AIM: To evaluate the effect of epigallocatechin gallate (EGCG) in preventing lens opacity and the aggregation of lens αB-crystallin in model rats of diabetes mellitus (DM). METHODS: This experimental study included Wistar rats for DM as in vivo models and divided into 5 groups. The treatment groups were administered EGCG by orally for 20d and were then assessed for their degree of lens opacity with binocular microscope and lens αB-crystallin expression from Western blot analyze. RESULTS: Pearson correlation test and regression analysis on EGCG exposure and final random blood sugar (RBS) obtained a significance level of P<0.05. EGCG exposure can significantly lower RBS with an R2 of 0.5634 (56.34%). The same analysis on EGCG exposure and the degree of lens opacity obtained a significance level of P<0.05 and increased exposure to EGCG can significantly lower the degree of lens opacity with an R2 of 0.8577 (85.77%). Correlation analysis between EGCG and the expression of lens αB-crystallin can be concluded that the higher the EGCG exposure administered, the higher the native lens αB-crystallin expression and the lower the aggregate lens αB-crystallin expression. There was also significant effect in which every 1 mg/kg body weight dose of EGCG can increase the native lens αB-crystallin expression by 0.0063 and decrease the aggregate lens αB-crystallin expression by 0.0076. CONCLUSION: The administration of EGCG at a dose of 300, 600, and 1200 mg shows a significant effect on preventing lens opacity and aggregation of αB-crystallin in diabetic rat models and this research could be a biomolecular prevention of cataract.