Insulin resistance triggers the developments of diabetes mellitus and atherosclerosis. Tribbles homolog 3 (TRIB3) is involved in insulin resistance. We aimed to investigate whether TRIB3 is implicated in diabetic atherosclerosis. Sixty 3-week-old apolipoprotein E (ApoE-/-)/LDR receptor (LDLR-/-) mice were randomly divided into chow and diabetes groups. Diabetes was induced by a high-fat and high-sugar diet combined with low-dose streptozotocin. Mice in both groups were randomly divided into vehicle and TRIB3-silencing groups. After transfection, all mice were killed to evaluate the effects of TRIB3 on atherosclerosis. Silence of TRIB3 markedly decreased insulin resistance (P=0.039) and glucose (P=0.019), regardless of diabetes. Ultrasonography-measured parameters were similar in both groups, with and without silence of TRIB3. However, silence of TRIB3 decreased the aortic atherosclerotic burden (P=1×10(-13)). Further study showed that in brachiocephalic lesions, fibrous cap thickness, cap-to-core ratio, collagen content, and the number of smooth muscle cells were significantly increased (P<0.01 for all) by silence of TRIB3, whereas lipid and macrophage contents remained unaltered, with the vulnerability index significantly reduced. Moreover, the numbers of apoptotic cells and macrophages in brachiocephalic lesions were both significantly decreased (P<0.01 for both). Macrophage migration was decreased (P=4×10(-4)) by knocking down TRIB3, whereas adhesion and phagocytosis were increased (P<0.05 for both). Silence of TRIB3 would diminish atherosclerotic burden and increase the plaque stability in diabetic mice.