Diabetes mellitus (diabetes) is a prevalent, costly condition that causes significant illness, disability, and premature death. An estimated 15.7 million people (5.9% of the total U.S. population) have diabetes, 1 of whom 5.4 million are undiagnosed. In 1997 alone, 789,000 new cases were diagnosed. 1 Moreover, according to 1996 death certificates, diabetes is the seventh leading cause of death in the United States. 1 The costs of diabetes to the American healthcare system are enormous, with total (direct and indirect) costs estimated at $98 billion in 1997. 2 Our systematic reviews focused on population-based strategies to improve the care of people with either type 1 or type 2 diabetes. (Type 1 diabetes results from destruction of the b-cells of the pancreas, and type 2 is charac-188 *Insufficient evidence means that we were not able to determine whether or not the intervention works.