Variability of betaine and homocysteine metabolites. Variablity in subjects with diabetes (n = 34) and control subjects (n = 17). DMG: N,N-dimethylglycine. The p values are the significance of the differences between the variances of the subjects with and without diabetes, calculated using log-transformed data. The change in homocysteine is the difference between the plasma homocysteine before and 4 h after a methionine load; plasma betaine and homocysteine concentrations are fasting, before a methionine load.