https://pubmed.ncbi.nlm.nih.gov/19374234/
Conclusions: (1) EPR spectroscopy can be used to determine the in vitro level of L-ascorbic acid radical in human lenses. (2) The in vitro L-ascorbic acid radical level in cataract lenses of patients with diabetes was lower than in patients without diabetes. (3). Lower in vitro level of L-ascorbic acid radical in lenses of patients with diabetes means lower in vivo level of vitamin C, what suggests an increased intensity of free radical reactions in the group of patients with diabetes than in the group without diabetes.