Distribution of fasting plasma insulin, free fatty acids, and glucose concentrations and of homeostasis model assessment of insulin resistance in a representative sample of Quebec children and adolescents

Fasting, post-OGTT challenge, and nocturnal free fatty acids in prediabetic versus normal glucose tolerant overweight and obese Latino adolescents

Type 2 diabetes risk and its relationship to free fatty acid (FFA) exposure and visceral fat by prediabetes status in minority adolescents have yet to be explored. Therefore, the objective of this study was to examine the association of circulating FFA under varying conditions with prediabetes in Latino adolescents and to determine the relative relationships of FFA and visceral adiposity to insulin sensitivity, secretion, and β-cell function. Overweight or obese, but otherwise healthy Latino adolescent males and females (n = 164, 14.2 ± 2.5 years), were recruited for assessment of prediabetes, abdominal fat, and FFA levels taken at a fasting state (FFAF), during an OGTT (FFAOGTT), and overnight (FFANOCTURNAL). Prediabetic adolescents had a higher FFAF than those with normal glucose tolerance when controlling for age, sex, pubertal status, total percent body fat, and visceral fat. FFAOGTT and FFANOCTURNAL did not differ between participants with prediabetes and those with normal glucose tolerance after adjusting for covariates. Visceral fat was independently related to insulin sensitivity and secretion in pubertal adolescents; however, in post-pubertal adolescents, FFAF and visceral fat were both independent and negatively related to β-cell function. These results support a plausible progression of the lipotoxicity theory of diabetes development during the pubertal transition.

High prevalence of prediabetes in a Swedish cohort of severely obese children

OBJECTIVE

In this cohort of severely obese children and adolescents in Sweden we investigate the prevalence of impaired fasting glucose (IFG), impaired glucose tolerance, (IGT) and silent type 2 diabetes (T2D), in relation to insulin resistance, insulin secretion, disposition index and cardio respiratory fitness.

METHODS

A total of 134 obese children and adolescents [57 females, 77 males, age 13.7 ± 2.7, body mass index (BMI) standard deviation score (SDS) 3.6 ± 0.6] consecutively referred to the National Childhood Obesity Centre performed an oral glucose tolerance test (OGTT), frequently sampled intravenous glucose tolerance test (fs-IVGTT), dual X-ray absorptiometry (DEXA), bicycle ergometer test and fasting levels of glucose, insulin and c-peptide were obtained and homeostatic model of insulin resistance (HOMA-IR) was calculated.

RESULTS

Isolated impaired fasting glucose (i-IFG) were present in 35.8 and 6% had isolated IGT. Combined IGT and IFG were present in 14.2%. The subjects with combined IGT/IFG had significantly lower acute insulin response (AIR) compared with subjects who had normal glucose metabolism or i-IFG (p < 0.05). Among the prepubertal children (n = 24), 25% (6/24) had i-IFG and 25% (6/24) had IGT/IFG and it was predominantly males. Disposition index was the major determinant of 2-h glucose levels (β = -0.49, p = 0.0126). No silent diabetes was detected.

CONCLUSION

In this cohort of severely obese children and adolescents the prevalence of prediabetes was very high. IFG was two times higher in this cohort of severely obese children than in a recently published unselected cohort of obese children in Sweden. In spite of the high prevalence of prediabetes, no subjects with silent diabetes were found.

Hepatocyte nuclear factor 4 alpha polymorphisms and the metabolic syndrome in French-Canadian youth

Objectives

Hepatocyte nuclear factor 4 alpha (HNF4α) is a transcription factor involved in the regulation of serum glucose and lipid levels. Several HNF4A gene variants have been associated with the risk of developing type 2 diabetes mellitus. However, no study has yet explored its association with insulin resistance and the cardiometabolic risk in children. We aimed to investigate the relationship between HNF4A genetic variants and the presence of metabolic syndrome (MetS) and metabolic parameters in a pediatric population.

Design and Methods

Our study included 1,749 French-Canadians aged 9, 13 and 16 years and evaluated 24 HNF4A polymorphisms that were previously identified by sequencing.

Results

Analyses revealed that, after correction for multiple testing, one SNP (rs736824; P<0.022) and two haplotypes (P1 promoter haplotype rs6130608-rs2425637; P<0.032 and intronic haplotype rs736824-rs745975-rs3212183; P<0.025) were associated with the risk of MetS. Additionally, a significant association was found between rs3212172 and apolipoprotein B levels (coefficient: -0.14 ± 0.05; P<0.022). These polymorphisms are located in HNF4A P1 promoter or in intronic regions.

Conclusions

Our study demonstrates that HNF4α genetic variants are associated with the MetS and metabolic parameters in French Canadian children and adolescents. This study, the first exploring the relation between HNF4A genetic variants and MetS and metabolic variables in a pediatric cohort, suggests that HNF4α could represent an early marker for the risk of developing type 2 diabetes mellitus.

Insulin and BMI as predictors of adult type 2 diabetes mellitus

BACKGROUND AND OBJECTIVES

Fasting insulin concentrations are increasingly being used as a surrogate for insulin resistance and risk for type 2 diabetes (T2DM), although associations with adult outcomes are unclear. Our objective was to determine whether fasting insulin concentrations in childhood associate with later T2DM.

METHODS

Fasting insulin values were available from 2478 participants in the longitudinal Cardiovascular Risk in Young Finns Study at baseline age 3 to 18 years, along with data on adult T2DM (N = 84, mean age = 39.6 years).

RESULTS

Among 3- to 6-year-olds, a 1-SD increase in fasting insulin was associated with a relative risk (RR) of 2.04 (95% confidence interval [CI], 1.54-2.70) for later T2DM, which remained significant after we adjusted for BMI and parental history of T2DM. For those aged 9 to 18 years, a 1-SD increase in insulin was associated with an RR of 1.32 (95% CI, 1.06-1.65) for T2DM, but this became nonsignificant after we adjusted for BMI and parental history of T2DM. In the latter age group, a 1-SD increase in BMI was associated with an RR of 1.45 (95% CI, 1.21-1.73) for T2DM, with adjustment for insulin and parental history of T2DM not improving this association. BMI in younger children was not associated with later T2DM. In life course analyses, those with T2DM had higher fasting insulin levels in early childhood and later adulthood but not in peripubertal years.

CONCLUSIONS

Elevated fasting insulin concentrations in early childhood, but not adolescence, are independently associated with an elevated risk of T2DM in adulthood.

Endocrine effects of valproic acid therapy in girls with epilepsy: a prospective study

BACKGROUND/AIM

It is controversial whether the endocrine dysfunction in epilepsy patients is caused by the epilepsy itself, the antiepileptic therapy, or both. We prospectively evaluated the long-term impact of valproic acid monotherapy compared to other anti-epileptic drugs on anthropometric, metabolic, hormonal, and ultrasonographic parameters in girls with epilepsy.

METHODS

Fifty-seven female patients with epilepsy who had started therapy at mean age of 11.5 ± 3.3 years, 42 with valproic acid (mean dose 13.1 ± 7.0 mg/kg/day and 15 with other anti-epileptic agents were followed for a mean of 3.2 years (range 1.0-8.5 years) in our center. Clinical, hormonal and transabdominal pelvic ultrasound data were collected at 3 time points: before and 6-12 months after onset of anti-epileptic drug treatment; and at the last visit while patients were still taking anti-epileptic drugs.

RESULTS

There were no significant between-group differences regarding changes in height, body mass index standard deviation score, levels of glucose and insulin, or lipid and endocrine profile from first to last visits. Mean thyroid-stimulating hormone level increased significantly between first and last visit only in the valproic acid group (p < 0.001), with no significant difference in free T4 level over time or between groups. The rate of clinical polycystic ovary syndrome for the valproic acid group (11%) was comparable to that reported in healthy controls (5-10%).

CONCLUSIONS

Administration of valproic acid had no adverse effect on body weight, metabolic status or endocrine function over an average follow-up of 3.2 years. Valproic acid appears to be safe for use in girls with epilepsy.

