To evaluate the quality of diabetes care, processes and outcomes of health care for type 2 diabetes were compared across three population-based surveys in Germany with cross-sectional and longitudinal perspectives. The surveys were conducted in the Augsburg region, southern Germany, in 1999-2001, 2003-2005, and 2006-2008 and included physical examinations, an interview, self-administered diabetes questionnaires, and laboratory tests. Quality indicators derived from guidelines for type 2 diabetes managed care programs in Germany served as the evaluation framework. Multiple regression models were used for analysis, adjusting for age, sex, education, diabetes duration, and cardiovascular comorbidity. Results show that medical examinations of eyes (61-71%) and feet (38-55%) and the use of antihypertensives, antiplatelet drugs, and lipid-lowering medications were reported more frequently over time. There was no increase in patient self-care behaviors or diabetes education. Blood pressure and cholesterol outcome targets were achieved more frequently over time. In conclusion, medical care and drug therapy of type 2 diabetes have improved; however clinical practice has failed to intensify patient participation and health behavior.