Retinal fluorescein angiography and hemoglobin A1C in borderline diabetes.

In a controlled study fluorescein angiography of the retina and measurements of hemoglobin A1C were carried out in subjects with slightly abnormal two-hour glucose tolerance and controls with normal glucose tolerance. Fluorescent dots were present in 50 per cent of the series with a reduced glucose tolerance. Leakage from retinal vessels was noted in 20 per cent. In the control group fluorescent dots were present in 25 per cent, of whom none showed leakage. In neither of the series did any subject display ophthalmoscopically visible signs of diabetic retinopathy. In the subjects with abnormal glucose tolerance the mean concentration of hemoglobin A1C was 5.88% +/- 1.15 (SD) and in the control group 5.11% +/- 0.85 (SD) (P less than 0.05) . No correlation was demonstrable between the number of fluorescent dots, hemoglobin A1C and age in the group with abnormal glucose tolerance, but a relationship was noticed between a hereditary disposition to diabetes mellitus and presence of fluorescent dots. Smoking appeared not to have any influence. The result of the present study indicates that incipient retinal microvascular changes and evidence of an early breakdown of the blood-retinal barrier may be present in subjects before diabetes becomes manifest.