Trigonelline is a pyridine derivative known to contribute indirectly to the formation of desirable flavor products, including furans, pyrazine, alkyl-pyridines, and pyrroles, during coffee roasting. The amount of trigonelline in arabica is higher than that in robusta green coffee beans, and thus it can be used as a marker compound to distinguish the coffee bean species. During the roasting process of coffee beans, trigonelline changes into N-methylpyridinium and nicotinic acid as its major products, which makes it a useful index of the degree of roasting. The importance of trigonelline in coffee is connected to nutritional aspects. It has been revealed in recent studies that the administration of trigonelline allows diabetic rats to avoid diabetes-related organ damage and live longer, which can make it a potentially strong candidate for industrial application as a pharmacological agent for the treatment of hyperglycemia, hyperlipidemia, and liver/kidney dysfunctions. In addition, the urinary concentrations of trigonelline and its thermal product N-methylpyridinium of coffee drinkers are higher than those of noncoffee drinkers, which indicates that trigonelline and N-methylpyridinium may have potential as dietary biomarkers that could be used as analytical probes to control compliance in human intervention studies on coffee. Trigonelline has been isolated from many plants: fenugreek seeds (Trigonella foenum-graecum, hence the name), garden peas, hemp seed, oats, potatoes, Stachys species, dahlia, Strophanthus species, and Dichapetalum cymosum. In a randomized cross-over trial, the critical effect of Trigonelline on glucose tolerance has been studied during a 2-hour oral glucose tolerance test (OGTT) in 15 overweight men. Results showed that glucose and insulin concentrations significantly reduced 15minutes after Trigonelline consumption compared with placebo.