We read with great interest the article by Pereira et al1 showing an inverse association of coffee intake with risk of type 2 diabetes mellitus in a large prospective study of postmenopausal women. The protective effect of coffee against diabetes could not be attributed to caffeine because the inverse associations of coffee consumption with diabetes risk were stronger for decaffeinated coffee than for regular (caffeinated) coffee.1 The authors concluded that other components of coffee such as antioxidants could reduce the risk of diabetes, but the question remains of why regular coffee consumption might not decrease the risk of diabetes. In this setting, it would have been interesting to investigate the contribution of the homocysteine-raising effect of caffeine to the risk of diabetes.
Peyrin-Biroulet L, Guéant J, Roblin X. Coffee and Diabetes: Is Homocysteine the Missing Link?. Arch Intern Med. 2007;167(2):204. doi:10.1001/archinte.167.2.204-a