Aims: To establish reference data for ambulatory blood pressure (AMBP) in normotensive, normoalbuminuric Type 1 diabetic patients and characterize the relation to clinic blood pressure (BP). To evaluate the statement of the third working party of the British Hypertension Society (BHS) that a target clinic BP in diabetes < 140/80 corresponds to a target day-time AMBP < 130/75 mmHg.
Patients and methods: AMBP were performed in 172 normoalbuminuric, adult Type 1 diabetic patients, who had never received anti-hypertensive drugs. Clinic BP was determined as the mean of at least three auscultatory (Hawskley random zero manometer) and as the mean of at least three oscillometric (Spacelabs) BP values obtained just prior to ambulatory monitoring. Five patients with more than three missing hours/24 h were excluded.
Results: For 30 patients auscultatory clinic BP exceeded 140 mmHg systolic and/or 90 mmHg diastolic. For the remaining 137 normotensive patients day-time AMBP was 125.7/77.2 mmHg and oscillometric clinic BP was 125.3/76.5 mmHg (mean difference 0.3/0.7 mmHg; 95% confidence interval (CI) -0.9 to 1.5/-0.3 to 1.7 mmHg, P = 0.6/P = 0.2). Sixty-five percent of the patients had a diastolic day-time AMBP > 75 mmHg.
Conclusions: Clinic BP and day-time AMBP measured by the same method were indistinguishable. The target for day-time diastolic AMBP (< 75 mmHg) proposed by the BHS is too low and is based on the misconception that in normotensive subjects day-time AMBP is lower than clinic BP. If the BHS guidelines are strictly adhered to, the consequence may be overtreatment in patients with normoalbuminuria and no end organ damage.