Type II non-insulin-dependent diabetes mellitus (NIDDM) occurs predominantly in adults, especially in those individuals over age 30. This disease was formerly called maturity-onset or adult-onset diabetes. A subclass of NIDDM was devised, however, for those families in which children, adolescents, or young adults develop what is referred to as maturity-onset diabetes of the young. This article reviews issues related to treatment modalities for those with type II NIDDM, including dietary management, physical activity, and pharmacologic therapy.