Pulse pressure and systolic night-day ratio interact in prediction of macrovascular disease in patients with type 2 diabetes mellitus.

Patients with type 2 diabetes mellitus are at increased risk of cardiovascular disease (CVD). We examined the predictive ability of 24-hour ambulatory pulse pressure (24-h PP), ambulatory arterial stiffness index (AASI) and diurnal blood pressure (BP) parameters for fatal and non-fatal CVD in patients with type 2 diabetes mellitus. A total of 108 patients with type 2 diabetes mellitus (mean duration 6.6 years) were followed for 9.5 (0.5-14.5) years. At baseline, all patients underwent ambulatory BP monitoring. During follow-up, 45 patients had cardiovascular (CV) events (35 non-fatal and 10 fatal). In bivariate analysis, events during follow-up were predicted by 24-h PP (P<0.01), AASI, 24-h systolic BP and systolic and diastolic night-day BP ratio (P<0.05 for all). In Cox regression analysis adjusted for established risk markers, only 24-h PP and systolic night-day BP ratio predicted CV events, P<0.05 for both. A significant interaction between the two parameters was found, P<0.05; thus, the higher the systolic night-day ratio, the greater the increase in hazard ratio (HR) per mmHg increase in 24-h PP and vice versa. A combined 10 mmHg increase in 24-h PP and 10%-point increase in systolic night-day ratio from the 25th percentile increased the adjusted HR (95% confidence interval) for CV events with 1.29 (0.53; 3.12), whereas a similar increase from the 75th percentile increased the HR with 4.2 (1.54; 11,51). Our study showed that 24-h PP and systolic night-day ratio interact as predictors of CV events in type 2 diabetes patients, and should be considered in conjunction when evaluating the risk of CVD.