Insulin sensitivity in African-American children with and without family history of type 2 diabetes

Molecular effects of Vitamin-D and PUFAs metabolism in skeletal muscle combating Type-II diabetes mellitus

Multiple post-receptor intracellular alterations such as impaired glucose transfer, glucose phosphorylation, decreased glucose oxidation, and glycogen production contribute to insulin resistance (IR) in skeletal muscle, manifested by diminished insulin-stimulated glucose uptake. Type-2 diabetes mellites (T2DM) has caused by IR, which is also seen in obese patients and those with metabolic syndrome. The Vitamin-D receptor (VDR) and poly unsaturated fatty acids (PUFAs) roles in skeletal muscle growth, shapes, and function for combating type-2 diabetes have been clarified throughout this research. VDR and PUFAs appears to show a variety of effects on skeletal muscle, in addition it shows a promising role on bone and mineral homeostasis. Individuals having T2DM are reported to suffer from severe muscular weakness and alterations in shape of the muscle. Several studies have investigated the effect on VDR on muscular strength and mass, which leads to Vitamin-D deficiency (VDD) in individuals, in which most commonly seen in elderly. VDR has been shown to affect skeletal cellular proliferation, intracellular calcium handling, as well as genomic activity in a variety of different ways such as muscle metabolism, insulin sensitivity, which is the major characteristic pathogenesis for IR in combating T2DM. The identified VDR gene polymorphisms are ApaI, TaqI, FokI, and BsmI that are associated with T2DM. This review collates informations on the mechanisms by which VDR activation takes place in skeletal muscles. Despite the significant breakthroughs made in recent decades, various studies show that IR affects VDR and PUFAs metabolism in skeletal muscle. Therefore, this review collates the data to show the role of VDR and PUFAs in the skeletal muscles to combat T2DM.

Investigating family history of diabetes as a predictor of fasting insulin and fasting glucose activity in a sample of healthy weight adults

AIMS

Type 2 diabetes is a major public health problem for the global community. Having a family history of diabetes significantly increases risk for diabetes development and understanding how family history contributes to diabetes risk could lead to more effective prevention efforts for at-risk individuals. In a previous study, we showed family history of diabetes is a significant predictor of fasting insulin in healthy weight children. The present study aimed to use the National Health and Nutrition Examination Survey (NHANES 2017) to apply similar multiple regression models to a population of healthy weight adults to determine if family history is a significant predictor of fasting glucose and fasting insulin.

METHODS

Fasting glucose (mg/dL) and fasting insulin (pmol/L) were used as dependent variables in each model, respectively, with family history of diabetes as the independent variable. Covariates for each model included age, gender, race/ethnicity, waist circumference, and macronutrient intake.

RESULTS

The model significantly predicted the variance of fasting glucose [(F(11,364) = 34.80, p < 0.001, R² = 0.2342] and fasting insulin [F(11,343) = 17.58, p < 0.001, R² = 0.1162]. After adjusting for covariates, family history was a significant predicator of fasting glucose (p = 0.0193) as well as age, gender, non-Hispanic black ethnicity, waist circumference, and fat intake. Significant predictors of fasting insulin included gender and waist circumference, but not family history (p = 0.8264). In addition, fasting glucose was higher in individuals with a family history of diabetes (p = 0.033).

CONCLUSIONS

These results add to the understanding of how family history influences the biomarkers that contribute to diabetes development. Knowledge of how family history of diabetes relates to fasting insulin and fasting glucose activity in healthy weight individuals can be used to design personalized screening and early prevention strategies.

Single Point Insulin Sensitivity Estimator for predicting type 2 diabetes mellitus in obese adolescents

PURPOSE

The prevalence of adolescents with type 2 diabetes mellitus (T2DM) has rapidly increased in Korea over the past few decades with the increase in the number of obese adolescents. The single point insulin sensitivity estimator (SPISE) was recently introduced as a surrogate marker for insulin sensitivity to predict T2DM in adults. We aimed to determine risk factors for T2DM in obese adolescents, including SPISE.

METHODS

This retrospective study included 104 adolescents diagnosed with T2DM at Korea University Hospital between January 2010 and December 2020. We compared clinical and biochemical parameters and the SPISE of normoglycemic overweight and obese individuals with those of prediabetic and diabetic adolescents to determine risk factors for T2DM. Receiver operating characteristic analysis was performed with the Youden index to determine the cutoff point of SPISE.

RESULTS

Frequency of fatty liver and family history of T2DM were significantly higher and SPISE level was significantly lower in patients with T2DM than in normoglycemic overweight/obese and prediabetic adolescents (p<0.01). A family history of T2DM, fatty liver, and SPISE value below the cutoff point (4.49) were identified as significant risk factors for T2DM in multiple logistic regression analysis after controlling for age, sex, and body mass index standard deviation score (p<0.01).

CONCLUSION

Family history of T2DM, fatty liver, and low SPISE (<4.49) are risk factors that can independently affect the occurrence of T2DM in obese adolescents. Among these risk factors, SPISE is a promising marker for predicting adolescent T2DM; careful monitoring of these individuals is needed to prevent progression to T2DM.

Youth prediabetes and type 2 diabetes: Risk factors and prevalence of dysglycaemia

BACKGROUND

The American Diabetes Association recommends risk-based screening for dysglycaemia (prediabetes and type 2 diabetes) in youth with overweight/obesity plus ≥1 risk factor. However, evidence for these recommendations is lacking.

OBJECTIVES

Examine the association between the number of risk factors and the prevalence of dysglycaemia in youth with overweight/obesity at initial presentation.

METHODS

In a paediatric obesity registry, youth (>10 and <20 years old, body mass index ≥85th percentile) were categorized into four groups according to number of risk factors (1, 2, 3 and ≥4). Based on oral glucose tolerance test, participants were classified into normal glucose tolerance or dysglycaemia.

RESULTS

Of 635 youth, 31.5% had prediabetes and 6.1% had type 2 diabetes. The prevalence of dysglycaemia was 23.1% with 1 risk factor and increased to 44.9% with ≥4 risk factors (p = 0.025). Dyslipidaemia, family history of type 2 diabetes and maternal history of gestational diabetes were significantly associated with dysglycaemia. Fasting and 2-h insulin, 2-h glucose increased (all p < 0.0001) and ALT increased (p = 0.001) with increasing risk factors. Insulin sensitivity and β-cell function deteriorated significantly with increasing risk factors.

CONCLUSION

Screening for dysglycaemia in youth with obesity and any additional risk factor is warranted to target early management.

Adiposity and family history of type 2 diabetes in an admixed population of adolescents: Associations with insulin sensitivity, beta-cell function, and hepatic insulin extraction in BRAMS study

AIMS

Insulin resistance and beta-cell dysfunction manifest differently across racial/ethnic groups, and there is a lack of knowledge regarding the pathophysiology of type 2 diabetes mellitus (T2DM) for ethnically admixed adolescents. This study aimed to investigate the influence of adiposity and family history (FH) of T2DM on aspects of insulin sensitivity, beta-cell function, and hepatic insulin extraction in Brazilian adolescents.

METHODS

A total of 82 normoglycemic adolescents were assessed. The positive FH of T2DM was defined as the presence of at least one known family member with T2DM. The hyperglycemic clamp test consisted of a 120-min protocol. Insulin secretion and beta-cell function were obtained from C-peptide deconvolution. Analysis of covariance considered pubertal stage as a covariate.

RESULTS

Both lean and overweight/obese adolescents had similar glycemic profiles and disposition indexes. Overweight/obese adolescents had about 1/3 the insulin sensitivity of lean adolescents (1.1 ± 0.2 vs. 3.4 ± 0.3 mg·kg·min·pmol ∗ 1000), which was compensated by an increase around 2.5 times in basal (130 ± 7 vs. 52 ± 10 pmol·l·min) and total insulin secretion (130,091 ± 12,230 vs. 59,010 ± 17,522 pmol·l·min), and in the first and second phases of insulin secretion; respectively (p < 0.001). This increase was accompanied by a mean reduction in hepatic insulin extraction of 35%, and a 2.7-time increase in beta-cell glucose sensitivity (p < 0.05). The positive FH of T2DM was not associated with derangements in insulin sensitivity, beta-cell function, and hepatic insulin extraction.

