INS and diabetes mellitus: Then, logistic regression models, using all and matched subjects, were fitted and further confirmed that tryptophan was positively associated with diabetes risk and independent of both physical and metabolic markers including age, gender, BMI, fasting and 2 h postprandial glucose, fasting and 2 h postprandial insulin, and HOMA-IR (p trend < 0.001 for both; odds ratio of all participants = 2.54 (95%CI: 1.85, 3.48); odds ratio of matched subjects = 5.06 (95%CI: 2.31, 11.10)).