Plasma non-esterified fatty acid levels in children and their relationship with sex steroids

OBJECTIVE

Puberty is associated with decreased insulin sensitivity. Sexual hormones have been related with the onset of insulin resistance, but their relationship with non-esterified fatty acids (NEFA) remains unexplored. The aim of this study was to evaluate circulating NEFA levels in population-based samples of prepubertal children and adolescents and to analyze the association of NEFA with obesity, insulin resistance, and sexual hormones in adolescents.

EXPERIMENTAL

The studied population included 854 randomly selected 6-8-year-old children and 822 children aged 12-16years. NEFA levels were determined using a commercial kit. Testosterone and estradiol levels were determined by RIA, and insulin and sex hormone binding protein by IRMA. HOMA was calculated as an indicator of insulin resistance.

RESULTS

NEFA levels were lower in adolescents than in 6-8-year-old children, and decreased progressively with age between 12-year-olds and 16-year-olds. No significant differences in NEFA levels were observed between obese and non-obese adolescents. NEFA were not correlated with insulin or HOMA in 12-16-year-old girls, and appear negatively correlated with these variables in boys. Insulin and HOMA were negatively correlated with SHBG levels in both sexes adjusting by age but NEFA levels were not.

CONCLUSIONS

NEFA levels decrease with age in adolescents and are not significantly increased in obese children, supporting the fact that the decreased insulin sensitivity at this age is not affecting NEFA metabolism. Although SHBG is related to insulin and HOMA independently of age in both sexes, SHBG levels are not associated with NEFA.

Medical and non-medical complications among children and adolescents with excessive body weight

BACKGROUND

The burden of disease from childhood obesity is considerable worldwide, as it is associated with several co-morbidities, such as dyslipidemia, hypertension, type 2 diabetes (T2DM), orthopedic and psychosocial problems. We aimed at determining the prevalence of these complications in a population of children and adolescents with body weight excess.

METHODS

This is a cohort study including 774 new patients (1.7 - 17.9 yrs, mean 11.1 ± 3.0) attending a pediatric obesity care center. We assessed personal and family medical histories, physical examination, systemic blood pressure, biochemical screening tests.

RESULTS

We found that the great majority of the children suffered from at least one medical complication. Orthopedic pathologies were the most frequent (54%), followed by metabolic (42%) and cardiovascular disturbances (31%). However, non-medical conditions related to well-being, such as bullying, psychological complaints, shortness of breath or abnormal sleeping patterns, were present in the vast majority of the children (79.4%). Family history of dyslipidemia tends to correlate with the child's lipids disturbance (p = .053), and ischemic events or T2DM were correlated with cardiovascular risk factors present in the child (p = .046; p = .038, respectively).

CONCLUSIONS

The vast majority of obese children suffer from medical and non-medical co-morbidities which must be actively screened. A positive family history for cardiovascular diseases or T2DM should be warning signs to perform further complementary tests. Furthermore, well-being related-complaints should not be underestimated as they were extremely frequent.

Insulin resistance is not associated with thermogenic effect of a high-fat meal in obese children

In adults, insulin resistance may decrease the thermogenic effect of food, contributing to weight gain. We aimed to determine the effect of insulin resistance on energy expenditure in children with long-standing obesity. We hypothesized that thermogenic effect of food would decrease with increasing insulin resistance. Energy expenditure was measured using whole room indirect calorimetry in obese children 7 to 18 years old. Participants were fed a high-fat meal with energy content equal to 35% of measured resting energy expenditure. Thermogenic effect of food was measured for 180 minutes posttest meal and expressed as a percent of calories consumed. Body composition was assessed using whole-body dual-energy x-ray absorptiometry. Fasting glucose, insulin, and hemoglobin A1C were measured. Complete data were available for 25 children (median age, 12.1 years; 52% male). As expected, a significant decrease in resting energy expenditure was observed with increasing Tanner stage (P = .02 by Kruskal-Wallis test). Insulin sensitivity, as determined by homeostasis model assessment index equation, did not significantly affect resting energy expenditure (P = .3) or thermogenic effect of food (P = .7) after adjustment for Tanner stage. In conclusion, our study did not find an association between insulin resistance and energy expenditure in obese children.

Relationships between 24-hour urinary free cortisol concentrations and metabolic syndrome in obese children

CONTEXT

Clinical features of Metabolic Syndrome (MetS) and Cushing's Syndrome are similar, suggesting a pathogenetic role of hypothalamus-pituitary-adrenal axis in MetS.

OBJECTIVE

The aim of the study was to determine whether MetS diagnosis and specific clusters of MetS components (waist circumference, dyslipidemia, hypertension, and impaired glucose metabolism) are associated with serum cortisol (SC) or 24-h urinary free cortisol (UFC) levels.

DESIGN AND SETTING

We conducted cross-sectional analyses of data from our obesity cohort. We studied 264 obese children (age, 11.0 ± 2.8 years; male, 48%; BMI, 28.2 ± 5.4 kg/m(2)). We examined UFC, SC, homeostasis model assessment (HOMA), and features of MetS (waist circumference, blood pressure, fasting lipids, and glucose).

RESULTS

Slightly increased UFC concentrations were measured in 30.7% of the children. Obese children with MetS had significantly (P = .003) higher UFC levels compared with obese children without MetS. Girls demonstrated significantly higher UFC concentrations compared with boys independent of pubertal stage. UFC and SC levels were significantly related to features of MetS, but the associations were stronger for UFC. In multivariate analyses adjusted for age, sex, and body mass index, none of the features of MetS but HOMA index was correlated with UFC, whereas SC demonstrated no significant association to any parameter of MetS or HOMA.

CONCLUSIONS

Our findings support the hypothesis that changes in the hypothalamus-pituitary-adrenal axis are related to MetS in obesity. UFC seems to be a suitable marker for this relationship. Norm values for UFC adapted to obese children may help to avoid unnecessary dexamethasone suppression tests.

How to screen obese children at risk for type 2 diabetes mellitus?

BACKGROUND

Recommended screening to identify children at risk for diabetes and its precursors impaired glucose tolerance (IGT) and insulin resistance (IR) is fasted plasma glucose (FPG). This study evaluates the added value of fasted plasma insulin (FPI).

METHODS

This study analyzed routinely collected data of an oral glucose tolerance test (OGTT) of 311 obese children (age 10.8 ± 3.2 years). Diabetes and IGT were defined according to the American Diabetes Association criteria, IR as homeostasis model assessment (HOMA)-IR ≥3.4.

RESULTS

Cases diagnosed with an OGTT if FPG ≥5.6 mmol/L, compared with an OGTT performed if FPG ≥5.6 mmol/L or HOMA-IR ≥3.4, were, respectively, 4 (80%) versus 5 (100%) with diabetes, 7 (28%) versus 16 (64%) with IGT, and 0 (0%) versus 93 (100%) with IR.

CONCLUSIONS

Screening with FPG and FPI has equal burden compared with screening with FPG alone, identifies all patients with diabetes, and identifies more patients with precursors of diabetes.

Circulating undercarboxylated osteocalcin and gingival crevicular fluid tumour necrosis factor-α in children

BACKGROUND

Osteocalcin, a protein secreted by osteoblasts during bone formation, is negatively associated with adult periodontal disease. Little is known about this association in children.

AIM

To examine the extent to which plasma undercarboxylated osteocalcin (ucOC) is associated with gingival crevicular fluid tumour necrosis factor-alpha (GCF TNF-α) - a potential marker of gingival inflammation - in children.

METHODS

We used data from the Quebec Adipose and Lifestyle InvesTigation in Youth cohort, an ongoing longitudinal study on the natural history of obesity among Caucasian children with a family history of obesity in Quebec, Canada. This cross-sectional analysis from the baseline visit includes 120 children aged 8-10 years. Plasma ucOC and GCF TNF-α levels were determined by enzyme-linked immunosorbent assay. Linear regression analyses, adjusting for age, gender, family income, sexual maturity stage, daily physical activity, obesity, and fasting glucose were conducted, with TNF-α level as the dependent variable.

RESULTS

A 1-ng/ml increase in ucOC was associated with a 0.96% decrease (95% confidence interval (CI): -1.69, -0.23) in GCF TNF-α level.

CONCLUSION

A negative association between a marker of bone formation and a marker of gingival inflammation was observed as early as childhood among Caucasian children with a family history of obesity.

