by T1-weighted magnetic resonance (MR) imaging and single-voxel MR spectroscopy; IR was estimated using the homeostatic model assessment (HOMA-IR). The lifestyle intervention led to a reduction of both BMI-SDSLMS (boys 2.27 to 2.17; girls 2.00 to 1.82) and HOMA-IR (boys 6.1 to 4.4 (p = 0.008); girls 6.2 to 4.7 (p = 0.030)). IHL dropped in both genders (boys 7.5 to 4.3 %; girls 4.6 to 3.4 %) positively correlating with HOMA-IR (boys r = 0.52; girls r = 0.68), while in contrast visceral AT did not change significantly.

CONCLUSIONS

Although the lifestyle intervention only slightly reduced BMI-SDSLMS, insulin sensitivity improved in both genders and came along with a marked reduction of IHL. This suggests that IHL might play the dominant role regarding insulin resistance in the youth, especially if compared to other AT compartments such as visceral AT.

WHAT IS KNOWN

• MR imaging/spectroscopy can be used to evaluate body fat distribution and intrahepatic lipids in the youth. • The strength of associations between body fat compartments and insulin resistance is under scientific debate.

WHAT IS NEW

• The study emphasizes that even a low-level lifestyle intervention has a beneficial effect. • The study suggests that intrahepatic lipids are an important factor in the development of insulin resistance.

Intramyocellular lipid content in subjects with impaired fasting glucose after telmisartan treatment, a randomised cross-over trial

Ectopic lipid accumulation in skeletal muscle is associated with insulin resistance. Telmisartan improves metabolic parameters in type 2 diabetic patients. The aim of our study was to evaluate the in vivo effect of telmisartan on intramyocellular lipid content (IMCL) in subjects with impaired fasting glucose (IFG) by magnetic resonance spectroscopy (MRS). We enrolled 10 subjects with IFG in a cross-over, placebo-controlled, randomized, double-blind trial, treated with 3 weeks of telmisartan (160 mg daily) or placebo. After completing each treatment, a hyperinsulinaemic euglycaemic clamp (1 mU/kg per min; 5 mmol/l; 120 min) to assess insulin action (metabolic clearance rate of glucose, MCR) and (1)H MRS of the m. tibialis anterior using a MR Scanner Siemens Vision operating at 1.5 T to evaluate IMCL content, were performed. Plasma adipokine levels were determined simultaneously. Telmisartan treatment resulted in a lower fasting plasma glucose (FPG) (p < 0.05), but insulin action was comparable to after placebo. Telmisartan did not affect IMCL content. After placebo, IMCL correlated negatively with total cholesterol (p < 0.001), MCR (p < 0.05) and adiponectin (p < 0.05) and positively with FPG (p < 0.05). After telmisartan treatment there was only a positive correlation between IMCL and TNFα (p < 0.05). IMCL content is related to parameters of glucose metabolism and insulin action in sedentary IFG subjects. A short telmisartan treatment did not affect the IMCL content despite its positive effect on FPG. The improvement in FPG was probably mediated through interference with other metabolic pathways.

Trends and Determinants of Oral Anti-Diabetic Initiation in Youth with Suspected Type 2 Diabetes

OBJECTIVE

To evaluate trends and identify predictors of treatment initiation of oral anti-diabetic drugs (OAD) in youth.

PATIENTS AND METHODS

We identified a select population of children, ages 8-18 years, with at least 13 months of continuous health plan coverage within the years 2001-2012 in a large US commercial insurance claims database. New use of an OAD was defined as the first claim for an outpatient dispensing following a 12-month wash out period. Treatment incidence was estimated monthly over the study period, and stratified by age, gender, geographic region, and provider specialty.

RESULTS

The median size of the source population during the study period was 2.2 million children. A total of 13,824 initiators (mean monthly incidence of 4.6 (95% CI = 3.6, 5.5) per 100,000 youths) were identified. Initiators were more likely to be females, age 15-18, from the southern region, and have visited a family practitioner (versus a general pediatrician) prior to initiation. Time trends demonstrate a 43% increase in initiation from 2002-2012, with a gradual decrease starting from early 2008.

