Chronic elevation of growth hormone (GH) induces resistance to insulin and hyperinsulinemia in both humans and animals, whereas calorie restriction (CR) improves peripheral insulin sensitivity in many species. To investigate the mechanisms which lead to insulin resistance in animals with high levels of GH, as well as the mechanisms which might improve insulin sensitivity, we fed GH-overexpressing transgenic (Tg) mice ad libitum (AL) or subjected them to 30% CR. We then assayed the plasma adipocytokines levels related to insulin sensitivity, plasma lipid levels and tissue triglycerides accumulation, and examined adipocytes morphology. Furthermore, we evaluated mRNA expression and protein levels of enzymes or regulators involved in regulating hepatic lipid metabolism. Our results suggest that decreased plasma adiponectin, increased plasma resistin and cholesterol, and elevated levels of TNF- and IL-6 in adipocytes may all contribute to the insulin resistance observed in GH-Tg mice. Increased accumulation of triglycerides and impaired adipocytes differentiation in GH-Tg mice provide plausible mechanisms for the alterations of adipocytokines. Hepatic and muscle insulin resistance in these mice is probably related to excessive accumulation of fatty acids and their metabolites. An increase in plasma adiponectin and decrease in plasma IL-6, triglycerides and cholesterol levels in response to CR may improve insulin sensitivity.