Growth hormone (GH) is important in diabetes in view of its anti-insulin actions and its relation to the long-term complications of the disease. The suppression of GH secretion in diabetics has theoretical and possible therapeutic interest. Native somatostatin has multiple actions, including inhibition of the secretion of insulin, glucagon, thyroid-stimulating hormone (TSH), and various gut hormones. It also has inhibitory effects on gastrointestinal motility, exocrine secretion, nutrient absorption, and splanchnic blood flow. Its therapeutic use is limited by a duration of effect of several minutes only. SMS 201-995 holds more potential than native somatostatin in view of its longer duration of action. Preliminary data suggest that 50 micrograms SMS 201-995 subcutaneously at night inhibits the nocturnal rise in GH secretion in normal man, but no effect on 24-h GH secretion is observed when SMS 201-995 is injected twice daily before meals. SMS 201-995 inhibits secretion of insulin, glucagon, and TSH in addition to growth hormone and induces carbohydrate intolerance when administered before food in normal subjects. Gastrointestinal side effects suggest additional effects on nutrient disposal, which are important when it is administered before food. Further studies are required to elucidate these effects of SMS 201-995 on endocrine and gastro-intestinal function in normal and diabetic man.