Platelet aggregation in diabetes mellitus.

Thirty-eight patients with juvenile diabetes mellitus, aged 21-77, were tested for platelet aggregation in vitro. Vascular complications were found in 20 patients with diabetic retinopathy in 16 of these. All patients received their usual dose of insulin in the morning on the day of the examinations, where were carried out shortly before a 2--3 hours after lunch. Ninety normal controls were tested at the same time of day. The aggregation was estimated turbidometrically and defined by the threshold concentration of adenosine diphosphate or adrenaline that produced a secondary aggregation with a light transmission not less than 80% of that given by the platelet-poor plasma. No significant differences could be demonstrated in platelet aggregation between the normal controls and the patients with diabetes mellitus or any subgroup of these. No correlation was found between the threshold concentrations and the plasma levels of glucose or beta-hydroxybutyric acid.