Circadian rhythm of blood pressure in diabetes mellitus: evidence, mechanisms and implications.

Circadian misalignment has been implicated in the development of diabetes mellitus and cardiovascular disease. Circadian rhythms of blood pressure (BP) and heart rate (HR) have long been known and the mechanisms controlling them have been actively investigated in physiology and disease. In this respect, the introduction of 24-hour ambulatory blood pressure monitoring (ABPM) has enabled a more accurate assessment of circadian BP patterns in order to solve diagnostic uncertainty or to establish dipper status. However, attention has been mainly focused on measures of extent (midline estimating statistic of rhythm, MESOR, and amplitude) rather than timing (acrophase) of changes within a cycle. The review summarises 1) evidence for altered characteristics of BP rhythm (in particular, phase shifts along the time axis) in animal and human diabetes mellitus, 2) the mechanisms that have been supposed to underlie the observed changes in cardiovascular function before diabetes onset and during progression of the disease, and 3) the adverse consequences that may result from an altered circadian BP rhythm.