Controlling diseases. A well-known example of this is the use of insulin injections by people with diabetes mellitus. The injected insulin is needed because secretion of the body's own insulin, by the pancreas, is not adequate to control blood sugar levels. Another example of a control treatment is the use of medication to prevent fits (seizures) in animals and people with epilepsy. Knowing what causes diseases like diabetes and epilepsy is necessary before treatments that control them can be devised.