CONCLUSIONS

In an admixed sample of adolescents, the hyperglycemic clamp test demonstrated that adiposity had a strong influence, and FH of T2DM had no direct influence, in different aspects of glucose metabolism.

Maternal and paternal family history of diabetes in second-degree relatives and metabolic outcomes at age 5-6 years: The ABCD Study

AIM

To investigate whether children with a family history of diabetes (FHD) in second-degree relatives (grandparents, aunts/uncles) are at increased risk of developing obesity and diabetes, and whether the risk differs between maternal or paternal transmission.

METHODS

In the multiethnic population-based cohort Amsterdam-Born Children and Their Development (ABCD) Study, body mass index (BMI), waist-to-height ratio (WHR), fat percentage (fat%), fasting glucose and C-peptide in 5- or 6-year-old children with no second-degree FHD (n=2226) were compared with children with maternal-only (n=353), paternal-only (n=281) or both maternal and paternal (n=164) second-degree FHD. Children of diabetic mothers or fathers were excluded.

RESULTS

None of the children in any of our FHD categories differed in body composition after adjusting for maternal, paternal and childhood lifestyle covariates. However, children with both maternal and paternal second-degree FHD had increased C-peptide levels (0.03nmol, 95% CI: 0.01-0.05) compared with those in the other three study groups. Results were similar when analyses were restricted to only the Dutch children.

CONCLUSION

Children with FHD in second-degree relatives on both maternal and paternal sides already have higher C-peptide levels at an early age. This might be the result of a double burden of a shared obesogenic lifestyle, or of more diverse diabetogenic genes compared to children without FHD or with only FHD in one side of the family. In any case, second-degree FHD could be used as a public-health screening tool to identify children at risk of adverse metabolic outcomes and of possible future disease.

The treatment of type 2 diabetes mellitus in youth : which therapies?

Type 2 diabetes mellitus in children and adolescents is becoming an increasingly important public health concern throughout the world. This epidemic is closely associated with the increased prevalence of obesity among youth of all ethnic backgrounds, as increased visceral adipose tissue produces adipokines that increase insulin resistance. Type 2 diabetes represents one arm of the metabolic syndrome, which includes abdominal obesity, disturbed glucose regulation and insulin resistance, dyslipidemia, and hypertension. The treatment of type 2 diabetes and the metabolic syndrome poses a challenge for pediatric endocrinologists. This review provides information regarding diagnosis of type 2 diabetes in children, as well as prevention strategies, such as lifestyle modification and pharmacologic options for weight loss, including metformin, orlistat, and sibutramine. Pharmacologic treatment options, their modes of action, and clinical indications for use are also reviewed. Treatment regimens for youth-onset type 2 diabetes that are discussed include metformin, sulfonylureas, glucosidase inhibitors, thiazolidinediones, glucagon-like peptide-1, and insulin.

Mitochondrial DNA content and function, childhood obesity, and insulin resistance

OBJECTIVES

The objectives of our study were to compare the mitochondrial enzyme activity between obese and non-obese children and to assess the association between mitochondrial DNA content and function and markers of metabolic syndrome.

METHODS

Clinical and anthropometric data of obese and normal-weight children ages 2-18 years were collected. We collected buccal swabs for mitochondrial respiratory enzymes (complex I, IV, and Citrate Synthase). In obese children only, serum levels of metabolic parameters and mitochondrial DNA from mononuclear cells were quantitated.

RESULTS

We recruited 75 obese and 65 normal-weight children. There was no difference in respiratory complex enzyme activity levels between obese and normal-weight subjects. In obese subjects, mitochondrial to nuclear DNA (mt/nDNA) ratio was significantly correlated with BMI Z-score and BMI percentile (p < 0.05, and p < 0.01, respectively), and the strength of this correlation was proportionate to the degree of obesity. We did not find any association between mt/nDNA ratio and metabolic parameters. We observed a significant positive association between complex IV activity and fasting insulin level (p < 0.05). Finally, fasting insulin explained 45% of the variation in the complex IV activity level (p < 0.05).

CONCLUSION

Our findings indicate that mitochondrial DNA content is directly related to obesity, but not to the markers of metabolic syndrome/insulin resistance in children. Longitudinal studies involving larger samples are needed to confirm our findings and help elucidate the relationship between mitochondrial function, adiposity, and insulin resistance.

Pre-diabetes in overweight youth and early atherogenic risk

PURPOSE

To compare atherogenic lipoprotein particles and vascular smooth muscle biomarkers in overweight youth with pre-diabetes (PD) vs. normal glucose tolerance (NGT).

METHODS

144 adolescents (60 black, 84 white; 102 female; PD=45, NGT=99) aged 10-19 years underwent a fasting blood draw and 2-h OGTT. Lipoprotein particle size and subclass concentration and vascular smooth muscle biomarkers (ICAM-1, VCAM-1 and E-selectin) were compared between youth with PD and NGT.

RESULTS

Compared with NGT, PD adolescents had smaller LDL (mean±SE: 20.5±0.1 vs. 21.0±0.1 nm; P=0.002) and HDL (8.62±0.05 vs. 8.85±0.04 nm; P=0.013) size and elevated medium small (159.2±10.3 vs. 123.8±6.4 nmol/L; P=0.037) and very small (626.3±45.4 vs. 458.5±26.4 nmol/L; P=0.032) LDL particle concentrations, after adjustment for race and BMI. Further adjusting for fasting insulin or visceral adiposity obviated these differences between the groups except for LDL size. ICAM-1 and E-selectin did not differ in youth with PD but correlated with LDL and HDL size, and small LDL particle concentrations.

CONCLUSIONS

Overweight adolescents with PD have an atherogenic lipoprotein profile of small LDL and HDL size and increased concentrations of small LDL, moderated by insulin resistance and visceral adiposity, but independently driven by dysglycemia for LDL size. Associations between smooth muscle biomarkers and lipoproteins could be an early signal heralding the atherogenic process. It remains to be determined if correction of dysglycemia and associated lipoprotein abnormalities in obese youth could prove effective in halting this process.

A cross-sectional study to determine the prevalence of obesity and other risk factors for type 2 diabetes among school children in Trinidad, West Indies

BACKGROUND

Our previous work has shown that type 2 diabetes mellitus is a problem in the school-aged population of Trinidad, West Indies. The current study evaluated the prevalence in this population of selected risk factors for diabetes, viz: obesity, family history of diabetes and acanthosis nigricans.

OBJECTIVE

To assess the prevalence of the following risk factors for type 2 diabetes (T2DM) in school children in Trinidad: obesity, family history of diabetes in first- or second-degree relatives and the presence of acanthosis nigricans (AN).

METHODS

A cross-sectional survey was performed among school children aged 7-18 years from September 2009 to June 2010. A convenience sample was selected from a random sample of 32 schools drawn from all educational districts. A self-administered questionnaire was employed to record family history, gender and ethnicity. AN was assessed and scored clinically at the neck and obesity was measured by anthropometry and bio-impedance.

RESULTS

There were 2130 participants in the study. Fifteen per cent were obese and 17% were overweight. Primary school children had a higher prevalence of obesity (22·9% vs 11·0%) and overweight (20·0% vs 15·6%) than secondary school children (P<0·05). A greater proportion of males than females had combined overweight/obesity as measured by BMI for age (35·8 vs 29·4%, P<0·05). The overall prevalence of AN was 43·4%. However, just over 18% of all school children have a degree of AN greater than grade 2, which clinically is readily recognisable. Females displayed this physical sign more commonly than males (P<0·05). The prevalences of a family history of diabetes in first- and second-degrees relatives were 11·0% and 1·1%, respectively. Forty-three per cent had one risk factor for diabetes, 23·1% had two and 2·9% had three.

