Background: Minor blood pressure (BP) alterations detected by ambulatory BP monitoring (ABPM) was associated with microvascular disease in type 2 diabetes mellitus (DM). We examined whether a previously described afternoon BP peak is linked to hypertension status and associated with microvascular complications.
Methods: A cross-sectional study was conducted with 207 type 2 DM patients (56 years, 52.7% men). ABPM was determined by oscillometry.
Results: An increase in both systolic and diastolic BP occurred in the afternoon; the same pattern was observed across hypertension categories (normotensive, prehypertensive, or hypertensive). We calculated BP increase for the period between 2 and 8 PM as the difference between mean BP at 8 PM and mean BP at 2 PM (calculated by the average of four measurements in each hour). The cohort was then divided into two groups (afternoon BP increase below or above the group's median). The prevalence of diabetic retinopathy (DR) was higher in those with afternoon increment above the group median for both systolic (50 vs. 30%, P = 0.004) and diastolic (47 vs. 33%, P = 0.04) BP. For systolic BP, this result was maintained after adjustments for age, gender, A1c test, DM duration, total cholesterol, and 24-h systolic BP. Afternoon BP increments for both systolic and diastolic BP correlated significantly with urinary albumin excretion rate (UAER) after adjusting for 24-h BP (systolic: r = 0.17, P = 0.01; diastolic: r = 0.16, P = 0.02). However, when adjusted for all covariates, these correlations were no longer significant.
Conclusions: An increment in afternoon BP was observed in type 2 diabetic patients regardless of hypertension status; that increment was associated with higher prevalence of DR but not diabetic nephropathy independently of measured confounders.