In this study, prevalence and incidence of complications as well as co-morbidity in type 2 diabetes patients in Germany were evaluated as part of a cost-of-illness study (CODE-2(TM), Costs of Diabetes in Europe - Type 2)In a pre-study, 197 general practitioners and diabetes specialists all over Germany provided data on the complication status of 2701 randomly selected patients with type 2 diabetes. The patients were grouped into five mutually exclusive strata. This pre-study was performed to generate a general overview on complication status to select proper patients for the main study. The main study was performed on stratified samples derived from the pre-study. Irrespective of the real prevalence of the five strata, an equal number of 160 were randomly selected from each stratum. Thus, rare complications were also covered in the study. Data from 809 patients were collected retrospectively on the basis of medical files during interviews with the physician. To achieve representative estimates of absolute prevalence and incidence of diabetes-related complications in Germany, results were weighted using frequencies of the strata. Severe complications were diagnosed in 50% of these patients. Prevalences were: 10.56% myocardial infarction, 6.66% stroke, 3.97% foot ulcer, 2.30% amputations and 1.34% blindness. Overall incidences in the diabetes population were estimated at 0.78% myocardial infarction, 1.28% stroke and 0.80% amputations. 23% of the diabetes patients suffered from 2 or more complications. The complication status became considerably worse with increasing time since the diagnosis of diabetes. The mean HbA1c level was 7.51% (i.e. 122% of the upper limit of the respective normal ranges). The presence of complications and co-morbidity in type 2 diabetes patients was a frequent finding. This underlines the importance of complications in diabetes patients and the necessity to increase any means of prevention in order to relieve the personal and economic burden of type 2 diabetes.