The exposure to extremely low-frequency electromagnetic fields (EMFs) could adversely affect the endocrine system and cellular proliferative response. Nonetheless, the use of 60-Hz EMFs in the form of magneto-therapy exerts beneficial actions on human health but can also induce hyperglycaemia. Therefore, the present study was aimed to search for metabolic responses of fed or fasted male rats to a single EMF exposure. We performed a 15 min-single exposure to 60-Hz (3.8 mT, intensity) EMF, and determined serum levels of glucose, lipids, and indicators of cellular redox state and energy parameters. A single exposure to a 60-Hz EMF induced hyperglycaemia in both animal groups, and an attenuated second serum insulin peak. The 60-Hz EMF also decreased free fatty acids and lactate serum levels, oppositely increasing pyruvate and acetoacetate levels. Significant increases in blood glucose level and rat’s glucose metabolism were related to a more oxidized cellular redox state and variations in insulin and glucagon secretion. The 60-Hz EMF’s effects were not modified in animals previously subjected to chronic EMFs exposure (14 days). In conclusion, increased serum glucose levels and glucose metabolism induced by a single 60-Hz EMF exposure were closely related to the cellular redox state and the insulin/glucagon ratio.