CONCLUSION

Risk factors for T2DM are very common among school children in Trinidad. More than 40% had at least one risk factor. Strategies aimed at reducing risk factors for T2DM, especially obesity, among Trinidadian school children are urgently warranted.

Cardiovascular risk in children and adolescents with type 2 diabetes mellitus

The epidemic of childhood obesity worldwide has led to increased incidence of the metabolic syndrome and type 2 diabetes in the pediatric and adolescent population. As such, there is increasing concern that this large population of children is at risk for the long-term complications of diabetes, specifically cardiovascular disease. With cardiovascular disease remaining the leading cause of death in adults, this presents a significant public health concern as these children age. In this article, we discuss cardiovascular disease and risk in children and adolescents with type 2 diabetes, including the epidemiology of type 2 diabetes, atherosclerotic cardiovascular disease, obesity, hypertension, and left ventricular function.

Estimation of the disposition index based on components of metabolic syndrome

Decreased insulin sensitivity (IS) and impaired insulin secretion are major pathological features of type 2 diabetes (T2DM). The product of these factors is the disposition index (DI). We aimed to develop an equation for predicting DI. We enrolled 167 participants in our study. We randomly assigned 126 (75%) of the participants to the study group, whose data would be used to build the equation for estimating the DI. The remaining 41 participants comprised the external validation group. A frequently sampled intravenous glucose-tolerance test was performed for all participants, and the IS, the glucose sensitivity, the acute insulin response to the glucose load, and the DI were determined. Three factors were selected from multiple linear regression analysis, and we constructed the equation log (DI) = 2.449 - 0.113 × fasting plasma glucose + 0.046 × body mass index - 0.612 × high-density lipoprotein cholesterol. Using this equation, the calculated log (DI) significantly correlated with the measured log (DI) in the external validation group (r = 0.428, p = 0.007). By using the equation based on the demographic data and measurements of metabolic syndrome components, the DI could be predicted with acceptable accuracy (r = 0.428). Because of the relationships between the MetS and demographic parameters, this method of predicting DI may help further clinicians' understanding of the underlying pathological mechanisms in T2DM.

25-Hydroxyvitamin D in obese youth across the spectrum of glucose tolerance from normal to prediabetes to type 2 diabetes

OBJECTIVE

To 1) determine if plasma 25-hydroxyvitamin D (25[OH]D) concentrations differ among obese youth with normal glucose tolerance (NGT) versus prediabetes versus type 2 diabetes and 2) assess the relationships between 25(OH)D and in vivo insulin sensitivity and β-cell function in this cohort.

RESEARCH DESIGN AND METHODS

Plasma 25(OH)D concentrations were examined in banked specimens in 9- to 20-year-old obese youth (n = 175; male 42.3%, black 46.3%) (NGT, n = 105; impaired glucose tolerance [IGT], n = 43; type 2 diabetes, n = 27) who had in vivo insulin sensitivity and secretion measured by hyperinsulinemic-euglycemic and hyperglycemic clamp techniques and had an assessment of total body composition and abdominal adiposity.

RESULTS

The mean age and BMI of the subjects were 14.3 ± 2.1 years and 35.7 ± 5.6 kg/m(2), respectively. BMI, plasma 25(OH)D, and the proportion of vitamin D-deficient and -insufficient children did not differ across the three groups. Furthermore, there was no association between 25(OH)D and in vivo insulin sensitivity or β-cell function relative to insulin sensitivity (disposition index) in all groups combined or in each group separately.

CONCLUSIONS

Our data in obese youth show 1) no differences in plasma 25(OH)D concentrations across the glucose tolerance groups and 2) no relationship between 25(OH)D and in vivo insulin sensitivity and β-cell function relative to insulin sensitivity in any of the groups. It remains uncertain if enhancement of the vitamin D status could improve pathophysiological mechanisms of prediabetes and type 2 diabetes in obese youth.

The Frequency of Type 2 Diabetes Mellitus among Diabetic Children in El Minia Governorate, Egypt

OBJECTIVES

Type 2 diabetes mellitus (T2DM) in children and adolescents is becoming an increasingly important public health concern throughout the world. This study aimed to estimate the frequency of T2DM among diabetic young people in El-Minia Governorate, Egypt, and to detect its risk factors.

METHODS

A total of 210 diabetic patients under 18 years old in Minia Governorate were included in the study and underwent a thorough history-taking, a physical examination and laboratory investigations.

RESULTS

T2DM was present in 28 patients (13.3%); it was significantly present in 18 females (64.3%) and 20 (71.4%) of them had a positive family history of DM. T2DM patients had significantly higher BMI and waist circumference centiles for age and sex than those with T1DM. Also, haemoglobin A1c %, serum C-peptide and cholesterol levels were significantly higher in T2DM than T1DM patients. Finally, there were weak significant positive correlations between C-peptide level and both BMI and waist circumference.

CONCLUSION

T2DM is no longer a disease of adults but can also occur in children and adolescents. The results suggested that obesity, female gender and a positive family history of DM are risk factors for T2DM. Also, patients with T2DM had poorer glycaemic control and hypercholesterolemia than those with other types of diabetes.

Metabolomic profiling of fatty acid and amino acid metabolism in youth with obesity and type 2 diabetes: evidence for enhanced mitochondrial oxidation

OBJECTIVE

We compared acylcarnitine (AcylCN) species, common amino acid and fat oxidation (FOX) byproducts, and plasma amino acids in normal weight (NW; n = 39), obese (OB; n = 64), and type 2 diabetic (n = 17) adolescents.

RESEARCH DESIGN AND METHODS

Fasting plasma was analyzed by tandem mass spectrometry, body composition by dual energy X-ray absorptiometry and computed tomography, and total-body lipolysis and substrate oxidation by [(2)H(5)]glycerol and indirect calorimetry, respectively. In vivo insulin sensitivity (IS) was assessed with a 3-h hyperinsulinemic-euglycemic clamp.

RESULTS

Long-chain AcylCNs (C18:2-CN to C14:0-CN) were similar among the three groups. Medium- to short-chain AcylCNs (except C8 and C10) were significantly lower in type 2 diabetes compared with NW, and when compared with OB, C2-, C6-, and C10-CN were lower. Amino acid concentrations were lower in type 2 diabetes compared with NW. Fasting lipolysis and FOX were higher in OB and type 2 diabetes compared with NW, and the negative association of FOX to C10:1 disappeared after controlling for adiposity, Tanner stage, and sex. IS was lower in OB and type 2 diabetes with positive associations between IS and arginine, histidine, and serine after adjusting for adiposity, Tanner stage, and sex.

CONCLUSIONS

These metabolomics results, together with the increased rates of in vivo FOX, are not supportive of defective fatty acid or amino acid metabolism in obesity and type 2 diabetes in youth. Such observations are consistent with early adaptive metabolic plasticity in youth, which over time-with continued obesity and aging-may become dysfunctional, as observed in adults.

Insulin sensitivity and β-cell function in normoglycemic offspring of individuals with type 2 diabetes mellitus: Impact of line of inheritance

AIMS

The aim was to study the effect of family history of type 2 diabetes mellitus (T2DM) on insulin sensitivity and β-cell function in normoglycemic offspring.

MATERIAL AND METHODS

Offspring of T2DM patients (cases) and individuals without family history of T2DM (controls) were the subjects for this cross-sectional study. All participants underwent 75 g OGTT and samples were collected for plasma insulin, C-peptide, and proinsulin at 0, 30, 60, and 120 minutes.

