Many, but not all, of the symptoms of diabetes can be controlled by the administration of insulin. The forms of insulin available early in the 20th cent. had to be injected frequently because they were quick-acting. Later modifications gave the insulin solution a more prolonged action so that hypodermic injections could be made less frequently. Some now control their insulin levels via a small, portable insulin pump. In certain cases of mild diabetes, oral medications that stimulate production of insulin can be taken in lieu of insulin. See glucagon.