Diabetic retinitis is still an enigma not only to the ophthalmologist but to the internist as well. Too frequently is the internist confronted with a diabetic patient who has been referred by his conscientious "eye man" because of a retinitic state which, in fact, neither one can to any great extent influence. For the internist has come to realize that seldom does the most meticulous diabetic control of which he is capable cause any semblance of a reversal of the pathologic process in the eye or even a staying of the process. It would be well, therefore, if the two fields of medical endeavor would establish some mutual understanding as to their respective therapeutic limitations so that what little common knowledge is at hand might be used to the greatest advantage of the patient. What constitutes adequate diabetic control for the unfortunate patient, and what is the rationale of the