Insulin sensitivity in Type 1 diabetic children and adolescents.

AIM: To estimate insulin sensitivity in Type 1 diabetic children and adolescents, and assess the relationship between insulin sensitivity and clinical markers of adiposity and parameters of the metabolic syndrome. METHODS: A total of 202 patients aged 8-18 years with Type 1 diabetes and disease duration 1.5-15 years participated. Insulin sensitivity was estimated by glucose uptake during an euglycaemic-hyperinsulinaemic clamp and was calculated as the average amount of glucose (M(lbm) = mg/kg(lbm)/min) required to maintain euglycaemia. Blood pressure, glycated haemoglobin (HbA(1c)) and lipid concentrations were measured. RESULTS: The M(lbm )value ranged from 4.14 to 25.25 mg/kg(lbm)/min (mean 9.81 +/- 3.34 mg/kg(lbm)/min). There was a significant relationship between M value and patients' age (r = -0.38, P < 0.0001). Insulin sensitivity decreased significantly with the onset of puberty; hence, it was significantly lower in pubertal and post-pubertal adolescents. Girls were significantly more insulin resistant than boys (9.01 +/- 0.32 vs. 10.43 +/- 0.29 mg/kg(lbm)/min, P = 0.005). Insulin sensitivity correlated with body mass index (r = -0.29, P < 0.001), waist circumference (r = -0.35, P < 0.001), triceps skin fold (r = -0.17, P = 0.018), subscapular skin fold (r = -0.23, P = 0.001) and body fat (r = -0.19, P = 0.006). There was a relationship between M(lbm) value, cholesterol (r = -0.18, P = 0.012), high-density lipoprotein cholesterol (r = 0.15, P = 0.035), low-density lipoprotein cholesterol (r = -0.22, P = 0.002), triglycerides (r = -0.32, P < 0.001) and systolic blood pressure (r = -0.15, P = 0.029). Insulin resistance was related to HbA(1c) (r = -0.18, P = 0.012). Additionally, there was a correlation between M(lbm) value and insulin dose. CONCLUSIONS: Children and adolescents with Type 1 diabetes mellitus have a very wide range of insulin sensitivity, which is determined by sex, age, amount of adipose tissue and glycaemic control.

Renin and hemodynamic responses to exercise in borderline hypertensives.

OBJECTIVE: In this study, we examined the relationship between baseline plasma renin (REN) and hemodynamic variables during recovery from aerobic exercise in 10 Caucasian (C) and 10 African-American (AA) borderline hypertensive females. METHODS: Subjects attended three preliminary sessions and an experimental session in which treadmill walking was performed for 40 minutes at a moderate intensity. During this session, blood was drawn at baseline prior to exercise and immediately following. Blood pressure and other hemodynamic variables were recorded at rest before exercise and for 2 hours afterwards. The average difference from baseline during the two hour recovery period was calculated for each variable and used as the dependent variable in a multiple regression analysis. RESULTS: For mean arterial pressure and cardiac output, the regression slopes did not differ between AA and C. However, during recovery, the average difference from baseline for systemic vascular resistance (SVR) increased in AA but decreased in C. CONCLUSION: In conclusion, REN had a significant effect on SVR but no effect on the other hemodynamic variables during recovery from aerobic exercise. It appears as if the peripheral vasculature in AA may be more sensitive than in C to the vasoconstrictive effects of the renin angiotensin system.