Angiopoietin-like protein 3 (ANGPTL3) is secreted by the liver and was recently postulated to be an important hormone regulating serum triglyceride levels. In the present study, in order to clarify the regulation of ANGPTL3 gene expression in diabetic states, we examined mRNA and protein levels of ANGPTL3 in the livers of diabetic animals. The level of ANGPTL3 mRNA was increased approximately 2.2-fold in the livers of streptozotocin (STZ) diabetic mice, and this effect was reversed by administration of insulin. Furthermore, the level of ANGPTL3 mRNA was increased more than 3.0-fold in type 2 diabetic obese mice, db/db mice, as compared with age matched lean littermates. The hepatic level of ANGPTL3 protein was also increased in these diabetic mice to an extent similar to that of ANGPTL3 mRNA. Thus, the expression of ANGPTL3 was enhanced in both insulin-deficient and -resistant diabetic states. These results strongly suggest ANGPTL3 to play an important role in hyperlipidemia in diabetes. (C) 2004 Elsevier Inc. All rights reserved.