The substitution of sulfonylurea drugs in the treatment of diabetes demands even more careful observation of the patient than may be required with the use of insulin. It is especially important to recognize that patients tend to regard a disorder, even diabetes, as minor when oral medication is employed, and omission of the drug may be looked upon as relatively unimportant. With the use of the sulfonylurea drugs the dynamic qualities of the diabetes should be appreciated, also an intimate knowledge of the pharmacology. It is emphasized that the sulfonylurea drugs have a maximum of effectiveness. Accordingly, a higher dosage beyond a given limit does not increase their value. Thoughtful cooperation of the patient as to diet and medication is essential.