Coffee and Its Major Polyphenols in the Prevention and Management of Type 2 Diabetes: A Comprehensive Review

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by insulin resistance and impaired glucose metabolism and affects a substantial portion of the global population. Over the past few decades, numerous studies have investigated lifestyle factors, including diet and physical activity, as preventive measures or adjunctive treatments for T2DM. Among the dietary factors, coffee consumption has garnered attention because of its potential to mitigate the risk and progression of T2DM. This review examines the current evidence on the relationship between coffee consumption and T2DM, with particular focus on the major polyphenols found in coffee, such as chlorogenic acid and related hydroxycinnamic acids (caffeic acid, ferulic acid, p-coumaric acid, and sinapic acid). These bioactive compounds are thought to exert anti-diabetic effects through several mechanisms, including improvements in glucose homeostasis, insulin sensitivity, inflammation, and oxidative stress. This review aimed to clarify the scientific rationale behind the potential therapeutic effects of coffee on T2DM and proposed directions for future studies. However, significant knowledge gaps remain, including limited clinical evidence, unclear optimal dosages, low bioavailability, and an incomplete understanding of molecular mechanisms. Addressing these gaps through well-designed clinical trials and advanced molecular studies is essential to fully establish the therapeutic potential of coffee and its polyphenols in T2DM.