In the course of investigating diabetic retinitis, many instances of increased capillary fragility were noted in the absence of blood dyscrasia or obvious vitamin C deficiency. For this reason it was considered important to investigate capillary fragility in diabetes, since the literature contains no record of such a study. Reported methods of determining this vascular abnormality vary so widely in technic and in interpretation that it was deemed necessary to evaluate the known methods before undertaking this investigation.
Capillary fragility is usually determined by one of two methods, either negative or positive pressure being used. The first method, introduced by Hecht,1 consists essentially in application of negative pressure over a standard area of skin for a given period of time. Most of the subsequent investigators2 have used a procedure in which a glass cup, 10 to 28 mm. in diameter at the mouth, is pressed for one minute