## 1 Introduction  
Diabetes mellitus has become an increasing challenge in global public health. The main cause of diabetes mellitus is defective insulin secretion, leading to insulin resistance (IR) in tissues and organs and impaired pancreatic \(\beta\)-cell function, which induces disorders of glucolipid metabolism and subsequent development of a pathological state characterized by hyperglycemia and dyslipidemia [1, 2]. Among the subtypes of diabetes mellitus, type 2 diabetes mellitus (T2 DM) dominates, with epidemiologic data showing accounts for up to 90% of cases in the total prevalent population [3]. Studies have shown that conventional diabetes medication can control the disease but has side effects associated with long-termuse, such as bloating and diarrhea. Therefore, dietary interventions with safety, economy, and effectiveness are more appropriate for the long-term management of diabetes [4; 5]. Meanwhile, studies have disclosed the intimate association between the pathogenesis of T2 DM and gut microbiota [6; 7]. When the gut microbiota is in a state of homeostatic imbalance, its metabolites and abnormal immunoregulatory function may become the causative factors of metabolic syndrome-like diseases, such as obesity, T2 DM, and dyslipidemia [8; 9]. Based on this, it is essential to explore dietary interventions that can synchronously regulate the abnormalities of glucolipid metabolism and optimize the function of the gut microbiota. Mulberry leaf is a medicinal and food catalog ingredient with high medicinal and culinary value [10]. Research has found that mulberry leaves are full of vitamins, minerals, protein and other nutrients and flavonoids, alkaloids, phenols, polysaccharides, and other functional components, with hypoglycemic, hypolipidemic, inhibition of drug toxicity, antioxidant, and other functional effects [11; 12]. Mulberry leaves harvested after the frost are usually used for medicinal purposes [13]. In numerous ancient Chinese medical books, mulberry leaves were mostly collected after being exposed to frost, and mulberry leaves included in the previous editions of the Chinese Pharmacopoeia were also frost mulberry leaves, which indicates that frost-covered mulberry leaves have higher medicinal value [14]. It has been demonstrated that there are seasonal variations in the amount of functional components found in mulberry leaves, with the amount of flavonoid components dramatically increasing following frost [13; 15]. [PERSON] et al. hypothesized that low temperature induces gene expression of enzymes critical in the pathway of flavonoid synthesis and promotes an increase in flavonoid content [14]. Therefore, frosted mulberry leaves have the potential as a functional food ingredient. Currently, most mulberry leaves are still used as silkworm feed or discarded, resulting in a waste of resources. Consequently, it is imperative to investigate the logical utilization of functional components found in mulberry leaves. Mulberry leaf extract pharmacological studies for the treatment of diabetes mellitus are the primary focus of the current antidiabetic research on mulberry leaves [16]. In T2 DM mice, [PERSON] et al. and [PERSON] et al. confirmed that mulberry leaf aqueous extracts had a hypoglycemic impact [17; 18]. [PERSON] et al. isolated the flavonoid components of mulberry leaves and examined their mode of action and hypoglycemia potential [19]. It should be noted that the majority of research has been conducted using conventional methods, including alcohol and water extraction, to extract the useful components. These extraction methods will cause some waste of functional components in mulberry leaves and will also increase the production cost [20]. Consequently, the primary goal of this research is to fully utilize bioactive substances in frosted mulberry leaves and fill the research gap of frosted mulberry leaves as a functional food ingredient in practical applications.