RESULTS

A total of 271 cases (age 22 ± 10 years; 53% males) and 259 controls (28 ± 10 years, 66% males) were enrolled for the study. BMI, plasma insulin, C-peptide, proinsulin, HOMA-IR, and insulinogenic index (0-120) were significantly higher and whole-body insulin sensitivity (WBISI) and disposition index (0-120) [DI 120] were lower in cases compared to controls. After adjusting for BMI, proinsulin at 120 minutes, area under the curve (AUC) of proinsulin (during OGTT) and AUC proinsulin/AUC C-peptide were significantly higher in cases. Cases were subdivided into four groups according to inheritance pattern; paternal DM (PDM), maternal DM (MDM), grandparental DM (GPDM), and both parents DM (BPDM). The magnitude of differences varied with relationship (greater when both parents and grandparents were affected). Mean HOMA-IR was higher by 127% and 50% and DI 120 was lower by 33% and 18% (adjusted for age and gender) in the BPDM and GPDM groups respectively compared to controls.

CONCLUSIONS

We observed higher BMI, plasma insulin, C-peptide, and proinsulin and lower insulin sensitivity and β-cell compensation in normoglycemic offspring of T2DM subjects compared to controls. Differences were greater when both parents and grandparents had T2DM.

Efficacy and safety of a tight glucose control protocol in critically ill term neonates

BACKGROUND

A large single-center randomized trial showed that treating hyperglycemia in critically ill children improved outcome, despite an increased incidence of hypoglycemia, especially in infants.

OBJECTIVES

We evaluated the efficacy and incidence of hypoglycemia using a tight glucose protocol in critically ill term neonates.

METHODS

Term hyperglycemic (>8 mmol·l(-1); >144 mg·dl(-1)) neonates treated with a tight glucose protocol during a 3.5-year period in a tertiary pediatric intensive care unit were retrospectively analyzed.

RESULTS

Seventy-three term hyperglycemic neonates [age 0 days (0-6), weight 3.2 ± 0.8 kg, PRISM 16 (11-20)] were included for analysis. Eighteen neonates died (25%). The initial mean (range) glucose level was 11.1 mmol·l(-1) [9.6-15.2; 200 mg·dl(-1) (173-274)], and normoglycemia (<8 mmol·l(-1); <144 mg·dl(-1)) was reached within 5.3 h (1-25) with an overall treatment duration of 27 h (10-57). Seven hypoglycemic incidents (5 times ≤2.2 mmol·l(-1); 40 mg·dl(-1), and 2 times <1.7 mmol·l(-1); 31 mg·dl(-1)) occurred in 5 (6.7%) infants, without severe clinical signs. Three hypoglycemic incidents were directly explained due to a protocol violation. One hypoglycemic incident occurred with the onset of sepsis, while no apparent cause was identified for three hypoglycemic incidents.

CONCLUSIONS

Our glucose protocol was effective, but hypoglycemia occurred more frequently than in older children reported previously. Potential differences in glucose and insulin metabolism in term neonates appear to justify additional safety approaches, while awaiting further studies assessing the benefits of tight glucose protocols in this population. Meanwhile, we have decreased the initial insulin starting doses in our protocol.

Current recommended parenteral protein intakes do not support protein synthesis in critically ill septic, insulin-resistant adolescents with tight glucose control

OBJECTIVE

To investigate the effects of insulin infusion and increased parenteral amino acid intakes on whole body protein balance, glucose kinetics, and lipolysis in critically ill, insulin-resistant, septic adolescents.

DESIGN

A single-center, randomized, crossover study.

SETTING

A medicosurgical intensive care unit in a tertiary university hospital.

PATIENTS

Nine critically ill, septic adolescents (age 15.0 ± 1.2 yrs, body mass index 20 ± 4 kg m(-2)) receiving total parenteral nutrition.

INTERVENTIONS

Patients received total parenteral nutrition with standard (1.5 g · kg(-1) · day(-1)) and high (3.0 g · kg(-1) · day(-1)) amino acid intakes in a 2-day crossover setting, randomized to the order in which they received it. On both study days, we conducted a primed, constant, 7-hr stable isotope tracer infusion with [1-(13)C]leucine, [6,6-(2)H(2)]glucose, and [1,1,2,3,3-(2)H(5)]glycerol, in combination with a hyperinsulinemic euglycemic clamp during the last 3 hrs.

MEASUREMENTS AND MAIN RESULTS

Insulin decreased protein synthesis at standard amino acid and high amino acid intakes (p < .01), while protein breakdown decreased with insulin at standard amino acid intake (p < .05) but not with the high amino acid intake. High amino acid intake improved protein balance (p < .05), but insulin did not have an additive effect. There was significant insulin resistance with an M value of ~3 (mg · kg(-1) · min(-1))/(mU · mL(-1)) which was 30% of reported normal values. At high amino acid intake, endogenous glucose production was not suppressed by insulin and lipolysis rates increased.

CONCLUSION

The current recommended parenteral amino acid intakes are insufficient to maintain protein balance in insulin-resistant patients during tight glucose control. During sepsis, insulin decreases protein synthesis and breakdown, and while high amino acid intake improves protein balance, its beneficial effects may be offset by enhanced endogenous glucose production and lipolysis, raising concerns that insulin resistance may have been exacerbated and that gluconeogenesis may have been favored by high amino acid intakes. Dose-response studies on the effect of the level of amino acid intakes (protein) on energy metabolism are needed.

Vitamin D status, adiposity, and lipids in black American and Caucasian children

OBJECTIVE

The aim of the study was to examine the relationship between vitamin D status, total and abdominal adiposity, and lipids in black and white children.

METHODS

Plasma 25-hydroxyvitamin D [25(OH)D], adiposity [body mass index (BMI), percentage of total body fat, visceral adipose tissue (VAT), sc adipose tissue (SAT)], and fasting lipids were assessed in healthy obese and nonobese 8- to 18-yr-old black and white children.

RESULTS

We studied 237 children (mean ± sd age, 12.7 ± 2.2 yr; 47% black, 47% obese, and 43% male). Mean 25(OH)D concentration for the entire cohort was 19.4 ± 7.4 ng/ml. The majority of the children were vitamin D deficient [25(OH)D < 20 ng/ml; 73% blacks, 40% whites]. Plasma 25(OH)D was associated inversely with BMI, BMI percentile, percentage of total body fat, VAT, and SAT and positively with HDL cholesterol in the entire cohort. VAT was higher in vitamin D-deficient whites, and SAT was higher in vitamin D-deficient blacks compared with their respective vitamin D-nondeficient counterparts. Race, season, pubertal status, and VAT were independent significant predictors of 25(OH)D status.

CONCLUSIONS

In black and white youth examined together, lower levels of 25(OH)D are associated with higher adiposity measures and lower HDL. Furthermore, vitamin D deficiency is associated with higher VAT in whites and greater SAT in blacks. Besides therapeutic interventions to correct the high rates of vitamin D deficiency in youth, benefits of vitamin D optimization on adiposity measures and lipid profile need to be explored.

Measurement site of visceral adipose tissue and prediction of metabolic syndrome in youth

OBJECTIVE

It is unknown whether measurement site of visceral adipose tissue (VAT) influences the relationship between VAT and associated health risk in youth and if so, whether ethnic differences exist in this relationship. We examined the influence of the measurement site of VAT on the relationships between VAT and metabolic syndrome (MetS) in African-American (AA) and American-White (AW) youth.

SUBJECTS

Healthy AA (n = 54) and AW (n = 54) children and adolescents (age: 8-18 yr; BMI: 15.3-42.5 kg/m(2)).

MEASUREMENTS

VAT mass was derived using a series of five transverse images measured by magnetic resonance imaging, extending from 5 cm below to 15 cm above L4-L5. MetS was defined using a modified IDF criteria.

RESULTS

In AA, VAT measure at 5 cm above L4-L5 (R(2) = 0.93) was most strongly (p < 0.05) correlated with VAT mass and was a significantly (p < 0.05) stronger correlate as compared to L4-L5 (R(2) = 0.84). In AW, VAT measures at 5 cm (R(2) = 0.93) and 10 cm (R(2) = 0.93) above L4-L5 were most strongly (p < 0.05) correlated with VAT mass; however, these were not stronger correlates as compared to L4-L5 (R(2) = 0.91). In AW, all VAT measures were significantly (p < 0.05) associated with an increased odds ratio (OR) for prevalent MetS, wherein the VAT mass [OR = 5.32(1.9-15.0)] and VAT at L4-L5[OR = 5.99(1.9-18.4)] were most strongly associated with MetS. In contrast, only VAT at 10 cm above L4-L5 [OR = 4.39 (1.1-18.1)] was significantly (p < 0.05) associated with MetS in AA.

