Diabetes as a risk factor for cardiac conduction defects: A review

Diabetes mellitus (DM) is a major risk factor for cardiovascular disease and mortality with increasing prevalence in the ageing population. Coronary artery disease is the major cardiovascular abnormality in DM patients. Cardiomyopathy and left ventricular hypertrophy are two other known associated cardiovascular abnormalities. There are a few non-randomized studies reporting increased prevalence of cardiac conduction abnormalities, such as right bundle branch block (RBBB), bifascicular block and high degree atrioventricular (AV)-block but not left bundle branch block (LBBB), in DM patients. Most clinicians are not aware of this association, and it is rarely mentioned in the published reviews about cardiovascular abnormalities in this population. The cause of cardiac conduction abnormalities in DM patients is not known. If autonomic neuropathy or DM-associated cardiovascular disease plays a role, it remains unknown. The goal of this manuscript is to review the current literature about the risk of conduction abnormalities in DM patients. For this study, Medline, Google and published books were searched and reviewed for any references that matched cardiac conduction abnormalities, AV-block, BBB for bundle branch block, LBBB, RBBB, bifascicular block, autonomic neuropathy and DM.