Insulin secretion and its association with physical activity, fitness and screen time in children

OBJECTIVES

To determine the independent associations of moderate to vigorous physical activity (MVPA), fitness, screen time, and adiposity with insulin secretion in children.

DESIGN AND METHODS

Caucasian youth (n = 423/630), 8-10 years old, with at least one obese biological parent, were studied (QUALITY cohort). Insulin secretion was measured using HOMA2-%B, area under the curve (AUC) of insulin to glucose over the first 30 minutes (AUC I/G(t30min)) of the OGTT and AUC I/G(t120min) over 2 hours. Fitness was measured by VO₂peak ; percent fat mass (PFM) by DXA; 7-day MVPA by accelerometry; self-reported screen time included television, video game, or computer use. Models were adjusted for age, sex, season, puberty, PFM, and insulin sensitivity [IS] (HOMA2-IS, Matsuda-ISI).

RESULTS

PFM was strongly associated with insulin secretion, even after adjustment for IS: for every 1% increase in PFM, insulin secretion increased from 0.3% to 0.8% across indices. MVPA was negatively associated with HOMA2-%B (P < 0.05), but not with OGTT-derived measures. Fitness was negatively associated with AUC I/G(t120min) (P < 0.05). Screen time showed a trend toward higher HOMA2-%B in girls (P = 0.060).

CONCLUSIONS

In children with an obese parent, lower insulin secretion is associated with lower adiposity, higher MVPA, better fitness, and possibly reduced screen time.

Prevalence of insulin resistance and cardiometabolic risk in Korean children and adolescents: a population-based study

AIMS

We aimed to establish normal reference values of serum insulin and the homeostasis model assessment of insulin resistance (HOMA-IR). We also aimed to verify HOMA-IR "cut-off values" in predicting cardiometabolic risk among Korean children and adolescents.

METHODS

Data from 2716 Korean subjects (1421 male and 1295 female, aged 10-20 years) were evaluated. Insulin resistance was defined as HOMA-IR >95th percentile. The odds ratios of cardiometabolic risk were assessed based on the state of insulin resistance.

RESULTS

Reference values of insulin and HOMA-IR were determined according to sex and age, based on data obtained from normal-weight subjects with normal fasting glucose levels. HOMA-IR values appeared to peak at the age of 14-15 years in male subjects and at the age of 12-13 years in female subjects. The prevalence of insulin resistance in the subjects was 9.8% (male=10.9%, female=8.6%). The prevalence of insulin resistance in normal-weight, overweight, and obese subjects were 4.7%, 25.6%, and 47.1% respectively. Subjects with insulin resistance had a higher prevalence of metabolic syndrome (odds ratios=18.33; 95% confidence interval, 9.62-34.94) and its components, especially hyperglycemia and hypertriglyceridemia.

CONCLUSION

We established reference values of serum insulin and HOMA-IR according to age and sex. Obesity is the most important risk factor for insulin resistance and metabolic syndrome. However, insulin resistance independently increases cardiometabolic risk. This information may be useful for Korean as well as other Asian in planning programs for the prevention of type 2 diabetes.

Dietary composition and its associations with insulin sensitivity and insulin secretion in youth

The objectives of the present study were to examine the associations between macronutrient intake and insulin sensitivity (IS) and insulin secretion (ISct), taking into consideration moderate-to-vigorous physical activity (MVPA), fitness and sedentary behaviour. Caucasian youth (n630) aged 8–10 years at recruitment, with at least one obese biological parent, were studied (QUebec Adipose and Lifestyle InvesTigation in Youth cohort). IS was measured using the homeostasis model assessment (HOMA) of insulin resistance and Matsuda IS index. ISct was measured using HOMA2 %-β, the ratio of the AUC of insulin:glucose over the first 30 min (AUC I/Gt= 30min) of the oral glucose tolerance test and AUC I/Gt= 120minover 2 h. Fitness was measured using VO2peak, percentage of fat mass by dual-energy X-ray absorptiometry, and 7 d MVPA using accelerometry; screen time (ST) by average daily hours of self-reported television, video game or computer use. Dietary composition was measured using three non-consecutive dietary recalls. Non-parametric smoothing splines were used to model non-linear associations; all models were adjusted for age, sex, season, pubertal stage, MVPA, fitness, ST and adiposity. The percentage of total daily energy from dietary protein, fat, saturated fat and carbohydrate and the consumption of dietary vitamin D, sugar-sweetened beverages, fibre and portions of fruits and vegetables were taken into consideration. No dietary component was associated with any measure of IS after adjusting for MVPA, fitness, ST and adiposity. For every 1 % increase in daily protein intake (%), AUC I/Gt= 30mindecreased by 1·1 % (P= 0·033). Otherwise, dietary composition was not associated with ISct. While long-term excess of energy intake has been shown to lead to overweight and obesity, dietary macronutrient composition is not independently correlated with IS or ISct in youth.

Relation between serum free fatty acids and adiposity, insulin resistance, and cardiovascular risk factors from adolescence to adulthood

The objective of this study was to describe longitudinal relations of serum total free fatty acids (FFAs) to insulin resistance (IR) and cardiovascular (CV) risk factors from adolescence into adulthood. The cohort included participants in a longitudinal study of obesity and IR with complete data, including anthropometric measures, FFAs, IR measured by euglycemic clamp, blood pressure, fasting serum lipids, and insulin at mean 15 and 22 years of age (n = 207) and their parents (n = 272). FFAs and IR were not significantly related at mean 15 years of age but were significantly related at mean age 22 years. FFA did not relate to BMI at either age. FFA at 15 years of age estimated IR at 22 years of age. In parents (mean age 51 years), FFA was significantly correlated with BMI, percent body fat, systolic blood pressure, LDL, and IR. Associations with all risk factors except IR in parents were attenuated by adjustment for BMI. Most 22 years of age correlations with parents were higher than corresponding 15 years of age correlations. This study finds that FFA is associated with IR starting in young adulthood. The relation between FFA and CV risk factors does not become significant until later adulthood. The results support a significant impact of early metabolic dysfunction on later CV risk.

Calculating cardiac risk in obese adolescents before and after onset of lifestyle intervention

Prevalence and severity of obesity in adolescents is increasing worldwide. The obesity-associated cardiovascular risk factors (CRF) determine cardiac risk as demonstrated by longitudinal studies. Fat distribution and not overall fat mass determines the cardiac risk, since intra-abdominal adipose tissue is especially related to CRFs. Besides classical CRFs such as hypertension, dyslipidemia and impaired glucose metabolism, a proinflammatory and prothrombotic state in obesity is associated with cardiac risk. Adipocytokines such as adiponectin are related to cardiac risk and may present useful predictors of cardiac mortalities in future. Measurement of the carotid intima-media thickness is a new promising noninvasive marker for early cardiovascular changes including atherosclerosis. The therapy of choice to prevent cardiac events in obesity is lifestyle intervention of obese adolescents. However, in clinical practice, the weight loss in lifestyle interventions is only moderate and drug treatment of CRFs is seldom performed.

Relationship between carotid intima-media thickness and metabolic syndrome in adolescents

OBJECTIVE

To test the hypothesis that metabolic syndrome (MetS) is more predictive of carotid intima-media thickness (IMT) than the sum of the individual components of MetS.

STUDY DESIGN

We analyzed the relationships between 2 definitions of the MetS and IMT in 461 overweight adolescents aged 10-18 years (median body mass index, 28.6 kg/m(2)). We used regression models and receiver operating characteristics (ROCs) for increased IMT (defined as ≥0.7 mm).

RESULTS

The prevalence of MetS was 15.0% and 26.9% according to the 2 definitions applied. At the group level, quantitative IMT was associated with body mass index, blood pressure, glucose levels at 2 hours in an oral glucose tolerance test, and with each of the MetS components (all P < .05). At an individual level, using the MetS definitions alone as a diagnostic test for the presence of increased IMT (area under the ROC curve, 0.60-0.66) was inferior when compared with the sum of all individual components (area under the ROC curve, 0.65-0.85). Adding the presence or absence of MetS to the components did not improve the accuracy.

