OBJECTIVE To examine endothelial function (EF) noninvasively in IDDM and NIDDM patients with long diabetes duration.

RESEARCH DESIGN AND METHODS We studied EF in 17 IDDM patients without diabetic complications and in 25 NIDDM patients with comparable glycemic control and with diabetic complications and compared both with nondiabetic control subjects matched for age, sex, and lumen diameter. Using high-resolution ultrasound, we measured the endothelialdependent (FAD%) and independent vasodilation (GTN%); the blood flow at rest, postocclusive, and after application of 400 μg glyceroltrinitrate of the brachial artery; and the intima media thickness (IMT) of the common carotid artery.

RESULTS In the IDDM patients, neither FAD% (8.2 ± 4.6 vs. 7.6 ± 4.2%), GTN% (16.3 ± 4.9 vs. 18.4 ± 6.4%), nor postocclusive blood flow (40.6 ± 19.1 vs. 39.3 ± 23.6 cm/s) differed from the control subjects. IMT (0.59 ± 0.10 vs. 0.55 ± 0.14 mm) was slightly, but not significantly, elevated. In contrast, the NIDDM patients showed an impaired FAD% (3.8 ± 3.3 vs. 6.9 ± 4.4%, P < 0.01), no difference in GTN%, and a decreased postocclusive blood flow (18.5 ± 13.8 vs. 32.7 ± 20.0 cm/s, P < 0.01). IMT was significantly increased in NIDDM patients (0.77 ± 0.14 vs. 0.62 ± 0.10 mm, P < 0.001).

CONCLUSIONS In contrast to NIDDM patients with cardiovascular complications, IDDM patients with long diabetes duration and good long-term metabolic control do not have impaired EF compared with control subjects.