Ambulatory blood pressure thresholds for diagnosing hypertension in type 2 diabetes based on cardiovascular outcomes

Currently proposed ambulatory (ABPM) blood pressure (BP) thresholds for diagnosis of hypertension do not differentiate, as international guidelines do for clinic BP, uncomplicated persons from those at higher risk, e.g., patients with diabetes (DM). We aimed to derive diagnostic thresholds for the awake and asleep BP means in terms of cardiovascular disease (CVD) outcome for patients with as well as without DM. We studied 3344 subjects (1718 men/1626 women), 52.6 ± 14.5 years of age, 607 with type 2 DM, during a median follow-up of 5.6 years. Those with hypertension at baseline were randomized to ingest all prescribed BP-lowering medications upon awakening or >=1 of them at bedtime. BP was measured for 48 h at baseline, and again annually in all subjects, or more frequently (quarterly) after adjustments in treatment. Physical activity was simultaneously monitored every min by wrist actigraphy. Cox regression analysis was used to derive outcome-based reference thresholds for ABPM in subjects with and without DM. CVD risk was consistently greater in patients with than without DM for awake systolic/diastolic (SBP/DBP) BP means >=130/75 mmHg and asleep SBP/DBP means >=110/65 mmHg. Using the baseline ABPM values of event- and non-event patients without DM, we calculated the sensitivity and specificity in the diagnosis of outcome-based hypertension according to the awake and asleep SBP and DBP means. The maximum combined sensitivity and specificity corresponded to threshold cutoff values of 132.7/83.2 mmHg for the awake and 119.2/69.3 mmHg for the asleep SBP/DBP means, i.e., 135/85 mmHg for the awake and 120/70 mmHg for the asleep SBP/DBP means after rounding those point estimates to the closest integer value ending in 0 or 5. The equivalent, in terms of CVD risk, cutoff values for patients with DM were 120/75 mmHg for the awake and 105/60 mmHg for the asleep SBP/DBP means, respectively. This study is the first to assess the influence of DM on the diagnostic threshold values for the awake and asleep BP means based on CVD outcomes. The proposed ABPM reference thresholds are 15/10 mmHg lower for ambulatory SBP/DBP in patients with than without DM. This marked difference indicates the need for revision of current guidelines that propose diagnostic thresholds for ABPM without differentiating between presence/absence of DM.