方法：SD大鼠随机分为正常对照组(NC)、正常波动组(NF)、糖尿病模型组(DM)和糖尿病波动组(DF)。腹腔注射STZ诱导糖尿病，NF和DF两组大鼠每天三次腹腔注射葡萄糖造成血糖波动，第8wk取视网膜，采用单细胞凝胶电泳(SCGE)技术检测DNA损伤程度。

结果：NF和DF两组大鼠血糖变化明显而且规律，波动曲线稳定，评价血糖稳定性的各项指标较NC组均有明显的增高，DF组升高更显著，差异有统计学意义(P<0.01)。SCGE显示NF，DM和DF三组细胞均有不同程度的DNA损伤，彗星尾长(TL)、尾部DNA含量(TDNA%)、尾矩(TM)和Olive尾矩(OTM)四指标均高于NC组，多组及两组间比较差异均有统计学意义(P<0.01)。

结论：糖尿病大鼠视网膜组织存在DNA损伤，血糖波动可加重损伤，表明高血糖和血糖波动可能参与了视网膜组织DNA损伤的机制，可能是DR发生的早期事件之一，在DR的发生发展中起了重要的作用。

METHODS: SD rats were randomly divided into four groups: normal control group(NC), normal fluctuation group(NF), diabetes group(DM)and diabetes fluctuation group(DF). Diabetic models were established through intraperitoneal injection of STZ. A certain amount of glucose was injected in the rats of group NF and DF in an intraperitoneal mode three times a day after the model was established, thereby causing blood glucose fluctuations. Rats were killed and the retinal tissues were taken in the 8th week. Single cell gel electrophoresis(SCGE)technique was adopted for detecting DNA injury extent in the retina tissue.

RESULTS:Groups NF and DF showed significant and regular fluctuations. The curve of blood glucose fluctuations was relatively stable. All values of MBG, SDBG, LAGE and M were significantly increased compared with group NC. Group DF was increased more significantly. It was statistically significant(P<0.01). SCGE showed that there were DNA damages in different levels in the cells of group NF, DM and DF. Indicators of cells such as TL, TDNA%, TM, OTM were higher than that in group NC. It was statistically significant(P<0.01). The comparison difference between two groups was also significant(P<0.01).

CONCLUSION: Rat retinal tissues have DNA injury during early diabetic period. DNA injury is gradually aggravated with blood glucose fluctuation. It indicates that high blood glucose and blood glucose fluctuation are involved in the mechanism of cell DNA injury, and they may be one of DR early event, have played a certain role in the incidence of DR.