CONCLUSION

In AA and AW youth, the measurement site for VAT has impact on the estimation of total VAT and the magnitude of the association with obesity-related health risks.

Pathogenesis of insulin resistance in skeletal muscle

Insulin resistance in skeletal muscle is manifested by decreased insulin-stimulated glucose uptake and results from impaired insulin signaling and multiple post-receptor intracellular defects including impaired glucose transport, glucose phosphorylation, and reduced glucose oxidation and glycogen synthesis. Insulin resistance is a core defect in type 2 diabetes, it is also associated with obesity and the metabolic syndrome. Dysregulation of fatty acid metabolism plays a pivotal role in the pathogenesis of insulin resistance in skeletal muscle. Recent studies have reported a mitochondrial defect in oxidative phosphorylation in skeletal muscle in variety of insulin resistant states. In this review, we summarize the cellular and molecular defects that contribute to the development of insulin resistance in skeletal muscle.

Increased prevalence of abnormal glucose tolerance among obese siblings of children with type 2 diabetes

OBJECTIVE

To test the hypothesis that overweight siblings of children with type 2 diabetes mellitus (T2DM) have a higher prevalence of abnormal glucose tolerance (AGT) compared with other overweight children.

STUDY DESIGN

This was a cross-sectional study of overweight (body mass index [BMI] >or= 95(th) percentile) subjects, age 8 to 17 years, with at least 1 sibling age >or= 12 years. The primary outcome was AGT, as assessed by the oral glucose tolerance test (2-hour glucose >or= 140 mg/dL). The secondary outcome was insulin resistance by homeostasis model assessment (HOMA).

RESULTS

The sibling (n=20) and control (n=42) groups were similar in terms of age, sex, racial distribution (largely African American), pubertal status, and BMI. The prevalence of AGT in the sibling group was 40.0% (n=8), compared with 14.3% (n=6) in controls (P= .048, Fisher exact test; unadjusted odds ratio=4.0; 95% confidence interval=1.2 to 13.5). Univariate analysis did not identify confounders for either outcome. There were no significant differences in HOMA or hemoglobin A1c between the 2 groups.

CONCLUSIONS

Overweight siblings of children with T2DM had 4 times greater odds of having AGT compared with other overweight children. This group may represent a particularly high-risk population to target for screening and pediatric T2DM prevention.

Hyperinsulinemia in African-American adolescents compared with their American white peers despite similar insulin sensitivity: a reflection of upregulated beta-cell function?

OBJECTIVE

African-American (AA) children are hyperinsulinemic and insulin resistant compared with American white (AW) children. Previously, we demonstrated that insulin secretion relative to insulin sensitivity was approximately 75% higher in AA compared with AW children, suggesting that hyperinsulinemia in AA children is not merely a compensatory response to lower insulin sensitivity. The aim of the present investigation was to assess whether glucose-stimulated insulin response is higher in AA versus AW adolescents who have comparable in vivo insulin sensitivity.

RESEARCH DESIGN AND METHODS

The hyperinsulinemic-euglycemic and hyperglycemic clamp techniques were utilized to assess first- and second-phase insulin secretion. Insulin secretion relative to insulin sensitivity was calculated as the glucose disposition index.

RESULTS

AA adolescents compared with their AW peers with comparable insulin sensitivity and body composition had higher first-phase insulin concentrations.

CONCLUSIONS

The quantitative relationship between insulin sensitivity and first-phase insulin appears to differ among AA and AW adolescents.

Race and gender differences in the relationships between anthropometrics and abdominal fat in youth

OBJECTIVE

We examined the influence of race and gender on abdominal adipose tissue (AT) distribution for a given anthropometric measure including waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-height (W/Ht) in youth.

METHODS AND PROCEDURES

Subjects included healthy 62 black and 98 white youth. A single transverse image of the abdomen (L4-L5) was obtained using computed tomography.

RESULTS

For a given BMI, there was a significant (P<0.05) main effect of race and sex on the relationship between BMI and WC, such that boys and whites had a higher WC than girls and blacks. There was a significant (P<0.05) main effect and interaction effect of gender on the relationship between WC and visceral AT, such that boys had a higher visceral AT than girls, and the difference was magnified with increasing WC. For a given WC, black boys and girls had higher abdominal subcutaneous AT (SAT) than white peers, wherein the magnitude of the difference is increased with increasing WC. For a given W/Ht, black boys had significantly (P<0.05) lower visceral AT than white boys, but with no difference in girls. Black boys and girls had higher SAT than white peers, wherein the magnitude of the difference is increased with increasing W/Ht.

DISCUSSION

Our findings demonstrate a significant race and gender differential in the abdominal AT distribution for a given BMI, WC, WHR, and W/Ht. Future studies should take these differences into consideration when developing race- and gender-specific anthropometric cut-offs for obesity and obesity-related health risks in youth.

Insulin resistance, physical fitness, body composition and leptin concentration in 7–8 year-old children

The aim of this study was to investigate the association between insulin resistance and physical fitness, leptin concentration, body composition and family history for diabetes in non-selected young children. Physical fitness, fasting plasma glucose, insulin and leptin concentrations, anthropometric characteristics and medical history were available in two hundred and fifty-seven 7-year-old Dutch children. Correlations with the homeostasis model assessment (HOMA) index for insulin resistance were studied. A multiple regression model was calculated for HOMA. The differences between children with or without a family history for diabetes were not significant. Boys scored higher on glucose concentration and aerobic fitness and lower on sum of skin folds and leptin concentration (p<.05). After adjustment for sum of skin folds, HOMA was significantly associated with leptin in both genders (boys r=.184 p=.031; girls r=.430 p=.000). The association between physical fitness and HOMA was mediated by sum of skin folds. The associations were stronger in girls than in boys. In the regression model (R(2)=.205) the leptin concentration was the only significant predictor for HOMA. The influence of family history for diabetes on insulin resistance is shown as a trend at this age. Our findings suggest that plasma leptin concentration is independently associated with the development of insulin resistance in a non-selected prepubertal population. The association of physical fitness with insulin resistance seems to be mediated by the sum of skin folds.

Association of abdominal fat distribution and cardiometabolic risk factors among obese Korean adolescents

The association between abdominal fat distribution and cardiometabolic risk factors using direct measures of abdominal fat in adolescents has not been extensively researched. This study was designed to investigate the association between visceral and subcutaneous fat and cardiometabolic risk factors, in obese Korean adolescents. The study enrolled 175 adolescents (72 boys, 103 girls), from ages nine to 19 years, who were referred to the Obesity Clinic of Asan Medical Center. Body mass index (BMI) and waist circumference (WC) were measured for each study participant. Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) areas were calculated by computed tomography. Blood pressure, fasting plasma glucose, total cholesterol, triglycerides, HDL cholesterol, insulin and homeostasis model assessment (HOMA) score were measured. Systolic blood pressure, HDL cholesterol, fasting insulin and the HOMA score were significantly correlated with BMI, WC, VAT and SAT. In addition, VAT was significantly correlated with diastolic blood pressure and triglyceride levels. On multiple regression analysis, VAT was independently correlated with blood pressure, triglycerides, HDL cholesterol, fasting insulin and the HOMA score, while SAT was independently correlated with systolic blood pressure, fasting insulin and the HOMA score. This study determined that cardiovascular risk factors are closely associated with VAT, while insulin resistance is closely associated with both VAT and SAT among obese Korean adolescents.