CONCLUSION

Overweight adolescents with MetS demonstrated increased IMT values compared with overweight adolescents without MetS. The best model for diagnosing increased IMT was the sum of the quantitative components of MetS. The use of dichotomized variables reduced the diagnostic accuracy. Thus, in clinical practice, treatment of overweight adolescents should be based on weighing cardiovascular risk factors themselves, rather than on the dichotomous variable MetS.

Continuous glucose monitoring system (CGMS) in kidney-transplanted children

NODAT and IGT are well-known complications of immunosuppressive therapy after transplantation being a risk factor for cardiovascular disease affecting patient and graft survival. Therefore, early identification and treatment are of high importance. In this study, we examined the glycemic homeostasis of 20 renal-transplanted children using routine laboratory tests and the continuous glucose monitoring system (CGMS). Six patients (30%) had IGT, and one patient had NODAT (5%). The HOMA index was in an abnormal range in 35% of all patients and was abnormal in 67% of the IGT patients. CGMS analysis showed that IGT patients had higher "lowest glucose" level, and the incidence of hypoglycemic episodes was significantly lower compared with patients with normal OGTT result. In IGT patients, glucose variability tended to be lower. Furthermore, in the whole patient cohort, glucose variability significantly decreased with time after transplantation. Summarizing, these novel data show that "lowest glucose" level and hypoglycemic episodes are significantly influenced and altered in renal-transplanted patients with IGT. Furthermore, there is a decrease in glucose variability with time after transplantation. The mechanism and relevance of these data need further investigations.

Regional distribution and metabolic effect of PCSK9 insLEU and R46L gene mutations and apoE genotype

BACKGROUND

Natural loss-of-function mutations in the proprotein convertase subtilisin/kexin type-9 gene (PCSK9) are associated with lower cholesterol and cardiovascular risk. Because a founder effect exists in French Canadians for many lipid-related genes, we sought to investigate PCSK9 mutations and associated variables in this population. We also investigated the combined effect of PCSK9 mutations and the apolipoprotein E (apoE) polymorphism on metabolic variables.

METHODS

Gene sequencing and screening was carried out in 1745 healthy individuals ages 9, 13, and 16 years from a provincially representative population sample. In parallel, we measured related metabolic markers and used appropriate statistical methods.

RESULTS

We report herein that the carrier rates of the R46L single-nucleotide polymorphism were higher in the French Canadian population (4.8%) than previously seen in Caucasian individuals (2.4%). This is second to the most common variant, insertion of leucine, at a carrier rate of 24%, making it the most common PCSK9 loss-of-function mutation in French Canadian individuals. In R46L carriers, the contribution of the apoE genotype better explains the cholesterol phenotype than the R46L mutation alone. Patients, with both the R46L and apoE3/E2 genotype also showed a tendency toward insulin resistance as indicated by a 2-fold increase in insulin, homeostasis model assessment of insulin resistance, and leptin concentrations, compared with those without apoE3/E2.

CONCLUSIONS

R46L and insertion of leucine mutations were more frequent in French Canadian individuals and showed a specific geographic distribution. This might represent a gene selection to overcome clustering genes harbouring familial hypercholesterolemia and might suggest a founder effect. Subjects with the apoE3/E2 genotype and R46L have increased plasma insulin, homeostasis model assessment of insulin resistance, and leptin, an intriguing finding that warrants further investigation.

Ghrelin-leptin network influences serum chitinase 3-like protein 1 (YKL-40) levels in obese prepubertal children

OBJECTIVE

This study aimed to investigate any possible interactions between hormonal regulators of weight gain and markers of subclinical inflammation in childhood obesity. Forty-one obese prepubertal children and 41 age- and gender-matched lean controls were included. Children were classified as obese or non-obese according to international age- and gender-specific body mass index (BMI) cutoff points defined by the International Obesity Task Force to define childhood obesity. Anthropometric measurements, serum insulin, chitinase 3-like protein (YKL-40), ghrelin and leptin levels as well as plasma glucose in the fasting state were determined.

RESULTS

Obese children as compared with controls had higher YKL-40 (50.7±15.2 vs 41.0±10.5 ng/ml, p=0.003), higher leptin (33.8±16.0 vs 9.7±7.5 ng/ml, p<0.001) and lower ghrelin serum levels (871.4±368.0 vs 1417.6±387.3 pg/ml, p<0.001). The obese children with ghrelin levels above median (43.8±10.2 ng/ml) as compared to those with ghrelin below median (57.2±16.6 ng/ml) presented lower serum YKL-40 levels (p=0.009), indicating more severe inflammation with lower levels of ghrelin. By contrast, although the obese children with leptin levels above median (49.7±16.3 ng/ml) presented lower serum YKL-40 levels as compared to those with leptin levels below median (51.6±14.6 ng/ml), this difference did not reach the level of statistical significance (p=0.726). Moreover, serum YKL-40 levels were significantly correlated with ghrelin (r=-0.359, p=0.014) but not with leptin levels (r=0.169, p=0.261). A significant negative correlation between ghrelin and leptin levels was also found (r=-0.276, p=0.041). These findings remained unchanged for obese, when analyses were done separately, whereas the significance of correlations was lost for non-obese subjects.

CONCLUSIONS

Ghrelin-leptin network had an impact on serum YKL-40 levels in obese prepubertal children; upregulation of YKL-40 secretion seems to be a consequence of reduced ghrelin rather than elevated leptin concentrations.

Development of hyperglycemia and diabetes in captive Polish bank voles

Diabetes has been detected in Danish and Swedish bank voles (Myodes glareolus). There are no data, however, concerning the prevalence of diabetes in populations from other geographic regions. We investigated the frequency and physiological effects of glucose metabolism disorders in captive bank voles from Poland. Single measurement of fasting blood glucose concentration performed in the 3-4month old captive-born bank Polish voles without any disease symptoms showed that 8% of individuals (22/284) displayed an impaired fasting glucose (IFG, blood glucose (BG) ≥100mg/dL) and 1% (4/284) showed hyperglycemia (BG ≥126mg/dL) which could suggest diabetes. Next, we analyzed blood glucose in samples taken once a month from an additional cohort of bank voles with (FHD), or without (H), a family history of diabetes. The prevalence of IFG at age six months was 26% (16/62) among bank voles from the H group. In the FHD group the prevalence increased to 49% (43/88), and additional 12% (11/88) became diabetic (DB, BG ≥126mg/dL at two time points). Postnatal stress (three maternal deprivations before weaning) did not affect the risk of developing IFG or DB in H voles, but significantly reduced the frequency of glucose metabolism disorders (IFG and DB combined) in FHD voles. IFG was associated with hyperinsulinemia, but not with other biochemical disturbances. Diabetic animals displayed a progressive malformation and vacuolization of β-cells in the pancreas, without visible leukocytic infiltrations. In summary, our results indicate that Polish captive bank voles can develop diabetes, which shows features of both type 1 and type 2 diabetes in humans. Risk of diabetes is higher in animal with FHD.

Effect of glutamine on glucose metabolism in children with Duchenne muscular dystrophy

BACKGROUND & AIMS

Glutamine is a potent gluconeogenic precursor and stimulates insulin secretion. Glutamine's effect on glucose metabolism in Duchenne muscular dystrophy (DMD) has never been studied. To determine plasma glucose and insulin concentrations measured during and after glutamine administration in DMD boys. We hypothesized that glutamine can modulate whole body glutamine-glucose metabolism in DMD, a genetically determined disease.

METHODS

As secondary endpoints of a randomized crossover trial in 30 prepubertal DMD boys, we measured fasting blood glucose, insulin and the Homeostasis Model Assessment (HOMA) index after daily oral glutamine (0.5 g kg(-1) d(-1)) for 4 months versus placebo. In a separate time series trial in 6 prepubertal DMD boys, we measured the same endpoints as well as plasma glutamine and whole body glucose turnover (Ra,glc) (primed continuous i.v. infusion of d-[6,6-(2)D]glucose), while participants received acute oral glutamine (0.5 g kg(-1) d(-1)) continuously for 5 h.

RESULTS

In the randomized trial, baseline measurements of HOMA correlated with age (r = 0,51, p = 0.007) and percent fat estimated by bioelectrical impedance analysis (BIA) (r = 0.39, p = 0.047). After 4 months glutamine supplementation, we observed no treatment or order effect on HOMA or insulin. During acute glutamine for 5 h (time series trial), plasma glutamine doubled and was associated with increased plasma insulin concentration (10.42 ± 2.54 vs 7.32 ± 1.86, p = 0.05) with no effect on plasma glucose, HOMA or Ra,glc.

