Hyperinsulinaemia and abnormalities in hepatic insulin extraction commonly coexist in ethnic groups with severe insulin resistance. Therefore, we compared the effects of ethnicity on glucose/insulin/C-peptide dynamics, hepatic insulin extraction, and insulin sensitivity in healthy black (n = 32) and white (n = 30) Americans. Standard oral glucose tolerance test (OGTT) and tolbutamide-modified, frequently sampled, intravenous glucose tolerance (FSIVGT) tests were performed in each subject. Insulin sensitivity index (S1)) was calculated using the MINIMOD method described by Bergman et al. Basal and post-stimulation hepatic insulin extraction were calculated by the molar ratios of C-peptide and insulin concentrations during the basal steady state and areas under the post-stimulation hormone curves, respectively. Apart from a slightly greater mean serum glucose peak response after oral glucose in the whites, mean glucose levels were identical in the blacks and whites during both stimulations. In contrast, serum insulin levels at basal and during both stimulations were significantly greater (2-3 fold) in the blacks than whites. However, the corresponding C-peptide responses were identical in both groups. The basal and postprandial hepatic insulin extraction were 33% and 45% lower in the blacks when compared to whites, respectively. The mean S1 was significantly (p < 0.02) lower in the blacks (4.93 +/- 0.46) than the whites (7.17 +/- 0.88 x 10(-4).min-1 (mU l-1)-1). We conclude that ethnicity may be a major determinant of the mechanism of peripheral hyperinsulinaemia and insulin insensitivity in black and white Americans.

Purpose Obesity is an independent risk factor in trauma-related morbidity in adults. The purpose of this study was to investigate the effect of obesity in the pediatric trauma population. Methods All patients (6-20 years) between January 2004 and July 2007 were retrospectively reviewed and defined as non-obese (body mass index [BMI] <95th percentile for age) or obese (BMI ≥95th percentile for age). Groups were compared for differences in demographics, initial vital signs, mechanisms of injury, length of stay, intensive care unit stay, ventilator days, Injury Severity Score, operative procedures, and clinical outcomes. Results Of 1314 patients analyzed, there were 1020 (77%) nonobese patients (mean BMI = 18.8 kg/m2) and 294 (23%) obese patients (mean BMI = 29.7 kg/m2). There was no significant difference in sex, heart rate, length of stay, intensive care unit days, ventilator days, Injury Severity Score, and mortality between the groups. The obese children were significantly younger than the nonobese children (10.9 ± 3.3 vs 11.5 ± 3.5 years; P = .008) and had a higher systolic blood pressure during initial evaluation (128 ± 17 vs 124 ± 16 mm Hg, P < .001). In addition, the obese group had a higher incidence of extremity fractures (55% vs 40%; P < .001) and orthopedic surgical intervention (42% vs 30%; P < .001) but a lower incidence of closed head injury (12% vs 18%; P = .013) and intraabdominal injuries (6% vs 11%; P = .023). Evaluation of complications showed a higher incidence of decubitus ulcers (P = .043) and deep vein thrombosis (P = .008) in the obese group. Conclusion In pediatric trauma patients, obesity may be a risk factor for sustaining an extremity fracture requiring operative intervention and having a higher risk for certain complications (ie, deep venous thrombosis [DVT] and decubitus ulcers) despite having a lower incidence of intracranial and intraabdominal injuries. Results are similar to reports examining the effect(s) of obesity on the adult population.

Context: Short-term aerobic exercise training can improve whole-body insulin sensitivity in humans with type 2 diabetes mellitus; however, the contributions of peripheral and hepatic tissues to these improvements are not known.Objective: Our objective was to determine the effect of 7-d aerobic exercise training on peripheral and hepatic insulin sensitivity during isoglycemic/hyperinsulinemic clamp conditions. Design: Subjects were randomly assigned to one of two groups. The energy balance group consumed an isocaloric diet consisting of 50% carbohydrate, 30% fat, and 20% protein for 15 d. The energy balance plus exercise group consumed a similar diet over the 15 d and performed 50-min of treadmill walking at 70% of maximum oxygen consumption maximum during the second 7 d of the 15-d study period. Each subject underwent an initial isoglycemic/hyperinsulinemic clamp after 1-wk dietary control and a second clamp after completing the study. Setting:The study was performed at Ohio State University's General Clinical Research Center.Participants: There were 18 obese, mildly diabetic humans included in the study.Intervention: Aerobic exercise training was performed for 7 d. Main Outcome Measures:Whole-body, peripheral, and hepatic insulin sensitivity were measured.Results: Exercise training did not have an impact on peripheral glucose uptake or endogenous glucose production during the basal state or low-dose insulin. Likewise, it did not alter endogenous glucose production during high-dose insulin. However, 1-wk of exercise training increased both whole-body (P Ͻ 0.05) and peripheral insulin sensitivity (P Ͻ 0.0001) during high-dose insulin.Conclusion: Improvements to whole body insulin sensitivity after short-term aerobic exercise training are due to gains in peripheral, not heptic insulin sensitivity. T ype 2 diabetes mellitus (DM) is a metabolic disease characterized by insulin resistance, relative ␤-cell dysfunction, and resultant hyperglycemia that can contribute to the development of both microvascular and macrovascular disease. Despite an apparently strong genetic influence on the development of DM, environmental factors such as obesity and physical inactivity can hasten this process in humans (1-3), while interven-