Endocrine Abstracts

Objective: Diabetes mellitus is characterized by vascular complications associated with arterial thickening. Although strict glycaemic control is clinically beneficial, limited or no evidence exists as to whether arterial damage is positively related to blood glucose levels and variability.

Methods: Study purpose was to asses the relationship between arterial thickness and 24 h mean and S.D. of blood glucose in type 1 diabetes. Fifteen type 1 diabetic patients aged 39±1 years (means±S.E.M.) were enrolled; diabetes aged for 18 years (means). Patients were all normotensive (blood pressure, 128±4/75±2 mmHg) and devoided of clinically evident macro and microvascular complications. Average fasting blood glucose was 160±19.26 mg/dl while Hb1Ac was 7.8±0.35%. Twenty-four hours blood glucose was measured over 24 h every 5 min by a glucometer. The S.D. of blood glucose levels over the 24 h was used as an index of blood glucose variability. Arterial stiffness was measured in two manners: 1) carotido-femoral pulse wave velocity (cfPWV) (Complior), 2) arterial diameter changes/pulse pressure (Reneman Formula, CarDist) the former being measured by an echo-tracking device and the later by a tonometer (pulsepen). Common Carotid artery IMT was measured by standard ecocolor Doppler, 3 cm under bifurcation.

Results: CarDist (4.0±0.4, 1/mmHg 10⁻²), cfPWV (10.1±0.6 m/s) and IMT (0.54±0.02 mm) showed no correlation with glycated hemoglobine. Only CarDist significantly correlated with fasting blood glucose (r=0.57, P<0.02). IMT shows no relationship with mean blood glucose both when assessed in the clinical setting and when averaged over the 24 h. In contrast, there was a direct relationship between the IMT value and the standard deviation of 24 h mean blood glucose (r=0.4, Spearman correlation, P<0.05).

Conclusions: In type 1 diabetes 24 h variability values of blood glucose seem to be a more important determinant of large artery structural alteration than fast and mean blood glycaemia.