Impaired Endothelial Function in Preadolescent Children With Type 1 Diabetes

GHUFRAN S. BABAR MSC HANAA ZIDAN MICHAEL E. WIDLANSKY EMON DAS RAYMOND G. HOFFMANN PHD MARWAN DAOUD PHD RAMIN ALEMZADEH OBJECTIVEWe evaluated the prevalence of endothelial dysfunction as measured by flowmediated dilatation (FMD) of the brachial artery and carotid intima-media thickness (c-IMT) in relationship to vascular inflammatory biomarkers in preadolescent children with type 1 diabetes. RESEARCH DESIGN AND METHODSWe studied 21 type 1 diabetic children (aged 8.3 6 0.3 years with diabetes duration of 4.3 6 0.4 years) and 15 group-matched healthy siblings (aged 7.6 6 0.3 years). Fasting plasma glucose (FPG), lipid profile, HbA1c, high-sensitivity C-reactive protein (hs-CRP), fibrinogen, homocysteine, and erythrocyte (red blood cell [RBC]) folate were evaluated in all subjects. Each subject underwent c-IMT and brachial artery FMD percentage (FMD%) measurements using high-resolution vascular ultrasound. RESULTSType 1 diabetic children had higher FPG (173.4 6 7.9 mg/dL vs. 81.40 6 1.7 mg/ dL; P , 0.0001), HbA1c (8.0 6 0.2% vs. 5.0 6 0.1%; P , 0.0001), and hs-CRP (1.8 6 0.3 vs. 0.70 6 0.2; P = 0.017) than control children without significant differences in BMI, homocysteine, and fibrinogen levels; RBC folate content; and c-IMT between the groups. Children with type 1 diabetes had lower FMD% than control children (7.1 6 0.8% vs. 9.8 6 1.1%; P = 0.04), whereas c-IMT did not differ between groups. CONCLUSIONSPreadolescent children with type 1 diabetes and mean diabetes duration of 4 years displayed evidence of low-intensity vascular inflammation and attenuated FMD measurements. These data suggest that endothelial dysfunction and systemic inflammation, known harbingers of future cardiovascular risk, are present even in preadolescent children. - P two to four times the risk of deatients with type 1 diabetes have veloping cardiovascular disease relative to the nondiabetic population (1). Type 1 diabetes causes endothelial dysfunction and early atherosclerosis (2). Endothelial dysfunction and alterations in vascular structure are early indicators of future cardiovascular events (3). Berenson et al. (4) observed that atherosclerotic changes begin much earlier than the appearance of clinical disease, as shown by young-adult autopsy findings. Their work prompted multiple small studies (59) that have consistently demonstrated abnormal vascular homeostasis and inflammation in children with type 1 diabetes. These studies have consistently demonstrated that children and adolescents with type 1 diabetes have endothelial dysfunction relative to nondiabetic age-matched control children, as measured by flow-mediated dilation (FMD) in the brachial artery (5,7,8). c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c In addition, adverse carotid remodeling, known to portend future cardiovascular risk, also has been consistently reported in this population (1013). However, these studies have not rigorously assessed pubertal status, and it remains unknown whether the adverse effects of type 1 diabetes on vascular homeostasis are apparent even during the preadolescent stage. We hypothesized that prepubertal children with type 1 diabetes would also manifest early signs of abnormal vascular homeostasis, including impaired endothelial function, increased carotid intima-media thickness (c-IMT), and elevated circulating markers of inflammation. We evaluated our hypothesis in a cross-sectional study of type 1 diabetes and healthy matched sibling control subjects. RESEARCH DESIGN AND METHODSTwenty-one prepubertal children with type 1 diabetes, aged 8.5 6 0.3 years (diabetes duration of 4.3 6 0.3 years), were recruited from the Childrens Hospital of Wisconsin Diabetes Clinic, which is affiliated with the Medical Col lege of Wisconsin. Children with type 1 diabetes were either on multiple daily insulin, consisting of bedtime insulin glargine and premeal aspart insulin, or continuous subcutaneous insulin infusion (CSII) with insulin aspart. We reviewed 2-week, seven-point, self-monitored blood glucose logs to determine mean blood glucose and SDs as well as rates of moderate (blood glucose ,60 mg z dL21 z week21) or severe hypoglycemia (blood glucose ,50 mg z dL 21 z week21 with altered mental status). In addition, 15 group-matched healthy siblings of the diabetic cohort were recruited as control subjects. Inclusion criteria consisted of prepubertal children aged 69 years. Exclusion criteria included known dyslipidemia, hypertension, microvascular complications, anemia (hemoglobin ,11.0 g/dL), congenital heart disease, allergy to ultrasound gel, or family history of hypercholesterolemia or premature cardiovascular disease. The study protocol was approved by the Childrens Hospital of Wisconsin Institutional Review Board. Informed consent and assent was obtained from the study parents or guardians and the subjects. Laboratory studies Peripheral venous blood samples were obtained to determine the complete blood-count plasma glucose, HbA1c, lipids, high-sensitive C-reactive protein (hs-CRP), fibrinogen, chemistry panel, homocysteine, and erythrocyte folate (red blood cell [RBC] folate) between 0800 h and 1000 h after an overnight 12-h fast. The study procedures were rescheduled if the patients had a self-monitored blood glucose $200 mg/dL or ,80 mg/dL on the morning of the study day. Each subject had breakfast after the completion of all studies. Children with type 1 diabetes received their bolus insulin aspart doses according to their home regimen. Complete blood-count testing was done on the Abbott automated Cell-Dyn instrument (probably the 4000 model). Fasting plasma glucose (FPG) concentrations were measured with a Glucose Analyzer II (Beckman Instruments, Brea, CA), using a glucose oxidase procedure. Replicate readings were repeated to within 3 mg/dL in triplicates. Fasting plasma triglyceride, total cholesterol, HDL cholesterol, and LDL cholesterol levels were determined by spectrophotometry using kits from Stanbio Laboratory (San Antonio, TX), Roche-Boehringer (Indianapolis, IN), Roche-Boehringer (after phosphotungstic acid/MgCl 2 precipitation), and Trinity Biotech (Berkeley Heights, NJ), respectively. All determinations were performed in triplicates. Quality controls were performed to assure stability and reliability of the assays. The intra-assay and interassay coefficients of variation (CVs) for the lipid analyses were 4.7 and 5.3% for triglycerides, 5.5 and 6.7% for cholesterol, 5.7 and 6.1% for HDL cholesterol, and 6.9 and 7.5% for LDL cholesterol, respectively. hs-CRP was determined using a solidphase enzyme-linked immunosorbent assay from MP Biomedicals (West Chester, PA), with a sensitivity of 0.1 mg/L and an intraassay CV ranging from 4.1 to 2.3% with increasing concentrations. Plasma fibrinogen was determined by the Clauss method (Quest Diagnostics, Nichols Institute, San Clemente, CA), with intraassay and interassay CVs of 2.6 and 4 (...truncated)