Ninomiya T, et al. - In a Japanese community, researchers studied if there was a connection between serum ethylamine levels (as an indicator of l-theanine consumption) and the development of type 2 diabetes. A total of 2,253 community-dwelling Japanese people between the ages of 40 and 79 without diabetes were monitored for 7 years. Two hundred eighty-two developed type 2 diabetes during follow-up. In a general Japanese population, higher serum ethylamine was significantly linked to a lower risk of the development of type 2 diabetes. For objective estimation of the consumption of l-theanine, calculating the concentration of serum ethylamine would be a useful biomarker.