NPPB and atrial fibrillation: Furthermore, patients with DM had a worse NYHA class but at the same time lower levels of N-terminal pro b-type natriuretic peptide (NT-proBNP) than those without DM, which may be explained by the association of obesity with lower natriuretic peptide levels and by the lower prevalence of atrial fibrillation (AF) in diabetic patients compared with those without DM.