Acute, ambulatory and central blood pressure measurements in diabetes

Sammanfattning: Background: In patients with diabetes, high blood pressure is an established risk factor for cardiovascular disease. The aim of this thesis was to explore the associations between blood pressure levels measured with different techniques and during different circumstances, and the degree of cardiovascular organ damage and subsequent prognosis in patients with diabetes.Methods: We analysed baseline data from patients with type 2 diabetes who participated in the observational cohort study CARDIPP (Cardiovascular Risk factors in Patients with Diabetes – a Prospective study in Primary care), and longitudinal data from patients registered in the Swedish national quality registry RIKS-HIA (Register of Information and Knowledge about Swedish Heart Intensive care Admissions). Patients in CARDIPP underwent nurse-recorded, 24-hour ambulatory and non-invasive central blood pressure measurements. Patients in RIKS-HIA had their systolic blood pressure measured upon hospitalisation for acute chest pain.Results: In CARDIPP, nearly one in three patients with office normotension (<130/80 mmHg) were hypertensive during the night (≥120/70 mmHg). This phenomenon, masked nocturnal hypertension, was significantly associated with increased arterial stiffness and increased central blood pressure. Furthermore, nearly one in five CARDIPP patients with office normotension had high central pulse pressure (≥50 mmHg), and there was a significant association between high central pulse pressure and increased carotid intima-media thickness and increased arterial stiffness. Among CARDIPP patients who used at least one antihypertensive drug, those who used beta blockers had significantly higher central pulse pressure than those who used other antihypertensive drugs, but there were no significant between-group differences concerning office or ambulatory pulse pressures. In CARDIPP patients with or without antihypertensive treatment, ambulatory systolic blood pressure levels were significantly associated with left ventricular mass, independently of central systolic blood pressure levels. When RIKS-HIA patients, admitted to hospital for chest pain, were stratified in quartiles according to admission systolic blood pressure levels, the risk for all-cause one-year mortality was significantly lower in patients with admission systolic blood pressure in the highest quartile (≥163 mmHg) than in patients with admission systolic blood pressure in the reference quartile (128-144 mmHg). This finding remained unaltered when the analysis was restricted to include only patients with previously known diabetes.Conclusions: In patients with type 2 diabetes, ambulatory or central blood pressure measurements identified patients with residual risk factors despite excellent office blood pressure control or despite ongoing antihypertensive treatment. Ambulatory systolic blood pressure predicted left ventricular mass independently of central systolic blood pressure. In patients with previously known diabetes who were hospitalised for acute chest pain, there was an inverse relationship between systolic blood pressure measured at admission and the risk for one-year all-cause mortality.