Progression of carotid atherosclerosis and the role of endothelin in diabetic patients

An increased thickness of the carotid artery wall is thought to be a sign o f early atherosclerosis. Since vascular endothelium is the site of formatio n of several substances, we have investigated the rate of progression of ca rotid atherosclerosis and the contribution of endothelin (ET-1), lipid pero xides [measured as thiobarbituric acid reacting species (TBARS)] and 6-keto -Prostaglandin-F-1A (6-keto-PG-F-1A) at baseline and after 30-months. Fifty patients with Type 2 diabetes without evidence of macroangiopathy, hyperte nsion, proteinuria or proliferative retinopathy, and 27 healthy, non-diabet ic persons were studied. Arterial wall thickness was measured as the mean o f the maximum intimal-medial thickness (IMT) in 16 carotid segments by b-mo de ultrasound. The IMT values was significantly increased in diabetic subje cts (at baseline: 1110 +/- 310 mum, after 30 months: 1260 +/- 280 mum, p < 0.01), but not in control subjects (1100 +/- 280 mum, 1200 +/- 290 mum, res pectively). At baseline time both groups had similar levels of ET-1, TBARS and 6-keto-PG-F-1A. In 30-months follow-up, the ET-1 level 8.0 pmol/l (5.8 - 10.7) was significantly elevated in diabetic subjects, compared with the level at baseline time 7.43 pmol/l (4.8 - 11.1) p < 0.01. No significant di fferences were found in the other examined parameters in the studied groups . Although insulin levels remained unchanged in the two studied groups, in 30 months follow-up, the insulin level in the diabetic subjects, 92.4 +/- 3 5.1 pmol/l was significantly elevated compared with those of control subjec ts 76.0 +/- 31.0 pmol/l, p < 0.05, In conclusion, endothelis. is the main a ssociate of the change of IMT value over 30 months in diabetic patients, in whom the extent of atherosclerosis was significantly greater than in contr ol subjects.