Genetics and type 2 diabetes in youth

The rapid increase in the population prevalence of type 2 diabetes mellitus (T2DM) in youth can only be explained by changes in lifestyle. However, even when most members of a population have changed their lifestyle, only a minority of children develop diabetes, and genetic factors are important in determining which children are affected. Support for the role of genetic factors comes from epidemiological evidence that diabetes in youth is most common in high diabetes prevalence racial groups, in subjects with a strong family history, and in girls. Defining the genes predisposing to T2DM is extremely difficult as there are multiple genes involved each contributing only a small amount and lifestyle factors play a large role. Defining the molecular genetics of T2DM in youth is even harder because in addition to the low number of subjects, there is also the ethnic heterogeneity of the subjects and the lack of robust diagnostic criteria. Recently, there has been considerable progress in defining the predisposing genes for adults with T2DM using thousands of cases and controls and a collaborative genome-wide approach. Similar numbers will be needed to assess if the genes found in adults also predispose to T2DM of youth and this will require large multi-center studies. Progress to date in the molecular genetics of T2DM in youth is limited to one population, the Oji-Cree Native Canadians, where the private variant - G319S - a variant of HNF1A strongly predisposes to diabetes in children as well as in adults.

Targeting obesity to reduce the risk for type 2 diabetes and other co-morbidities in African American youth: a review of the literature and recommendations for prevention

Over the last decade, the prevalence of obesity has continued to rise within the adolescent population of the US. Data show that African American youth are disproportionately affected by the obesity epidemic due to their higher risk for obesity-related co-morbidities, such as type 2 diabetes. Interventions that target risk factors for obesity at the individual, family and community levels are needed in order to prevent the onset of type 2 diabetes and related complications. This article provides an overview of the prevalence of obesity and type 2 diabetes in African American youth, the pathophysiology of the disease, and the behavioural risk factors that have contributed to its high prevalence within the African American adolescent population. Successful intervention strategies that target modifiable risk factors, such as diet and physical activity, will be identified. Finally, recommendations for programmes to prevent the onset of type 2 diabetes within the African American adolescent population are presented.

Growth hormone treatment in adolescent males with idiopathic short stature: changes in body composition, protein, fat, and glucose metabolism

CONTEXT

Cross-sectional observations show an inverse relationship between pubertal increase in GH and insulin sensitivity, suggesting that pubertal insulin resistance may be mediated by GH.

OBJECTIVE

Our objective was to assess longitudinally the effects of short-term GH supplementation in adolescent males with non-GH-deficient idiopathic short stature (ISS) on body composition, substrate metabolism, and insulin sensitivity. Children with ISS were studied to simulate the pubertal increase in GH secretion.

PARTICIPANTS AND SETTING

Eight males with ISS (10.8-16.5 yr) were recruited from pediatric endocrinology clinics at an academic medical center.

STUDY DESIGN

Participants were evaluated in the General Clinical Research Center before and after 4 months of GH supplementation (0.3 mg/kg.wk). Body composition was assessed with dual-energy x-ray absorptiometry. Whole-body glucose, protein, and fat turnover were measured using stable isotopes. In vivo insulin action was assessed during a 3-h hyperinsulinemic (40 mU/m(2).min) euglycemic clamp.

RESULTS

GH supplementation led to 1) increase in hepatic glucose production and fasting insulin levels, 2) increase in lean body mass and decrease in fat mass, and 3) improvement in cardiovascular lipid risk profile. Plasma IGF-I levels correlated positively with insulin levels.

CONCLUSIONS

Four months of GH supplementation in adolescent males with ISS is associated with significant body composition changes and hepatic insulin resistance.

Insulin resistance: link to the components of the metabolic syndrome and biomarkers of endothelial dysfunction in youth

OBJECTIVE

We examined the relationship of in vivo insulin sensitivity to the components of the metabolic syndrome and biomarkers of endothelial dysfunction in youth.

RESEARCH DESIGN AND METHODS

Subjects included 216 youths (8-19 years of age) who participated in a 3-h hyperinsulinemic-euglycemic clamp.

RESULTS

Independent of race, the frequencies of central obesity, high triglycerides, low HDL, high blood pressure, impaired fasting glucose, and impaired glucose tolerance were significantly higher (P < 0.05) in the lowest versus highest quartile of insulin sensitivity. BMI, abdominal adiposity, systolic blood pressure, and triglycerides increased and adiponectin and HDL decreased significantly (P for trend for all <0.05), with decreasing insulin sensitivity in both races. After controlling for BMI, insulin resistance remained associated (P < 0.05) with visceral adipose tissue in both races (P for trend = 0.01 in blacks and 0.08 in whites). In whites but not blacks, lower insulin sensitivity was associated (P < 0.05) with higher intercellular adhesion molecule-1 (ICAM-1) and E-selectin levels; however, these relationships did not remain significant (P > 0.05) once visceral adipose tissue was controlled for.

CONCLUSIONS

The prevalence of the individual components of metabolic syndrome increases with decreasing insulin sensitivity in black and white youth. In whites but not blacks, insulin resistance is associated with increased circulating endothelial biomarkers. It remains to be determined if lower abdominal adiposity and triglycerides in blacks underlies the racial differences in risk translation.

Insulin resistance, beta-cell function, and glucose tolerance in Brazilian adolescents with obesity or risk factors for type 2 diabetes mellitus

OBJECTIVE

To evaluate insulin resistance (IR), beta-cell function, and glucose tolerance in 119 Brazilian adolescents with obesity or risk factors (RF) for type 2 diabetes mellitus (T2DM).

STUDY DESIGN

We analyzed weight (kg), height (m), body mass index (BMI; kg/m(2)), waist (W; cm), acanthosis nigricans (AN), systolic and diastolic blood pressure (SBP and DBP; mm Hg), fasting plasma glucose (FPG), and 2-h plasma glucose (2hPG) on oral glucose tolerance test (OGTT; 1.75 g of glucose/weight), lipid profile [total cholesterol (TC), fractions, and triglycerides (TGs)], fasting insulin (FI) and 2-h insulin on OGTT (2hI-RIA), HOMA-B (%; beta-cell function--HOMA program), HOMA-S (%; insulin sensitivity--HOMA program) and HOMA-IR [fasting plasma insulin (mU/ml)xfasting plasma glucose (mmol/L)/22.5]. Division according to number of RF-family history of T2DM (FHT2DM), obesity, hypertension, dyslipidemia, polycystic ovary syndrome (PCOS), and AN. G1: subjects with no or one RF; G2: subjects with two or more RFs. Statistical data were nonparametrical.

RESULTS

Fasting plasma glucose (G2: 81.6+/-10.2 vs. G1: 79.8+/-9.9 mg/dl) and 2hPG (88.1+/-18.0 vs. 87.0+/-19.9 mg/dl) were not different between G2 (n=67) and G1 (n=52), and all adolescents had normal glucose tolerance (NGT). Fasting insulin (13.0+/-7.9 vs. 7.6+/-3.9 microIU/ml; P<.001) and 2hI (60.2+/-39.1 vs. 38.3+/-40.0 microIU/ml; P<.001), HOMA-B (169.1+/-131.6% vs. 106.1+/-39.9%; P<.001), and HOMA-IR (2.62+/-1.7 vs. 1.52+/-0.8; P<.001) were higher in G2. HOMA-S (92.5+/-59.5% vs. 152.2+/-100.5%; P<.001) was also lower in this latter group.

CONCLUSION

Brazilian adolescents with two or more RFs for the development of T2DM have higher IR and beta-cell function and lower insulin sensitivity. However, adolescents with impaired glucose tolerance (IGT) or DM have not been found, differently from similar studies. Differences in ethnic background, environment, and lifestyle factors may account for this disparity.

