Microcirculatory disorders are often a complication of diabetes. They are associated with an increased capillary permeability which can be assessed by the Landis test using 99mTc-labelled albumin. Labelled albumin retention is measured by external detection (residual radioactivity after removal of venous tourniquet). The Fast Fourier Transform of the radioactivity disappearance graph reflects the lymphatic albumin resorption. Thirteen out-patients with diabetes from 1 to 19 years suffering from evident microcirculatory disorders were treated with a micronized flavonoid fraction: Daflon 500 mg (2 tablets per day) during a month. Antihypertensive and/or antidiabetic treatment were continued during the study if they were given before starting. A test was performed before, and at the end of the treatment. In 10 of the 13 patients, the test was carried out a third time 5.5 +/- 1.0 months later, after treatment withdrawal. Results were as follows: 1) labelled albumin retention was abnormal (greater than or equal to 8%) at the start and became normal in the patients and improved in 1 patient. After treatment withdrawal, the results of the third test were again abnormal, in the patients who had been normalized beforehand; 2) the initially abnormal lymphatic resorption became normal in six of the 13 patients at the end of the treatment and became abnormal again in all patients after treatment withdrawal. In a parallel group of 15 patients with abnormal test lymphatic fluctuations and not being treated with a vasculo-protector agent, the initially abnormal test remained abnormal 5 to 48 months later in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)