CONCLUSIONS

Acute glutamine transiently stimulates insulin secretion in DMD boys, which could be mediated by plasma glutamine concentrations. Fasting insulin concentration and HOMA might provide quantifiable indices of disease progression.

Obesity in Spanish Schoolchildren: Relationship with Lipid Profile and Insulin Resistance

This article reports cross-sectional data from a total of 1048 children, 6 to 8 years of age, categorized by presence or absence of obesity, who participated in a voluntary survey of cardiovascular risk factors in Spain over the period of 1998 to 2000, to establish the relationship between obesity and its metabolic consequences at this age. The prevalence of obesity and overweight were 9.4% and 15.7%, respectively, in boys and 10.5% and 18.0%, respectively, in girls. We observed that, in both sexes, obese children had higher triglycerides and lower high-density lipoprotein-cholesterol levels than non-obese children. No differences were found in plasma glucose or low-density lipoprotein-cholesterol levels between normal and obese children. However, we observed that insulin levels and the homeostasis model assessment for insulin resistance were significantly (p<0.001) higher in obese children of both sexes but that free fatty acid levels were lower in obese children than in nonobese children, with a statistical significance in girls (0.72+/-0.30 vs. 0.61+/-0.16 mEq/liter). In summary, our survey found some metabolic consequences of obesity similar to those found in adults (elevated triglycerides, insulin, and the homeostasis model assessment for insulin resistance, and lower high-density lipoprotein-cholesterol). However, other features (glucose, total cholesterol, low-density lipoprotein-cholesterol, and free fatty acid levels) were found to behave differently, indicating that the association of obesity with risk factors seems to change as the children age and may depend on the chronology of sexual maturation.

How are physical activity, fitness, and sedentary behavior associated with insulin sensitivity in children?

OBJECTIVE

To describe the associations among moderate-to-vigorous physical activity (MVPA), fitness, sedentary behavior (SB), and insulin sensitivity (IS).

RESEARCH DESIGN AND METHODS

Data were drawn from the baseline assessment of the QUALITY cohort, which included 630 white youth (aged 8-10 years at recruitment), with at least one obese biological parent. IS was measured by two fasting indices (insulin, homeostasis model assessment of insulin resistance) and an oral glucose tolerance test (OGTT)-based index (Matsuda IS index [Matsuda-ISI]). Fitness was measured by Vo(2peak); percent fat mass (PFM) was measured by dual-energy X-ray absorptiometry; 7-day MVPA was measured with accelerometry. SB indicators included average hours daily of self-report screen time (SBst), and average minutes daily at <100 counts/min from accelerometry (SBacc). Multivariable linear regression models were adjusted for age, sex, season, and puberty.

RESULTS

MVPA and SBacc were independently associated with IS, but this was no longer statistically significant after accounting for PFM. SBst was negatively associated with IS in girls only, even after controlling for physical activity (PA), fitness, and adiposity; for each additional hour of SBst daily, IS decreased by 4.6-5.6% across all IS indices. Fitness was positively associated with IS (measured by Matsuda-ISI) after accounting for PA, SB, and PFM; for every 1 unit increase in Vo(2peak), Matsuda-ISI increased by approximately 1.0% (P < 0.05).

CONCLUSIONS

In children with an obese parent, PA and SBacc are associated with IS, but this association is mediated by adiposity. SBst is negatively associated with IS in girls, beyond its known impact on adiposity. Finally, fitness is independently associated with better IS measured by OGTT.

Increased pancreatic fat fraction is present in obese adolescents with metabolic syndrome

OBJECTIVES

Little is known about pancreatic fat accumulation and its possible associations with metabolic syndrome (MetS) and glucose metabolism. The aim of the present study was to quantify pancreatic fat fraction (PFF) in lean and obese adolescents and explore its relation to metabolic parameters.

METHODS

We recruited 25 lean and 24 obese adolescents. PFF and visceral adipose tissue (VAT) were determined using magnetic resonance imaging. We measured blood pressure, fasting glucose, insulin, liver enzymes, leptin, and lipid levels. Obese subjects underwent an oral glucose tolerance test.

RESULTS

PFF was significantly higher in obese than in lean subjects (4.8±1.2 vs 3.6±0.9; P<0.001) and was associated with VAT, γ-glutamyltransferase, triglycerides, high-density lipoprotein cholesterol, leptin concentrations, and MetS (P<0.05 for all). None of the obese subjects had glucose intolerance, but when adjusted for VAT, the following 3 parameters correlated negatively with PFF: fasting and 30- minute and 120-minute insulin levels. We divided subjects into 3 groups: group I, lean without MetS; group II, obese without MetS; and group III, obese with MetS, and observed that PFF increased gradually among groups (I: 3.56%±0.88%; II: 4.70%±1.06%; III: 5.34%±1.49%; P<0.001).

CONCLUSIONS

Obese adolescents accumulate fat in the pancreas. PFF correlates with the presence of MetS. Even in the absence of glucose intolerance, pancreatic fat deposition is associated with impaired insulin response to glucose overload. This suggests that β-cell dysfunction may already be present in nondiabetic obese adolescents, mirroring what has been shown in adults, and that pancreatic fat accumulation may participate in obesity-associated pancreatic endocrine dysfunction.

Novel modeling of reference values of cardiovascular risk factors in children aged 7 to 20 years

BACKGROUND AND OBJECTIVE

Most of the cardiovascular risk factors strongly associated with obesity and overweight vary with age and gender. However, few reference values are available for healthy European children. Our objective was to establish pediatric reference ranges for waist circumference, systolic and diastolic blood pressures, fasting lipid levels (total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides), glucose, and insulin.

METHODS

A representative sample of 1976 healthy French individuals (1004 female participants and 972 male participants) aged 7 to 20 years was used to obtain age- and gender-specific normal ranges for each of the above-listed cardiovascular risk factors, based on the Royston and Wright method.

RESULTS

Mean waist circumference increased with age in both genders and was slightly higher in males than in females. Whereas systolic blood pressure increased gradually with age, with the increase being steeper in males than in females, no gender effect was found for diastolic blood pressure, which was therefore modeled after pooling males and females. Total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglyceride values varied little with age and gender. Glucose and insulin levels revealed pubertal peaks, which were sharper in females than in males, reflecting the normal insulin resistance during puberty.

CONCLUSIONS

These ranges can be used as references for European children to monitor cardiovascular risk factors and to plan interventions and education programs.

Elevated circulating levels of the serum acute-phase protein YKL-40 (chitinase 3-like protein 1) are a marker of obesity and insulin resistance in prepubertal children

YKL-40 (chitinase 3-like protein 1) is a newly recognized protein that is secreted by activated macrophages and neutrophils and expressed in a broad spectrum of inflammatory conditions and cancers. It has also been associated with endothelial dysfunction and diabetes in adults. Its role in childhood obesity has not been evaluated yet. Our aim was to evaluate the associations of serum YKL-40 levels with markers of obesity, inflammation, and insulin resistance in children. Forty-one obese prepubertal children and 41 age- and sex-matched lean controls were included, and serum YKL-40 levels were determined. Body mass index (BMI), blood pressure (BP), body fat percentage, fasting glucose, insulin, homeostasis model assessment for insulin resistance (HOMA-IR) index, whole-body insulin sensitivity index, lipids, white blood cell (WBC) count, C-reactive protein, and fibrinogen levels were also assessed. Obese children had higher YKL-40 levels compared with controls (P = .003). Insulin-resistant individuals showed higher YKL-40 compared with non-insulin-resistant individuals after adjusting for age and BMI (adjusted P = .039). Serum YKL-40 levels were positively correlated with age, BMI, body fat percentage, fasting glucose and insulin, HOMA-IR index, whole-body insulin sensitivity index, systolic BP, mean BP, and WBC count (P < .05). After adjustment for age, sex, BMI, WBC count, and systolic BP, HOMA-IR index remained significantly associated with YKL-40 levels (P < .001). The study suggests that YKL-40 levels are elevated in obese youth and represent a marker of insulin resistance even in childhood. Prospective studies are needed to determine whether children with elevated YKL-40 levels are at higher risk for future cardiovascular disease.

