The aim of this study was to determine the effects of alternating magnetic field on the metabolism of the healthy and diabetic rats. The rats were divided into two experimental groups. Magnetic fields of 5 and 8mT intensity was applied to the first group of rats for 3 weeks (C(5mT), CMF(5mT), C(8mT) and CMF(8mT)). The second group was identified as diabetics group and 5mT was applied (D(5mT) and DMF(5mT)). The control groups (C(5mT), C(8mT), D(5mT)) of applied magnetic fields were placed in the same cage of the rats in experimental groups that have the same conditions but no pass current. The weights of rats exposed to magnetic fields in experimental groups were increased to initial weight; the plasma glucose levels were decreased in the blood parameters of the healthy and diabetic rats that they were exposed to 5mT and 8mT intensity magnetic fields. The decrease of the level of the total cholesterol and triglyceride in the blood plasma of the rats, showed that magnetic fields affected the hormonal systems, directly or indirectly, and slowed down the metabolism or hidratation.