In contrast to our results, in a large Caucasian population COMT Val108/158Met was associated with T2DM [29], while DBH-1021C/T was significantly associated with T2DM and other clinical phenotypes responsive to peripheral sympathetic tone in a tissue-specific manner [37], implying that present study lacked the statistical power or the needed sample size to detect these associations. This evidence concerns the gene DBH and type 2 diabetes mellitus.