Related factors of insulin resistance in Korean children: adiposity and maternal insulin resistance

Increased adiposity and unhealthy lifestyle augment the risk for type 2 diabetes in children with familial predisposition. Insulin resistance (IR) is an excellent clinical marker for identifying children at high risk for type 2 diabetes. This study was conducted to investigate parental, physiological, behavioral and socio-economic factors related to IR in Korean children. This study is a cross-sectional study using data from 111 children aged 7 years and their parents. Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated using fasting glucose and insulin level as a marker of IR. All children’s adiposity indices (r = 0.309–0.318, all P-value = 0.001) and maternal levels of fasting insulin (r = 0.285, P-value = 0.003) and HOMA-IR (r = 0.290, P-value = 0.002) were positively correlated with children’s HOMA-IR level. There was no statistical difference of children’s HOMA-IR level according to children’s lifestyle habits and socioeconomic status of families. An increase of 1 percentage point in body fat was related to 2.7% increase in children’s HOMA-IR (P-value < 0.001) and an increase of 1% of maternal level of HOMA-IR was related to 0.2% increase in children’s HOMA-IR (P-value = 0.002). This study shows that children’s adiposity and maternal IR are positively associated with children’s IR.

Distribution of the homeostasis model assessment of insulin resistance in Mexican children and adolescents

OBJECTIVE

Several cutoff points of the homeostasis model assessment of insulin resistance (HOMA-IR; varying from 2.5 to 4.0) have been suggested for diagnosing IR in youth. In this study, we determined the distribution of the HOMA-IR in Mexican children and adolescents.

DESIGN AND METHODS

A total of 6132 children and adolescents from San Luis Potosi, León, Queretaro, and Durango, which are cities in central and northern Mexico, were enrolled in a population-based cross-sectional study. Eligible participants were apparently healthy children and adolescents aged 6-18 years. Pregnancy and the presence of chronic illnesses were exclusion criteria.

RESULTS

A total of 3701 (60.3%) girls and 2431 (39.7%) boys were included in this study. In the overall population, the mean body mass index, insulin levels, and fasting glucose levels were 21.8±1.3 kg/m(2), 7.1±3.2 μU/ml, and 86.2±10.0 mg/dl respectively. The concentrations of insulin and fasting glucose gradually increased from 6 to 12 years of age, whereas the concentrations tended to plateau in the 13- to 18-year-old population. The absolute mean of the HOMA-IR was 2.89±0.7. The HOMA-IR gradually increased with age and reached a plateau at 13 years of age.

CONCLUSIONS

Because the insulin concentrations, glucose levels, and HOMA-IR exhibited a gradual increase with age that was not related to obesity, our results suggested that the evaluation of IR in children should be based on percentiles of the HOMA-IR rather than a dichotomous value derived from a single cutoff point.

Long-term effect of lifestyle intervention on adiposity, metabolic parameters, inflammation and physical fitness in obese children: a randomized controlled trial

Background:

Behavioral lifestyle intervention, combined with parental involvement, is preferred over standard care or self-help in childhood obesity. The short-term results of such interventions are promising, but long-term follow-up results are equivocal.

Objective:

The objective of the present study was the short (3 months) and long-term (1 and 2 years follow-up) effect evaluation of a family-based multidisciplinary cognitive behavioral lifestyle intervention on markers of adiposity, metabolism, inflammation and physical fitness compared with standard care in children with obesity. Also the association between these outcome variables was determined.

Methods:

In this prospective longitudinal clinical trial, obese children were randomly assigned to a 3-month family-based cognitive behavioral multidisciplinary lifestyle treatment (n=40; body mass index-standard deviation score (BMI-SDS) 4.2±0.7; age; 13.3±2.0 years) or to a control group receiving an initial advice on physical activity and nutrition (n=39; BMI-SDS 4.3±0.6; age 13.1±1.9 years). Anthropometric data, physical fitness, metabolic parameters and inflammatory state were evaluated at baseline, after intervention (at 3 months) and at 1-year follow-up. At 2-year follow-up, anthropometric data and physical fitness were measured in the intervention group.

Results:

An intervention effect after 1 year was found for adiposity (P=0.02 for BMI-SDS, P=0.03 for waist circumference (WC)-SDS), physical fitness (absolute measured peak value of oxygen uptake (ml min⁻¹), standardized for age and gender (VO_2peak-SDS), P<0.01) and insulin resistance (HOMA-SDS, P=0.04). No significant intervention effect was found for serum lipid profile, high-sensitive C-reactive protein or for adiponectin. At 2-year follow-up, BMI-SDS in the intervention group (n=31) was 3.8±1.2 SDS, significantly less than at baseline (P=0.02).

Conclusion:

A positive 1-year follow-up treatment effect was found for adiposity, physical fitness and glucose homeostasis, but not for inflammatory markers. There was a significant long-term treatment effect on adiposity, although almost all children remained obese.

Proinsulin and the proinsulin/insulin ratio in overweight and obese children and adolescents: relation to clinical parameters, insulin resistance, and impaired glucose regulation

BACKGROUND

In adults with impaired glucose regulation (IGR) or type 2 diabetes mellitus (T2DM), proinsulin (PI) and its ratio to insulin (ins; PI/I ratio) are frequently elevated.

OBJECTIVE

Here we assessed the relationship among fasting PI, clinical parameters, and carbohydrate metabolism, a potential difference of the PI/I ratio between overweight and obese youth with or without IGR in an oral glucose tolerance test (OGTT) and the predictive power of PI levels for IGR.

DESIGN AND PATIENTS

In a cross-sectional study, data of n = 259 children and adolescents attending our obesity clinic were studied.

METHODS

Fasting PI levels were determined in all patients and matched to the standard assessment of obesity. In n = 154 subjects at risk for T2DM, an OGTT was performed sampling for glucose, ins, and PI.

MAIN OUTCOME MEASURES

ins, glucose, PI, PI/I ratio, insulin resistance [homeostasis model assessment of insulin resistance index (HOMA-IR)].

RESULTS

Puberty (by Tanner) and relative body weight [body mass index (BMI)-standard deviation of BMI (SDS)] showed a linear relationship to fasting PI levels (p < 0.001 for Tanner I vs. II-V; p = 0.04 and p = 0.026 for BMI-SDS < 2 vs. 2-2.5 and 2-2.5 vs. > 2.5, respectively). Subjects with ins resistance (HOMA-IR > 95th percentile, n = 140) had higher fasting PI levels than those without (p < 0.001), with no significant difference in fasting PI/I ratio (p > 0.05). As compared to subjects with normal glucose regulation, subjects with IGR (n = 35) had higher fasting PI (p = 0.001) and an increased PI/I ratio, both during fasting and at 30 min during OGTT (p = 0.049 and p = 0.014, respectively).

CONCLUSIONS

Children and adolescents with IGR have disproportionately elevated PI levels, both during fasting and after acute glucose stimulation indicating β-cell dysfunction.

Changes in adipose-derived inflammatory cytokines and chemokines after successful lifestyle intervention in obese children

Obesity has been associated with low-grade chronic systemic inflammation, potentially leading to insulin resistance. This study was designed to examine relationships between cardiovascular risk factors, insulin resistance, and simultaneously measured inflammatory parameters in obese children. We examined serum inflammatory parameters in 115 obese children and 30 normal-weight controls; 62 obese children were followed longitudinally in a 1-year obesity intervention study. Serum concentrations of adipose tissue hormones adiponectin and resistin as well as adipocytokines were assessed. Cross-sectional analysis showed significant correlations between standard deviation score body mass index and resistin (P = .0004) as well as monocyte chemoattractant protein-1 (MCP-1, P = .04). Increased homeostasis model assessment of insulin resistance index greater than 95th percentile was present in 32% of obese patients, correlating with adiponectin (r = -0.40, P = .0007). Significant correlations were found between adiponectin and several mediators of inflammation (interleukins [ILs] IL-1β, IL-6, and IL-8 and tumor necrosis factor-α). In longitudinal analysis, substantial weight loss (change standard deviation score body mass index >0.5) observed after intervention in 29 children was associated with a significant decrease in blood pressure, homeostasis model assessment of insulin resistance index, and serum concentrations of insulin and IL-1β, IL-8, and MCP-1, but increase of adiponectin (all Ps < .05). In 33 children without substantial weight loss, resistin and MCP-1 levels increased after 1 year. Changes in IL-1β correlated positively with changes of weight status, interferon-γ, IL-6, IL-8, and tumor necrosis factor-α (all Ps < .01). Our study demonstrates significant correlations between different metabolic risk factors at baseline and after changes of weight status and that weight loss in obese children reduces low-grade inflammation, insulin resistance, and blood pressure.

