Diabetes mellitus disturbs kisspeptin-neurokinin B-dynorphin A (KNDy) neurons in the arcuate nucleus (ARC), which regulate pulsatile luteinizing hormone (LH) secretion in both sexes. However, it remains unclear whether a sex-specific association with the negative effects of diabetes on KNDy neurons exists. Therefore, we examined mRNA expression in KNDy neurons of diabetic male and female rats 7 weeks after streptozotocin (STZ) injection using histochemistry. In gonad-intact rats, the numbers of Kiss1 and Pdyn mRNA-expressing cells in the ARC decreased in an STZ-dose-dependent manner; moreover, no sex-dependent association with STZ treatment was observed. In males, plasma LH and sex steroid levels decreased in diabetic rats. Conversely, those of females did not vary significantly between the control and diabetic rats. Kiss1 expression in the anteroventral periventricular nucleus was slightly affected in diabetic animals, but did not exhibit sex-dependent differences. In gonadectomized rats, the numbers of KNDy mRNA-expressing cells in the ARC and plasma LH levels decreased in diabetic male and female rats; however, sex-dependent differences did not exist. These results demonstrated that a sex-specific association with the negative effects of diabetes on KNDy neurons did not exist. Therefore, the stage of diabetes that induces the suppression of the hypothalamus may not vary according to sex.