Progression of the Carotid Artery Intima-Media Thickness in Young Patients With Type 1 Diabetes

Cross-sectional studies of the combined intima-media wall thickness (IMT) of the carotid arteries performed in type 1 diabetic patients show partly contradictory results with regard to variables that are associated with the IMT. Therefore, we observed the IMT progression in a longitudinal study with two follow-ups: 1) after 2–3 years (mean 2.5 ± 0.4); and 2) after 4–8 years (mean 6.3 ± 1.4).

A total of 65 type 1 diabetic patients (24 men, 41 women) with ≤40 years of age and a diabetes duration of ≥2 years at baseline were included. Recruitment, characteristics of patients at baseline and the methods used, including ultrasound procedures, have been reported elsewhere (1).

The annual progression rate (APR) of each patient was calculated using the difference of the IMT values at the baseline and the follow-up examinations, divided by the time (in years) between these examinations.

The IMT was significantly higher at both follow-up examinations (0.65 ± 0.14 and 0.70 ± 0.19 mm, respectively) than the baseline measurement (0.57 ± 0.13 mm; mean ± SD; P < 0.001). The mean APR was 0.036 mm/year until the first follow-up and 0.020 mm/year until the second follow-up, and it was significantly correlated with these baseline parameters: age, hypertension, systolic blood pressure, ACE inhibitor therapy (all P < 0.001), albumin excretion rate, nephropathy (stage IV and overall), and smoking (P < 0.05). In a multiple linear regression analysis, besides age, only hypertension as a categorical variable was an independent predictor of IMT progression. This was also the case for women when both sexes were analyzed separately, but in men the only independent predictor of APR was nephropathy stage IV.

Compared with the baseline examination, the HbA_1c value was significantly lower (7.9 ± 1.8 vs. 8.8 ± 2.5%, P < 0.05) at the time of the second follow-up, and systolic (131 ± 19 vs. 122 ± 16 mmHg, P < 0.01) and diastolic blood pressure (83 ± 12 vs. 75 ± 11 mmHg, P < 0.001) were significantly higher. The lipids remained unchanged, except for HDL cholesterol, which increased significantly (63 ± 21 vs. 51 ± 18 mg/dl, P < 0.05). Significantly more patients presented with hypertension at the second follow-up (34 vs. 13%, P < 0.05), compared with the baseline examination, and the frequency of nephropathy (35 vs. 25%), retinopathy (49 vs. 31%), and plaques (34 vs. 21%) also increased without reaching significance.

For young type 1 diabetic patients, diabetes seems not to be the main risk for IMT progression (while a better metabolic control could have a retarding effect on it). Hypertension plays a major role, especially in women, whereas advanced nephropathy as a diabetes-specific risk was confirmed in men only. These results are in concordance with our previous findings (2) but still have to be regarded with caution because of the relatively small number of included patients.