Longitudinal study of endothelial function in children with type 1 diabetes mellitus

Patients with type 1 diabetes (T1DM) have increased risk of vascular complications which development is related to the duration of diabetes and the degree of glycemic control. Impaired flow-mediated dilation (FMD) has been detected in children with diabetes, and we previously reported that a good glycemic control gets a better vascular function.Aim of our study was to evaluate longitudinally changes of FMD in T1DM patients.Thirty two children (18 male, 14 female; 11.6±3.33 yr.) with T1DM (duration of disease 49.1±39.5 months) entered the study; lipid profile, HbA1c and FMD were determined at the beginning and after 30.3±7.42 months. Vascular function was assessed by measurements of endothelium-dependent vasodilation of the brachial artery using high-sensibility ultrasound system. FMD was expressed as percentage change of diameter following reactive hyperemia from baseline.No significantly change of HbA1c (7.99±1.06 vs 8.12±1.11%; p=0.28) and FMD (6.41±10.6 vs 2.57±9.01%; p=0.09) was demonstrated; however, half of the children had FMD <7% while at the follow-up abnormal FMD was demonstrated in 75% of cases. No correlation was demonstrated between FMD and lipid profile, HbA1C or duration of the disease. Considering the glycemic control during follow-up, no difference was shown in FMD values between children with poor (>8%) and good HbA1c (≤8%) (2.69±8.55 vs 2.33±10.2%; p=0.91), despite significantly difference in the months from diagnosis (91.6±42.7 vs 56.2±26.1 months; p=0.01). According to sex, no difference of age, months of disease, HbA1c and FMD was revealed, while longitudinally boys had significantly lower FMD than girls (-0.95±8.15 vs 7.10±8.19%; p=0.009).Our data show that after several years patients had a worse FMD not apparently related to glycemic control or to duration of T1DM. This difference, more evident in males, suggests that further studies are needed to better understand which factors are involved in functional changes of endothelial dysfunction.