Purpose Glucose metabolism underpins diabetic cataracts (DCs), but the relationship between the two remains unclear. Here, we tested the aqueous humour (AH) of patients with DCs to elucidate glucose metabolite levels. Methods In this study, aqueous humour (AH) samples were collected preoperatively from DC eyes (n = 37) and age-related cataract eyes (n = 37) from 74 patients (74 eyes) undergoing uncomplicated cataract surgery. The content of glucose, pyruvate, L-lactate were detected by biochemical methods and advanced glycation end-products (AGEs) was detemined using enzyme-linked immunosorbent assay (ELISA) technique. Furthermore, the ratios of glucose/pyruvate and L-lactate/pyruvate in the AH were calculated. In addition, we calculated the correlation between glucose levels and AGEs in the AH. Results The concentrations of glucose, pyruvate and AGEs in the DC group were higher than those in the control group. Significantly lower levels of L-lactate in the AH were found in the DC group. We calculated the glucose/pyruvate ratio and the L-lactate/pyruvate ratio in the AH, which showed that glucose metabolism was changed in the AH from DC patients. Interestingly, we observed that AGEs in the AH were significantly correlated with increased anterior chamber glucose permeability. A stronger correlation was found in the subgroups of male patients, younger patients, and patients with poor glycaemic control status. Conclusions Comparison of the levels of glucose metabolism-related products in the AH in the DC group highlight a potential pathological mechanism for DC from a glucose metabolism perspective. The findings indicated an alteration in the metabolic pathways of energy metabolism and amino acids in the AH of DC patients.