Reduced number of angiotensin II receptors on platelets in insulin-dependent diabetes.

Angiotensin II receptors on platelets were studied in 13 patients with uncomplicated type I diabetes mellitus and in 15 age-matched normal subjects. Receptor density on cells from the diabetic patients was 15% lower than the normal subjects (5.2 +/- 0.8 SD sites/platelet in diabetic patients and 6.4 +/- 0.8 in normals, P less than 0.001), but there were no differences in receptor affinity as measured by Kd (4.9 +/- 1.5 X 10(-10) mol/l in diabetic patients and 5.4 +/- 1.4 X 10(-10) mol/l in normals). Plasma concentrations of renin and angiotensin II were similar in both groups. The reduced density of angiotensin II receptors on platelets from patients with insulin-dependent diabetes may reflect a generalized abnormality of angiotensin II receptor regulation.