Cyclosporine A (CsA)-based therapy has been implicated in the development of diabetes. Hence, its effects on hepatic carbohydrate metabolism and gene expression will be investigated.Sprague-Dawley rats given 15 mg/kg body weight/day of CsA for 20 days, as well as healthy untreated animals, received a glucose load enriched with [U-(13)C]glucose and deuterated water to resolve load and endogenous contributions to plasma glucose. Blood glucose and plasma insulin levels were assayed and at 60-min post-load, plasma glucose (13)C and (2)H-enrichments were analyzed by nuclear magnetic resonance spectroscopy and liver tissue analyzed for hepatic gene expression.CsA-treated rats were glucose intolerant relative to controls (AUC(glucose) = 21,297 ± 857 versus 14,183 ± 1094, p < 0.01). Contributions from endogenous glucose production (EGP) were significantly elevated in CsA-treated rats (179 ± 16 versus 123 ± 13 mg/dl, p < 0.05). The increased endogenous contributions were attributable to glycogenolysis or glucose-G6P cycling and not to gluconeogenesis. Significantly higher expressions of fatty acid synthase and acetyl-CoA carboxylase 1 and 2 genes were observed in CsA-treated rats.CsA-altered glucose metabolism and gene expression could reflect increased hepatic insulin resistance. In the liver of CsA-treated animals, EGP suppression is impaired whereas hepatic de novo lipogenesis is enhanced contributing to dysregulated glucose and lipid metabolism.