Ethnicity and comorbidities in an overweight and obese multiethnic childhood cohort in Berlin

AIM

This study aims to analyse the association between ethnicity, elevated metabolic parameters and metabolic syndrome (MS) in a multiethnic cohort of overweight to obese children and adolescents.

METHODS

For 1053 patients, standard deviation of body mass index (BMI-SDS) was calculated and metabolic parameters (fasting blood glucose, fasting insulin, homeostasis model assessment-IR, lipids, blood pressure) were measured. MS was defined by WHO criteria. Bivariate and multivariate analyses were performed. Adjusted differences in BMI-SDS and metabolic parameters between different migration groups were assessed with linear regression models. The risk for MS was calculated with multiple logistic regression models.

RESULTS

Forty-eight per cent of the children were German, 25% Turkish and 27% had another ethnicity. Concerning weight status, 23% are overweight, 31% obese and 46% extremely obese with higher rates among the immigrant population. Multivariable models indicate significant associations between elevated metabolic parameters and higher BMI-SDS values. Overall prevalence of MS was 32.3%. MS was detected significantly more often among Turkish patients (40.4%) compared to Germans (27.3%; p=0.02). Logistic regression analysis showed a greater risk for MS with older age (OR=1.09; p=0.003) and Turkish ethnicity (OR=1.62; p=0.02).

CONCLUSION

Nearly all patients had symptoms of MS, and 40% had MS showing that this highly health-threatening condition is quite common. Therefore, effective therapy and prevention efforts must be developed for this high risk group. More migration-specific research regarding insulin resistance, MS and Type 2 DM is needed.

Preliminary data on the association between waist circumference and insulin resistance in children without a previous diagnosis

The aim of the present work was to study the association between different anthropometric parameters and insulin resistance (IR) in Spanish schoolchildren without a previous diagnosis. A total of 443 Spanish schoolchildren (9-11 years of age) were studied in this cross-sectional study. The anthropometric measurements collected were weight, height, body circumferences and skinfolds. Body mass index (BMI), waist/hip ratio, percentage body fat and fat-free body mass were determined. Overnight-fasted blood lipids, insulin and glucose levels were analysed, and estimation of IR, taking into account the homeostasis model assessment (HOMA), was calculated. The children with IR had higher serum triglycerides and insulin levels, were heavier and taller, and had a higher BMI, a larger waist circumference, a larger hip circumference, a larger waist/hip ratio and thicker bicipital and tricipital skinfolds than those who did not have IR. Age, sex, BMI and waist circumference explained 32.0% of the variance in the HOMA values; only sex, triglycerides and waist circumference independently influenced this variable. A 1-cm increase in waist circumference was associated with approximately a 3.8% increase in the mean HOMA value. The children with a waist circumference of over the p90 for their age and sex were at greater risk of showing IR as measured by the HOMA: odds ratio = 6.94 (2.01-23.91; P < 0.001). In conclusion, according to these results, waist circumference is the best anthropometric parameter associated with IR in children, and those with a waist circumference of over the p90 for their age and sex would appear to be at particular risk.

Determinants of blood glucose and insulin in healthy 9-month-old term Danish infants; the SKOT cohort

AIMS

Insulin secretion is important for early regulation of growth, but high insulin concentration is also a risk factor for insulin resistance later in life. It is therefore important to better understand how insulin and glucose are associated with early diet and growth. The aim of this study was to examine blood glucose and insulin concentration in relation to anthropometric measurements, growth, breastfeeding practice and complementary feeding in 9-month-old infants.

METHODS

This was a cross-sectional study (SKOT cohort), examining 312 healthy term infants from the age of 9 months. Of these, 265 infants had data on insulin and glucose and were included in this study. Measurements include weight, length, skinfold thickness, waist circumference, 7-day food records, 2-h fasting venous glucose and insulin analysis, and questionnaire.

RESULTS

At 9 months of age there was a strong negative association between number of breastfeedings per day and insulin concentration (P=0.0015). Insulin concentration was positively associated to waist circumference (P=0.042) and change in Z-score for weight-for-age between 5 and 9 months (P=0.004). Glucose concentration was positively associated to subscapular skinfold (P=0.002) and sum of skinfolds thicknesses (P=0.006).

CONCLUSION

At 9 months, breastfeeding still had a strong negative effect on insulin concentrations, which were positively associated with weight gain and current waist circumference, while glucose concentrations were associated with subcutaneous fat. These results are of interest in disentangling the association between early growth and later risk of disease.

Metformin and placebo therapy both improve weight management and fasting insulin in obese insulin-resistant adolescents: a prospective, placebo-controlled, randomized study

OBJECTIVE

To study whether metformin reduces obesity, homeostasis model assessment for insulin resistance index (HOMA-IR), and the metabolic syndrome (MtS) in obese European adolescents in addition to previous unsuccessful lifestyle intervention.

DESIGN AND METHODS

After 6 months of multiprofessional lifestyle intervention, 70 out of 86 adolescents without improvement in body mass index (BMI) and HOMA-IR were randomized into either the placebo (n=34) or the metformin group (2×500 mg/day, n=36) in addition to ongoing lifestyle intervention for another 6 months.

RESULTS

Age was 13.8 years, BMI was 33.1 kg/m(2), 65% were female, and 89% were Caucasians. During lifestyle intervention alone, BMI and HOMA-IR deteriorated significantly. In the subsequent medication period, HOMA-IR and fasting insulin improved similarly in the placebo and metformin groups (HOMA-IR decreased 73 vs 54% respectively in metformin versus placebo; P=0.048), but BMI remained unchanged. The insulin sensitivity index, however, only improved in the metformin group. High fasting insulin is correlated with a subsequent BMI increase irrespective of the medication. MtS remained unchanged.

CONCLUSIONS

Obese European adolescents' insulin sensitivity improved without weight change during placebo or metformin intervention in addition to lifestyle intervention. Most differences did not reach statistical significance, probably due to improved compliance with lifestyle intervention as a placebo effect. In addition, the metformin dose may be too low.

Associations between insulin and glucose concentrations and anthropometric measures of fat mass in Australian adolescents

BACKGROUND

One of the most serious, yet common co-morbidities of obesity is insulin resistance, which if untreated may progress to type 2 diabetes. This paper describes the insulin and glucose concentration distributions, the prevalence of elevated insulin, the associations between insulin and body mass index (BMI), waist circumference, waist-to-height ratio (WHtR) and fat mass index in a representative sample of Australian adolescents.

METHODS

Cross-sectional population-based study of adolescent boys and girls (N = 496, mean age 15.3 years) attending schools in metropolitan Sydney, Australia. Fasting venous blood collected and analysed for insulin and glucose concentrations. Height, weight, waist circumference measured, BMI and waist-to-height ratio calculated. Pubertal status self-reported.

RESULTS

Glucose concentrations were normally distributed and were not associated with adiposity. Insulin concentrations were distributed logarithmically, were higher among girls than boys overall and within the same ranges of BMI and waist circumference, but were lower among girls than boys within the same ranges of fat mass adjusted for height. The prevalence of elevated insulin concentration (defined as > 100 pmol/L) was 15.9% and 17.1% among boys and girls, respectively. Correlations between insulin concentration and BMI, waist circumference, WHtR and fat mass adjusted for height were 0.53, 0.49, 0.51 and 0.55, among boys, respectively, and 0.35, 0.40, 0.42 and 0.34, among girls, respectively.

CONCLUSIONS

Elevated insulin is highly correlated with adiposity in adolescents. BMI and WHtR are simple measures that can be used to identify young people who should be screened for insulin resistance and other co-morbidities.

