According to a report from the World Health Organization, diabetes, which affects approximately 422 million people worldwide, is expected to double in prevalence over the next 20 years. The use of insulin is a common method for treating diabetes. Hyperglycemia is controlled through the administration of insulin or oral antidiabetic medications, with 90% of patients having type 2 diabetes. Diabetes mellitus is broadly divided into two categories: Type 1, which results from immunological disorders and beta-cell deficiency in the pancreas leading to insulin secretion issues, and Type 2, related to insulin secretion defects and resistance. In some patients, insulin receptors may be insensitive, while in others, there may be issues with insulin signaling, or an unidentified cause may exist.

Carbon quantum dots (CQDs) are a class of carbon-based nanomaterials that have gained attention for their small size, low toxicity, good biocompatibility, and tunable hydrophilicity for various applications, including biomedical and drug delivery. In addition, these carbon quantum dots exhibit fluorescent properties, making them useful for tracking substances they are attached to, such as drugs, thus facilitating drug monitoring. When a carbon atom forms four bonds with different atoms, it can be a chiral atom. Chirality plays a significant role in physiological activities, with the ability of a substance to rotate polarized light referred to as optical activity. Enantiomers are spatial isomers that have non-superimposable mirror images. The D and L enantiomers rotate polarized light to the right and left, respectively. By selecting chiral precursors (such as D and L amino acids) in the synthesis of carbon quantum dots, chirality can be imparted to them. As a result, CQDs can appear as D and L enantiomers based on their synthesis source. It has been shown that D and L enantiomers of a substance can have opposing effects, with L and D enantiomers exerting different therapeutic effects, such that one enantiomer may have a desirable therapeutic effect while the other not only lacks this effect but may also cause side effects. Given these points, investigating the effects of D and L enantiomers of carbon quantum dots on the efficacy of insulin in diabetes could be intriguing.