CONCLUSION

Incidence of filled OAD medications in youth increased over time, especially for patients treated by family practitioners. Additional research is needed into factors influencing prescribing by family practitioners and pediatricians.

1H-MRS Measured Ectopic Fat in Liver and Muscle in Danish Lean and Obese Children and Adolescents

Objectives

This cross sectional study aims to investigate the associations between ectopic lipid accumulation in liver and skeletal muscle and biochemical measures, estimates of insulin resistance, anthropometry, and blood pressure in lean and overweight/obese children.

Methods

Fasting plasma glucose, serum lipids, serum insulin, and expressions of insulin resistance, anthropometry, blood pressure, and magnetic resonance spectroscopy of liver and muscle fat were obtained in 327 Danish children and adolescents aged 8–18 years.

Results

In 287 overweight/obese children, the prevalences of hepatic and muscular steatosis were 31% and 68%, respectively, whereas the prevalences in 40 lean children were 3% and 10%, respectively. A multiple regression analysis adjusted for age, sex, body mass index z-score (BMI SDS), and pubertal development showed that the OR of exhibiting dyslipidemia was 4.2 (95%CI: [1.8; 10.2], p = 0.0009) when hepatic steatosis was present. Comparing the simultaneous presence of hepatic and muscular steatosis with no presence of steatosis, the OR of exhibiting dyslipidemia was 5.8 (95%CI: [2.0; 18.6], p = 0.002). No significant associations between muscle fat and dyslipidemia, impaired fasting glucose, or blood pressure were observed.

Liver and muscle fat, adjusted for age, sex, BMI SDS, and pubertal development, associated to BMI SDS and glycosylated hemoglobin, while only liver fat associated to visceral and subcutaneous adipose tissue and intramyocellular lipid associated inversely to high density lipoprotein cholesterol.

Conclusion

Hepatic steatosis is associated with dyslipidemia and liver and muscle fat depositions are linked to obesity-related metabolic dysfunctions, especially glycosylated hemoglobin, in children and adolescents, which suggest an increased cardiovascular disease risk.

Maternal obesity characterized by gestational diabetes increases the susceptibility of rat offspring to hepatic steatosis via a disrupted liver metabolome

Maternal obesity is associated with a high risk for gestational diabetes mellitus (GDM), which is a common complication of pregnancy. The influence of maternal obesity and GDM on the metabolic health of the offspring is poorly understood. We hypothesize that GDM associated with maternal obesity will cause obesity, insulin resistance and hepatic steatosis in the offspring. Female Sprague-Dawley rats were fed a high-fat (45%) and sucrose (HFS) diet to cause maternal obesity and GDM. Lean control pregnant rats received low-fat (LF; 10%) diets. To investigate the interaction between the prenatal environment and postnatal diets, rat offspring were assigned to LF or HFS diets for 12 weeks, and insulin sensitivity and hepatic steatosis were evaluated. Pregnant GDM dams exhibited excessive gestational weight gain, hyperinsulinaemia and hyperglycaemia. Offspring of GDM dams gained more weight than the offspring of lean dams due to excess adiposity. The offspring of GDM dams also developed hepatic steatosis and insulin resistance. The postnatal consumption of a LF diet did not protect offspring of GDM dams against these metabolic disorders. Analysis of the hepatic metabolome revealed increased diacylglycerol and reduced phosphatidylethanolamine in the offspring of GDM dams compared to offspring of lean dams. Consistent with altered lipid metabolism, the expression of CTP:phosphoethanolamine cytidylyltransferase, and peroxisomal proliferator activated receptor-α mRNA was reduced in the livers of GDM offspring. GDM exposure programs gene expression and hepatic metabolite levels and drives the development of hepatic steatosis and insulin resistance in young adult rat offspring.

