Sex differences in glucose metabolism of streptozotocin-induced diabetes inbred mice (C57BL/6J)

Considering that sex differences in glucose metabolism are observed in mice, researchers unconsciously use male mice to reduce variations by an estrogen cycle in female mice. In this study, we investigated the sex differences in glucose homeostasis in streptozotocin (STZ)-induced diabetes inbred mice (C57BL/6J). The C57BL/6J male and female mice were injected with or without STZ (40 mg/kg) for 5 consecutive days. Levels of fasting blood glucose (FBG), glycosylated hemoglobin (HbA1C), lipid profiles, oral glucose tolerance, and insulin resistance were measured at 3 and 6 weeks after STZ treatment. The FBG level in the STZ-induced male (M-STZ) group was significantly higher than that in the STZ-induced female (F-STZ) group during the entire experimental period. Furthermore, HbA1C and glucose tolerance levels in the M-STZ group were significantly higher than those in the F-STZ group at 3 and 6 weeks after STZ treatment. The glucagon/insulin ratio in the M-STZ group was significantly higher than that in the F-STZ group. Values of the homeostatic model assessment-insulin resistance, an indicator of β-cell function and insulin resistance, significantly increased in both the M-STZ and F-STZ groups at 3 weeks after STZ treatment. However, insulin resistance was observed in the M-STZ group, but not in the F-STZ group, at 6 weeks after STZ treatment. Taken together, our results indicate that glucose metabolism in the M-STZ group was worse than that in the F-STZ group, indicating that estrogen may have an important role in glucose metabolism by STZ treatment.