Glucose Tolerance Factor (GTF) is synthesized in vivo from absorbed dietary chromium, and acts as a physiological enhancer of insulin activity, binding to insulin and potentiating its action about three-fold. Since GTF is well absorbed orally, the development of sufficiently concentrated and stable supplementary sources of this agent may enable convenient and physiologically appropriate pharmacological modulation of insulin activity. A review of the numerous physiological actions of insulin suggests a number of therapeutic applications for GTF, in such diverse ailments as diabetes mellitus, hyperlipidemia, reactive hypoglycemia, obesity, cancer, protein malnutrition or malabsorption, endogenous depression, Parkinsonism, hypertension and cardiac arrhythmias. GTF supplementation may also have value in preventive medicine.