Targeting skeletal muscle mitochondria to prevent type 2 diabetes in youth

The prevalence of type 2 diabetes (T2D) has increased dramatically over the past two decades, not only among adults but also among adolescents. T2D is a systemic disorder affecting every organ system and is especially damaging to the cardiovascular system, predisposing individuals to severe cardiac and vascular complications. The precise mechanisms that cause T2D are an area of active research. Most current theories suggest that the process begins with peripheral insulin resistance that precedes failure of the pancreatic β-cells to secrete sufficient insulin to maintain normoglycemia. A growing body of literature has highlighted multiple aspects of mitochondrial function, including oxidative phosphorylation, lipid homeostasis, and mitochondrial quality control in the regulation of peripheral insulin sensitivity. Whether the cellular mechanisms of insulin resistance in adults are comparable to that in adolescents remains unclear. This review will summarize both clinical and basic studies that shed light on how alterations in skeletal muscle mitochondrial function contribute to whole body insulin resistance and will discuss the evidence supporting high-intensity exercise training as a therapy to circumvent skeletal muscle mitochondrial dysfunction to restore insulin sensitivity in both adults and adolescents.

Fitness is a determinant of the metabolic response to endurance training in adolescents at risk of type 2 diabetes mellitus

OBJECTIVE

The purpose of this prospective cohort study was to determine whether changes in cardiorespiratory fitness are associated with the metabolic response to endurance training in adolescents at risk of type 2 diabetes mellitus (T2DM).

METHODS

Seventy-three overweight and obese adolescents completed a 6-month endurance exercise intervention. Total fat mass, trunk fat mass, visceral adipose tissue, and liver fat were assessed with dual energy X-ray absorptiometry and magnetic resonance imaging spectroscopy.

RESULTS

The change in cardiorespiratory fitness with training was independently associated with reductions in BMI z-score (β = -0.09; P = 0.006), total fat mass (β = -1.40; P = 0.007), trunk fat mass (β = -0.70; P = 0.01), and liver fat (β = -1.80; P = 0.053). Adolescents within the highest tertile of change in fitness were 4.67 (95% CI: 1.15-13.73; P = 0.03), 11.90 (95% CI: 2.37-59.77; P = 0.002), and 6.21 (95% CI: 1.14-33.99; P = 0.035) times more likely to experience decreases in body weight, BMI, and liver fat compared with adolescents in the lowest tertile.

CONCLUSIONS

The changes in adiposity and hepatic triglyceride content in response to endurance training are significantly related to the increase in cardiorespiratory fitness in adolescents at risk of T2DM.

Glucose effectiveness in obese children: relation to degree of obesity and dysglycemia

OBJECTIVE

Impaired glucose effectiveness (GE) plays a role in the deterioration of glucose metabolism. Our aim was to validate a surrogate of GE derived from an oral glucose tolerance test (OGTT) and to assess the impact of degrees of obesity and of glucose tolerance on it.

RESEARCH DESIGN AND METHODS

The OGTT-derived surrogate of GE (oGE) was validated in obese adolescents who underwent an OGTT and an intravenous glucose tolerance test (IVGTT). We then evaluated anthropometric determinants of the oGE and its impact on the dynamics of glucose tolerance in a cohort of children with varying degrees of obesity.

RESULTS

The correlation of oGE and IVGTT-derived GE in 98 obese adolescents was r = 0.35 (P < 0.001) as a whole and r = 0.51 (P < 0.001) in subjects with normal glucose tolerance. In a cohort of 1,418 children, the adjusted GE was associated with increasing obesity (P < 0.001 for each category of obesity). Quartiles of oGE and the oral disposition index were associated with 2-h glucose levels (P < 0.001 for both). Among 421 nondiabetic obese subjects (276 subjects with normal glucose tolerance/145 subjects with impaired glucose tolerance who repeated their OGTT after a mean time of 28 ± 16 months), oGE changes were tightly associated with weight (r = 0.83, P < 0.001) and waist circumference changes (r = 0.67, P < 0.001). Baseline oGE and changes in oGE over time emerged as significant predictors of the change in 2-h glucose levels (standardized B = -0.76 and B = -0.98 respectively, P < 0.001 for both).

CONCLUSIONS

The oGE is associated with the degree of and changes in weight and waist circumference and is an independent predictor of glucose tolerance dynamics.