Moreover, successful periodontal therapy reduces HbA1c levels in type 2 diabetes mellitus (T2DM) by an average of 0.4 %, demonstrating that the relationship between periodontitis and diabetes is causal in nature.66 The increased serum/plasma concentrations of the adipokine apelin in diabetes and obesity46 are therefore also of interest. The gene discussed is APLN; the disease is type 2 diabetes mellitus.