M. B., a Negro woman, aged 40, first came under our observation in July 1934. She was ushered rather dramatically into the diabetic clinic, staggering on the arm of the attendant. She was gasping for breath and unable to talk. Her clothing was drenched with sweat; huge beads poured from her face and neck, and from her dependent fingers drops fell with regular frequency, forming a pool on the floor. She had been sitting quietly on the bench awaiting her turn to be seen when this attack occurred. Since we believed this to be an insulin reaction, she was immediately given orange juice, and in a few minutes she was herself again, except for the drenched clothing. We were amazed to learn that she had taken no insulin and to find that these attacks had recurred at intervals of approximately two hours for the past nine years, day and night.