Despite the eminent importance of studies with primary and cultured adipocytes or adipose tissues on the basis of their physiological role in the regulation of lipid and carbohydrate metabolism in humans in combination with the relative low expenditure in preparing adipocytes of high quality and number, compounds and drug candidates for future antidiabetic and antiobesity therapy have to be analyzed for their effects in primary and cultured hepatocytes and myocytes or liver and muscle tissues, too. In principle, the majority of the assays described above for adipocytes can be adapted for the use with hepatocytes and myocytes. However, the following selection takes into account the relative contribution of each process monitored to its role in the whole-body regulation of intermediary metabolism in the normal and disease state. Moreover, technical aspects, such as requirement for a special equipment and applicability in throughput screening assays for drug discovery, were additional criteria.