Progression of large artery structural and functional alterations in Type I diabetes

Type I (insulin-dependent) diabetes mellitus is accompanied by reduced arterial distensibility and increased arterial wall thickness even in normotensive subjects with no micro-macrovascular complications. It is not known whether, and how fast, these subclinical markers of vascular damage develop over time.

We measured arterial wall distensibility in radial, common carotid artery and abdominal aorta in 60 normotensive patients (aged 35.0 +/- 1.2 years, means +/- SE) with Type I diabetes with no microvascular or macrovascular complications and in 20 healthy control subjects matched for age. Arterial distensibility was determined by continuous measurements of arterial diameter through echotracking techniques and by using either the Langewouters (radial artery) or the Reneman formula (carotid artery and aorta). The same echotracking techniques allowed us to ascertain the radial and carotid artery wall thickness. Data were collected before and after 23 +/- 1 months.

In the first study, carotid artery distensibility was similar but radial artey and aortic distensibility was less (p < 0.01) in patients with diabetes than in control subjects (-39 % and 25 % respectively). This was accompanied by an increase (p < 0.01) in both radial (42 %) and carotid artery wall thickness (46 %). After 23 +/- 1 months diabetic subjects showed a further reduction in arterial distensibility (radial-12 %, p < 0.05; carotid-8 %, NS; aorta-20% p < 0.05) and an increase in arterial wall thickness (radial + 15 %; carotid 14%, p < 0,05). No change in distensibility and wall thickness values occurred in control subjects.

The early reduction in arterial distensibility and increase in arterial wall thickness characterizing uncomplicated normotensive Type I diabetes patients shows a measurable worsening over the short term.