Plasma free fatty acid reference interval in South African neonates in the first week of life

Background

Non-esterified fatty acid (NEFA) levels are an important diagnostic tool in the investigation of neonatal hypoglycaemia. NEFA reference intervals have not been reported for neonates previously.

Methods

The objective of this study was to determine an NEFA reference interval for neonates.

Results

Heparinized plasma obtained from 106 healthy neonates in the first week of life was analysed using the Roche “Free fatty acid, Half-micro test” kit. Results were then analysed statistically for normality (Shapiro–Wilk test) and reference interval determined non-parametrically (bootstrap method).

Conclusions

NEFA levels displayed a non-Gaussian distribution and the reference interval (2.5th and 97.5th percentiles) was 0.2–1.5 mmol/L (90% confidence intervals 0.1–0.3 and 1.4–2.0 mmol/L, respectively). The NEFA reference interval in South African neonates less than a week old is similar to that described in infants (1–12 months), indicating that this reference range can be used over the entire neonatal period.

Vitamin D status is modestly associated with glycemia and indicators of lipid metabolism in French-Canadian children and adolescents

In addition to its recognized role in bone health, recent studies point to vitamin D functions in other tissues, including the pancreas. We tested the association between the vitamin D status and glucose and lipid homeostasis in a school-based, cross-sectional survey of a representative sample of youth. We measured fasting plasma insulin, glucose, total cholesterol (TC), triglycerides (TG), HDL cholesterol (HDL-C) apolipoproteins (apo) A1 and B, and 25-hydroxyvitamin D [25(OH)D] concentrations in 878 boys and 867 girls. The 25(OH)D concentrations (mean +/- SD) were 45.9 +/- 12.2 nmol/L in boys and 45.9 +/- 13.0 nmol/L in girls. More than 93% of youth had suboptimal (<75 nmol/L) vitamin D concentrations. There was a slightly lower glycemia, -0.5% (P = 0.015) and -0.4% (P = 0.025), and homeostasis model assessment of insulin resistance, -2.8% (P = 0.043) and -2.3% (P = 0.050), for each 10-nmol/L increase in plasma 25(OH)D in boys and girls, respectively. In contrast, in girls only there were modest increases in plasma TC (1.1%; P = 0.017), TG (2.9%; P = 0.004), apoA1 (1.2%; P < 0.001), and apoB (1.5%; P = 0.023). We observed no association between the presence of at least 2 cardiometabolic risk factors (borderline/unfavorable fasting concentrations of apoB, HDL-C, TG, insulin, and glucose) and 25(OH)D concentrations in either boys or girls. Although the observed associations between 25(OH)D concentrations and fasting glucose, and variables of lipid metabolism are modest, they may have a potential long-term impact on cardiovascular risk.

Metformin in combination with structured lifestyle intervention improved body mass index in obese adolescents, but did not improve insulin resistance

This study assessed the efficacy of adding metformin to a structured lifestyle intervention in reducing BMI in obese adolescents with insulin resistance. Obese adolescents (25) aged 10-16 years with a body mass index (BMI) > 95th percentile and insulin resistance (Homeostasis Model Assessment-HOMA) > 3.0 were assessed in a community clinic. A structured lifestyle intervention comprising nutritional and exercise education and motivational support in both individual and group sessions was delivered over 6 months. Subjects were randomized to lifestyle intervention alone or with metformin (1500 g daily). The primary outcome measures were a change in BMI and modification of metabolic risk factors, including insulin resistance, plasma lipids and adipocytokines. Eleven adolescents receiving lifestyle and metformin intervention and 14 receiving lifestyle alone completed the study. BMI decreased by 1.8 kg/m(2) with lifestyle and metformin but did not change with lifestyle alone. HOMA was significantly decreased in the lifestyle intervention group, but not following metformin, while the adiponectin/leptin ratio improved significantly in both groups. Dyslipidemic profiles improved most significantly with metformin. We conclude that metformin in combination with a 6-month structured lifestyle intervention is effective in reducing BMI in obese adolescents but did not improve insulin resistance. Lifestyle intervention, with or without metformin, improved metabolic risk factors such as plasma lipids and adipocytokines.

Insulin sensitivity in prepubertal Caucasian normal weight children

BACKGROUND

Determining whether or not a child is insulin resistant is becoming a matter of fundamental interest even in childhood, as the incidence of metabolic complications of insulin resistance is rising. Thus reference values are needed.

AIM

To set percentiles for HOMA-IR and WBISI in Caucasian normal weight prepubertal children.

POPULATION

238 normal weight prepubertal Caucasian children (126 males/112 females).

METHODS

After physical examination including anthropometric measurements all children underwent an oral glucose tolerance test from which HOMA-IR and WBISI were calculated.

RESULTS

HOMA-IR values above the 95th percentile (2.03) and WBISI values below the 5th percentile (5.67) represent the cut-off values for the determination of insulin resistance.

CONCLUSION

These reference values are useful to easily detect insulin resistance within the prepubertal Caucasian population representing a helpful tool for clinicians to target such children in order to improve insulin sensitivity.

Association between insulin, leptin, adiponectin and blood pressure in youth

OBJECTIVE

To examine whether insulin, leptin and adiponectin are independent correlates of blood pressure (BP) in a large population-based sample of children and adolescents.

METHODS

We studied 655 boys and 667 girls aged 9, 13 and 16 years who participated in the Quebec Child and Adolescent Health and Social Survey, a province-wide school-based survey conducted in 1999.

RESULTS

Strong, positive univariate associations between BMI, insulin and leptin Z-scores, and both systolic and diastolic BP were found in both sexes. Adiponectin Z-scores were negatively associated with systolic BP in girls only. In multivariate analyses only BMI and insulin Z-scores were significantly associated with systolic BP. In boys, each 1 SD increase in BMI was associated with a 4 mmHg increase in mean systolic BP; each 1 SD increase in insulin was associated with a 1 mmHg increase in mean systolic BP. Only insulin Z-scores were independently associated with diastolic BP in both sexes. For each 1 SD increase in insulin, there was a 1 mmHg increase in mean diastolic BP in boys. Similar to systolic BP, the magnitude of the effect of insulin Z-scores on diastolic BP increased as a function of BMI Z-scores in girls.

CONCLUSION

Independently of BMI, insulin is a strong correlate of systolic and diastolic BP in youth. Although animal studies support a role for leptin and adiponectin in controlling BP, they are not independently associated with BP in youth.

Plasma PCSK9 is associated with age, sex, and multiple metabolic markers in a population-based sample of children and adolescents

BACKGROUND

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a protein convertase that posttranslationally promotes the degradation of the low-density lipoprotein receptor (LDLR) in hepatocytes and increases plasma LDL cholesterol (LDL-C). Heterozygote gain-of-function mutations of PCSK9 are associated with the familial hypercholesterolemia phenotype, whereas loss-of-function variants are associated with reduced LDL-C concentrations and lower coronary risk. Plasma PCSK9 correlates with body mass index, triglyceridemia, total cholesterol, and LDL-C in adults, but no data are available in youth.

METHODS

We studied 1739 French Canadian youth ages 9, 13, and 16 years who participated in the Quebec Child and Adolescent Health and Social Survey, a province-wide school-based survey conducted in 1999. An ELISA assay was used to measure plasma PSCK9.

RESULTS

The mean (SD) plasma PCSK9 concentration was 84.7 (24.7) microg/L in the sample. In boys, plasma PCSK9 decreased with age, whereas the inverse was true for girls. There were statistically significant positive associations between PCSK9 and fasting glucose, insulin, and HOMA-IR (homeostasis model assessment of insulin resistance). In multivariable analysis, a 10% higher fasting insulin was associated with a 1%-2% higher PCSK9 in both sexes. There were also positive associations between PCSK9 and total cholesterol, LDL-C, and triglycerides, as well as with HDL-C and apolipoproteins A1 and B.

CONCLUSIONS

PCSK9 is associated with age, sex, and multiple metabolic markers in youth. A novel finding is that PCSK9 is associated with fasting insulinemia, which suggests that PCSK9 could play a role in the development of dyslipidemia associated with the metabolic syndrome. .