CCL4 and type 2 diabetes mellitus: In T2D individuals, fractalkine levels did not correlate with MCP-1 levels (r = −0.17, P = 0.42) (Additional file 1: Figure S1 While, in non-diabetic subjects (Fig. 2e–h), only the CCL4 was found to correlate positively with systemic fractalkine levels (r = 0.49, P = 0.01).