Multivariate test found that DRD2/ANKK1 and ACE, but not PGC1A, allele polymorphism significantly determined the fluctuation of glycemic status in patients with diabetes (Pillai’s traces = 0.06 (0.04), 0.11 (0.07), and 0.01 (0.01); Fs(2) = 3.15 (2.04), 5.82 (3.64), and 0.67 (0.49); P = 0.047 (0.135), 0.004 (0.030), and 0.514 (0.617), respectively). Here, DRD2 is linked to diabetes mellitus.