The observed greater frequency and relatively earlier occurrence of senile cataract in patients with diabetes mellitus have led to numerous investigations of the carbohydrate metabolism in patients with cataract. Thus, Baldwin and Bartel, in 1924, in a study of one hundred and thirty-two cases of cataract, reported ninety-nine with a blood sugar during fasting above 120 mg. per hundred cubic centimeters of blood. In a study of a hundred cases of senile cataract in 1925, H. Maxwell Langdon found a blood sugar during fasting above the normal limits in fifteen cases, while forty-five of the patients had a lowered dextrose tolerance. In 1928, O'Brien found a blood sugar concentration during fasting above 120 mg. in 84 per cent of seventy-four patients with cataract and a lowered tolerance in 45 per cent. In a further study, in 1931, O'Brien found hyperglycemia in about 50 per cent of a series of