Exercise alone reduces insulin resistance in obese children independently of changes in body composition.

CONTEXT: The number of obese children with insulin resistance and type 2 diabetes is increasing, but the best management strategy is not clear. OBJECTIVE: The objective of this study was to assess the effect of a structured 8-wk exercise training program on insulin resistance and changes in body composition in obese children. DESIGN: The study was 8 wk of structured supervised exercise intervention with outcome measures before and after the exercise period. SUBJECTS: Fourteen obese children (12.70 +/- 2.32 yr; eight male, six female) with high fasting insulin levels were enrolled into the study. INTERVENTION: INTERVENTION consisted of 8 wk of supervised circuit-based exercise training, composed of three fully supervised 1-h sessions per week. OUTCOME MEASURES: Outcome measures were assessed pretraining program and posttraining program and included insulin sensitivity (euglycemic-hyperinsulinemic clamp studies), fasting insulin and glucose levels, body composition using dual energy x-ray absorptiometry scan, lipid profile, and liver function tests. RESULTS: Insulin sensitivity improved significantly after 8 wk of training (M(lbm) 8.20 +/- 3.44 to 10.03 +/- 4.33 mg/kg.min, P < 0.05). Submaximal exercise heart rate responses were significantly lower following the training (P < 0.05), indicating an improvement in cardiorespiratory fitness. Dual energy x-ray absorptiometry scans revealed no differences in lean body mass or abdominal fat mass. CONCLUSION: An 8-wk exercise training program increases insulin sensitivity in obese children, and this improvement occurred in the presence of increased cardiorespiratory fitness but is independent of measurable changes in body composition.

Increasing body mass index z-score is continuously associated with complications of overweight in children, even in the healthy weight range.

CONTEXT: Overweight/obesity in children is increasing. Incidence data for medical complications use arbitrary cutoff values for categories of overweight and obesity. Continuous relationships are seldom reported. OBJECTIVES: The objective of this study is to report relationships of child body mass index (BMI) z-score as a continuous variable with the medical complications of overweight. DESIGN: This study is a part of the larger, prospective cohort Growth and Development Study. SETTING: Children were recruited from the community through randomly selected primary schools. Overweight children seeking treatment were recruited through tertiary centers. PARTICIPANTS: Children aged 6-13 yr were community-recruited normal weight (n = 73), community-recruited overweight (n = 53), and overweight treatment-seeking (n = 51). Medical history, family history, and symptoms of complications of overweight were collected by interview, and physical examination was performed. Investigations included oral glucose tolerance tests, fasting lipids, and liver function tests. MAIN OUTCOME MEASURE: Adjusted regression was used to model each complication of obesity with age- and sex-specific child BMI z-scores entered as a continuous dependent variable. RESULTS: Adjusted logistic regression showed the proportion of children with musculoskeletal pain, obstructive sleep apnea symptoms, headaches, depression, anxiety, bullying, and acanthosis nigricans increased with child BMI z-score. Adjusted linear regression showed BMI z-score was significantly related to systolic and diastolic blood pressure, insulin during oral glucose tolerance test, total cholesterol, high-density lipoprotein, triglycerides, and alanine aminotransferase. CONCLUSION: Child's BMI z-score is independently related to complications of overweight and obesity in a linear or curvilinear fashion. Children's risks of most complications increase across the entire range of BMI values and are not defined by thresholds.

Glucose requirements to maintain euglycemia after moderate-intensity afternoon exercise in adolescents with type 1 diabetes are increased in a biphasic manner.

CONTEXT: Exercise increases the risk of hypoglycemia in type 1 diabetes. OBJECTIVE: This study aimed to investigate how the amount of glucose required to prevent an exercise-mediated fall in glucose level changes over time in adolescents with type 1 diabetes. SETTING: The study took place at a tertiary pediatric referral center. DESIGN, PARTICIPANTS, AND INTERVENTION: Nine adolescents with type 1 diabetes mellitus (five males, four females, aged 16 +/- 1.8 yr, diabetes duration 8.2 +/- 4.1 yr, hemoglobin A1c 7.8 +/- 0.8%, mean +/- SD) were subjected on two different occasions to a rest or 45 min of exercise at 95% of their lactate threshold. Insulin was administered iv at a rate based on their usual insulin dose, with similar plasma insulin levels for both studies (82.1 +/- 19.0, exercise vs. 82.7 +/- 16.4 pmol/liter, rest). Glucose was infused to maintain euglycemia for 18 h. MAIN OUTCOME MEASURES: Glucose infusion rates required to maintain euglcycemia and levels of counterregulatory hormones were compared between rest and exercise study nights. RESULTS: Glucose infusion rates to maintain stable glucose levels were elevated during and shortly after exercise, compared with the rest study, and again from 7-11 h after exercise. Counterregulatory hormone levels were similar between exercise and rest studies except for peaks in the immediate postexercise period (epinephrine, norepinephrine, GH, and cortisol peaks: 375.6 +/- 146.9 pmol/liter, 5.59 +/- 0.73 nmol/liter, 71.9 +/- 14.8 mIU/liter, and 558 +/- 69 nmol/liter, respectively). CONCLUSIONS: The biphasic increase in glucose requirements to maintain euglycemia after exercise suggests a unique pattern of early and delayed risk for nocturnal hypoglycemia after afternoon exercise.

Increase in type 2 diabetes in children and adolescents in Western Australia.

OBJECTIVES: To document diagnosis rates of type 2 diabetes mellitus in children and adolescents in Western Australia over the past 12 years, the clinical characteristics of these patients and any comorbidities. DESIGN: Review of a prospectively recorded diabetes database. SETTING: Tertiary paediatric referral centre (the only such centre in WA). PATIENTS: All children and adolescents aged < 17 years diagnosed with type 2 diabetes between 1990 and 2002 and managed by Princess Margaret Hospital Diabetes Unit. MAIN OUTCOME MEASURES: Anthropometric and demographic data; glycohaemoglobin (HbA(1c)) level; blood pressure; lipid levels; presence of acanthosis nigricans. RESULTS: 43 patients (15 males and 28 females) were diagnosed with type 2 diabetes. Age (SD) at diagnosis was 13.6 (1.8) years. The rate of diagnosis has been progressively increasing (average annual increase in the unadjusted overall rates of type 2 diabetes was 27%). Twenty-three patients (53%) were of Indigenous origin and 18 (42%) resided in rural areas. The mean (SD) HbA(1c) level at diagnosis was 10.0% (3.2%). Seventy-two per cent of patients had acanthosis nigricans, 59% had hypertension, and 24% had hyperlipidaemia. CONCLUSIONS: There has been an increase in the diagnosis rate of type 2 diabetes in children and adolescents in WA. Comorbidities are frequent.