Coefficient of variation of R-R intervals during deep breathing as a risk marker of orthostatic blood pressure decline in patients with Type 2 diabetes mellitus

Diabetic orthostatic hypotension, associated with cardiovascular autonomic neuropathy, can be assessed using the coefficient of variation of the R-R interval (CVRR). We investigated whether CVRR during deep breathing could serve as a risk indicator for orthostatic blood pressure decline in patients with type 2 diabetes. This study included 88 hospitalized patients aged 51.5–71.4 years with type 2 diabetes undergoing diabetes education or glycemic control. Blood pressure changes during postural transitions were measured using a non-invasive beat-to-beat blood pressure monitoring device. Participants were divided into two groups based on CVRR values measured at rest and during deep breathing, using a cutoff of 2%. Blood pressure changes during postural transitions were compared. At rest, no significant differences in systolic or diastolic blood pressure changes were observed between the autonomic dysfunction group (CVRR ≤ 2%, n = 42) and the non-autonomic dysfunction group (CVRR >2%, n = 46; p > 0.05). However, during deep breathing, patients with CVRR ≤ 2% (n = 20) exhibited significantly greater decreases in systolic blood pressure at 0–30, 31–60, 61–90, 91–120, and 151–180 seconds after standing (p < 0.05). These findings suggest that a CVRR below 2% during deep breathing serves as a risk indicator for orthostatic systolic blood pressure decline in patients with type 2 diabetes.