Longitudinal study of physiologic insulin resistance and metabolic changes of puberty

Cross-sectional studies have shown that 1) adolescents are insulin resistant compared with prepubertal children and adults, 2) pubertal insulin resistance is likely mediated by growth hormone (GH), and 3) pubertal insulin resistance is associated with increased fat oxidation and decreased glucose oxidation. The aim of this study was to assess the validity of these cross-sectional observations by performing a longitudinal study in normal children during the prepubertal and pubertal periods. Nine healthy, normal weight, prepubertal children underwent hyperinsulinemic-euglycemic and hyperglycemic clamp studies for evaluation of insulin sensitivity and insulin secretion. Children had repeat evaluations during puberty. Consistent with cross-sectional observations, this longitudinal study demonstrated that during puberty: 1) insulin sensitivity decreased by approximately 50%, 2) the decrease in insulin sensitivity was compensated by a doubling in insulin secretion, and 3) the decrease in insulin sensitivity was independent of changes in percentage of body fat. Puberty was associated with increased total body lipolysis and decreased glucose oxidation. A novel observation is the demonstration of approximately 50% decrease in adiponectin levels at the pubertal time point. These metabolic changes are proposed to be partially mediated by increased GH secretion and are consistent with the Randle cycle of competition between glucose and fat oxidation.

Evaluation of family history as a risk factor and screening tool for detecting undiagnosed diabetes in a nationally representative survey population

PURPOSE

We examined the utility of a three-level familial risk stratification system as a screening tool for diabetes in a nationally representative sample of the U.S. adult population.

METHODS

National Health and Nutrition Examination Survey data were used to assess the prevalence and distribution of familial risk for diabetes, the association between three levels of familial risk and undiagnosed diabetes, and the use of familial risk as a screening tool for diabetes, alone and in combination with body mass index and age.

RESULTS

The prevalence of undiagnosed diabetes was 3% and increased with increasing familial risk (average = 2%, moderate = 4%, high = 10%). High familial risk was significantly associated with undiagnosed diabetes (adjusted odds ratio = 4.6; 95% confidence interval: 1.9-11.3). The use of a three-tiered familial risk stratification for diabetes screening yielded higher specificity (94%) and positive predictive value (9.9%) for high familial risk than body mass index > or = 25 (specificity = 38%, positive predictive value = 4.2%). High familial risk and body mass index > or = 25 combined had higher specificity (97%) and positive predictive value (13.4%); the addition of age > or = 45 years further improved positive predictive value (21.0%) without reducing specificity.

CONCLUSIONS

There was a strong and proportional association between familial risk and undiagnosed diabetes, suggesting that a three-tiered assessment of familial diabetes risk may increase the effectiveness of diabetes screening.

Evaluation of glucose intolerance in adolescents relative to adults with type 2 diabetes mellitus

AIM

There is an increasing trend in the prevalence of type 2 diabetes mellitus (DM2) in childhood and adolescence, while positive family history of DM2 and obesity are the most important risk factors. To study the influence of family history and obesity on glucose intolerance in our country was the aim of this study.

STUDY DESIGN AND METHODS

A total of 105 children and adolescents aged 10-18 years (mean 13.3 +/- 2.5 years) were included in the study. All children and adolescents were divided into three groups according to positive family history of DM2 and obesity, and an oral glucose tolerance test (OGTT) was performed for all. Prediabetes was defined as impaired glucose tolerance (IGT) and/or impaired fasting glucose (IFG). Insulin secretion and insulin resistance were estimated using the insulinogenic index; and the homeostatic model assessment for insulin resistance (HOMA-IR) and Matsuda index, respectively.

RESULTS

The prevalence of prediabetes was 15.2% in the whole group, while it was 25.5% in obese children who also had a positive family history of DM2. The frequency of hyperinsulinism was 57.1% in all groups. Prediabetic children had significant insulin resistance (HOMA-IR 11.5 +/- 7.1 and 4.1 +/- 6.4, respectively, p = 0.034).

CONCLUSIONS

Obesity and glucose intolerance are also a problem in developing countries. The risk of prediabetes in children is highest in obese children who also have a positive family history of DM2. There is a need for a lifelong preventive program starting in childhood to avoid DM2 and decrease cardiovascular risk factors

Prevention and treatment of type 2 diabetes in youth

Parallel to the increase in obesity worldwide, there has been a rise in the prevalence of type 2 diabetes mellitus (T2DM) in children and adolescents. The etiology of T2DM in youth, similar to adults, is multifactorial including genetic and environmental factors, among them obesity, sedentary lifestyle, family history of the disease, high-risk ethnicity and insulin resistance phenotype playing major roles. Treatment of T2DM should not have a glucocentric approach; it should rather target improving glycemia, dyslipidemia, hypertension, weight management and the prevention of short- and long-term complications. Prevention strategies, especially in high-risk groups, should focus on environmental change involving participation of families, schools, the food and entertainment industries and governmental agencies. Presently, limited pharmacotherapeutic options need to be expanded both for childhood T2DM and obesity. The coming decades will prove very challenging for healthcare providers battling socioeconomic waves conducive to obesity and T2DM. Evidence-based research and clinical experience in pediatrics, possibly modeled after adult trials, need to be developed if this public health threat is to be contained.

Insulin resistance in children and adolescents

IR is hypothesized to be the important pathophysiologic link between adiposity and future development of type 2 diabetes and cardiovascular disease. A variety of methods for measuring IR have been validated in children, from the gold-standard hyperinsulinemic euglycemic clamp, to simple fasting measures based on fasting insulin and glucose levels. Studies have shown that there are a number of important risk factors for IR in children, including adiposity and visceral adiposity, race/ethnicity, puberty, a family history of type 2 diabetes, sex, and being small for gestational age or prematurity. However, obesity represents the critical risk factor for IR in children. Greater than 50% of obese adolescents in the US have IR. Formal assessment of IR in obese children may represent an important strategy for improving the efficacy of pharmacologic therapy for weight loss and chronic disease prevention.

Cardiorespiratory fitness in youth: relationship to insulin sensitivity and beta-cell function

OBJECTIVE

We examined whether the relationship between cardiorespiratory fitness (CRF) and insulin sensitivity (IS)/secretion is independent of adiposity in healthy African-American (n = 65) and white (n = 57) youth.

RESEARCH METHODS AND PROCEDURES

IS and beta-cell function were evaluated by a 3-hour hyperinsulinemic-euglycemic and a 2-hour hyperglycemic (12.5 mM) clamp, respectively. Total fat was measured by DXA and abdominal fat with computed tomography. CRF (peak volume of oxygen) was measured using a graded maximal treadmill test.

RESULTS

Independent of race, CRF was inversely (p < 0.05) related to total and abdominal fat, fasting insulin and first phase insulin secretion, and positively (p < 0.05) related to IS. When subjects were categorized into low (< or = 50th) and high (> 50th) CRF groups, IS was significantly (p < 0.05) higher in the high compared with the low CRF group independently of race. Furthermore, first and second phase insulin secretion were lower (p < 0.05) in the high CRF group in comparison with the low CRF group in both races. However, in multiple regression analyses CRF was not (p > 0.05) an independent predictor of IS and acute insulin secretion after accounting for total adiposity.

DISCUSSION

Our findings demonstrate that low CRF is associated with decreased IS compensated by higher insulin secretion in both African-American and white youth. However, this relationship disappears after adjusting for differences in adiposity, suggesting that the association between fitness and IS is mediated, at least in part, through fatness.

Waist circumference is an independent predictor of insulin resistance in black and white youths

OBJECTIVES

We examined how well waist circumference (WC) reflects total and abdominal fat and whether WC predicts insulin resistance independent of body mass index (BMI) percentile in youths.

STUDY DESIGN

Body composition was measured by dual-energy x-ray absorptiometry and abdominal adiposity by computed tomography. Insulin sensitivity was measured by the hyperinsulinemic-euglycemic clamp.

RESULTS

Both BMI percentile and WC were significantly associated (P < .01) with total and abdominal fat and insulin sensitivity. WC remained a significant (P < .01) correlate of total and abdominal fat and insulin sensitivity after controlling for BMI percentile. By contrast, BMI percentile did not remain a significant correlate of visceral fat and markers of insulin resistance after controlling for WC. Without exception, WC explained a greater variance in abdominal fat and metabolic profiles than did BMI percentile.

CONCLUSIONS

Our findings suggest that the prediction of health risks associated with obesity in youths is improved by the additional inclusion of WC measure to the BMI percentile. Such observations would reinforce the importance of including WC in the assessment of childhood obesity to identify those at increased metabolic risk due to excess abdominal fat.

Understanding the development and prevention of type 2 diabetes in youth (part 1)

The prevalence of being at risk of overweight, overweight, pre-diabetes, and type 2 diabetes is increasing in the United States in youth. Primary care providers must understand how the emerging epidemic of type 2 diabetes developed during the past several decades to accurately diagnose it in young patients. Primary, secondary, and tertiary prevention interventions are needed to address the emerging epidemic of type 2 diabetes in youth. Primary prevention involves delaying the development of type 2 diabetes by reducing the prevalence of overweight. Secondary prevention is aimed at preventing those with pre-diabetes from developing diabetes, and tertiary prevention is aimed at preventing the complications of type 2 diabetes.

Type 2 diabetes mellitus in youth: the complete picture to date

Type 2 diabetes mellitus is a heterogeneous condition in which the clinical manifestation of hyperglycemia is a reflection of the impaired balance between insulin sensitivity and insulin secretion. Clinical experience and research in youth type 2 diabetes mellitus are in an early stage because of the relative novelty of the condition in pediatrics. This article discusses the amassed information in type 2 diabetes mellitus of youth to date with respect to the epidemiology, pathophysiology, risk factors, clinical presentation, screening, and management strategies.

Type 2 diabetes mellitus in children and adolescents

Over the last decade, there has been an alarming increase of Type 2 diabetes mellitus (T2DM) in youths, concomitant with the rise of obesity in this age group. T2DM is a progressive disease with a gradual increase in insulin resistance associated later with a decline in insulin secretion with fasting hyperglycemia. Prevalence of T2DM in children is mostly linked to some risk factors: obesity and sedentary lifestyle, puberty, membership of ethnic minorities, features of insulin resistance, family history of T2DM, female gender and perinatal factors. Prevention is essential and can be considered a public health approach directed to the general population. Treatment of T2DM in youth is complex and based on different strategies: diet, exercise and pharmacotherapy. An appropriated intervention program must be started early, in order to prevent or retard the progression of the disease and associated comorbidities.

Type 2 diabetes in children and youth

The number of children and youth diagnosed with type 2 diabetes has increased dramatically over the last decade. Much still needs to be learned about why this epidemic is occurring presently with regard to other environmental factors that might promote insulin resistance and beta-cell failure. The TODAY trial will help to determine the best treatment strategies to improve glycemia, reduce complications, and ameliorate insulin resistance and beta-cell failure. As type 2 diabetes emerges as a worldwide public health problem, improved care for affected youth must be coupled with a focus on prevention.

Comparison of maximal oxygen consumption between obese black and white adolescents

The purpose of this investigation was to determine whether maximal oxygen consumption (VO2max) differed between clinically obese black and white children and if a difference existed to determine whether it was related to hematological profiles and/or physical activity/inactivity levels. Twenty-three black and 21 white adolescents were matched for age, BMI, and Tanner stage (II-V). Body composition was determined by DEXA and CT scan. Daily physical activity/inactivity was assessed by questionnaire. VO2max was assessed using the Bruce treadmill protocol. Black participants had significantly lower VO2max and VO2maxFFM values when compared with white adolescents (26.1 +/- 4.2 versus 29.9 +/- 3.1 mL . kg(-1) . min(-1); 48.3 +/- 8.8 versus 55.6 +/- 5.2 mL . kgFFM(-1) . min(-1), respectively). Black adolescents also had significantly lower Hb concentrations ([Hb]) than white children (12.7 +/- 1.3 versus 13.4 +/- 0.7 g/dL). Black adolescents were more physically inactive than their white peers. VO2max correlated with [Hb] for the combined groups. Obese black adolescents had lower VO2max compared with white children and this difference was explained, in part, by the lower [Hb] observed in the black participants. Further investigations should study Hb flow rate (a function of [Hb] . maximal cardiac output) and physical activity/inactivity patterns in obese black and white children as it relates to VO2max.

Basic approach to managing hyperglycemia for the nonendocrinologist

The prevalence of type 2 diabetes mellitus is growing rapidly worldwide. Reducing the complications of diabetes requires aggressive management of multiple risk factors, including elevated blood pressure, abnormal plasma lipid levels, and elevated plasma glucose. Fortunately, numerous agents are available to control these risk factors. This review discusses the therapeutic options in managing hyperglycemia, including lifestyle, oral agents, and insulin.

Frequency of abnormal carbohydrate metabolism and diabetes in a population-based screening of adolescents

OBJECTIVE

To document the frequency of glucose intolerance in adolescents in a population-based study of primarily African-American/Non-Hispanic whites in an urban-suburban school district.

STUDY DESIGN

Measurement of fasting and 2-hour post-glucose load plasma glucose concentrations.

RESULTS

Carbohydrate intolerance (either impaired fasting glucose, impaired glucose tolerance, or both) was identified in 8.0%, near-diabetes (1 fasting glucose > or = 126 mg/dL [7.0 mmol/L] and/or 2-hour glucose > or = 200 mg/dL [11.1 mmol/L]) in 0.3%, and diabetes in 0.36% (type 1A = 0.24%; type 2 = 0.08%; undiagnosed type 2 = 0.04%). A model for abnormal carbohydrate metabolism was constructed with regression analysis in the Carbohydrate Intolerance (CI)/near-diabetes group and with logistic regression in the entire study population. Risk factors for the development of CI/near-diabetes included having a 1 unit increase in body mass index (BMI) z-score and either being non-Hispanic white or in the pubertal group. Increased fasting glucose correlated with having puberty and decreased BMI z-score, whereas 2-hour glucose correlated with increased BMI z-score. By using National Health and Nutrition Survey (NHANES) III (1988-1994) definitions, impaired fasting glucose was present in 2.0% in this study versus 1.7% (NHANES III).

CONCLUSION

The prevalence of CI/near-diabetes was 8.3%. Undiagnosed diabetes mellitus was rare. One third of adolescents with diabetes mellitus could be classified as having type 2 diabetes mellitus. The adult model of the progression of insulin resistance to type 2 diabetes mellitus in adolescents may be valid. Despite the increase in the overweight population since NHANES III, abnormalities in glucose metabolism have not changed significantly.

Racial and etiopathologic dichotomies in insulin hypersecretion and resistance in obese children

OBJECTIVES

To assess insulin dynamics to oral glucose tolerance testing in obese children, denoting individual contributions of insulin hypersecretion versus resistance to racial and etiopathogenetic specificity.

STUDY DESIGN

We performed 3-hour oral glucose tolerance testing in 113 nondiabetic obese children (age 13.6 +/- 3.1 years; 41 male, 78 female; 37 black, 41 white; 35 with central nervous system [CNS] insult). The corrected insulin response (CIRgp; measuring beta-cell secretion) and the composite insulin sensitivity index (CISI) were computed and log-transformed, and each was modeled in terms of the other, plus race/etiology, age, sex, body mass index z score, glucose tolerance, pubertal status, and geographic location.

RESULTS

A scatterplot of logCIRgp versus logCISI showed that racial and etiopathogenetic groups plotted in different areas. CISI (controlled for CIRgp and other variables) was only 13% lower in blacks than in whites ( P = .32). Conversely, CIRgp (controlled for CISI and other variables) was 49% higher in blacks ( P = .028). CNS insult exhibited a 40% higher CIRgp ( P = .054) and 11% higher CISI ( P = .42) than intact white subjects.

CONCLUSIONS

Insulin hypersecretion and resistance are distinct phenomena in childhood obesity. Insulin hypersecretion appears to be the more relevant insulin abnormality both in obese blacks and in CNS insult.