Days of Measuring and Times of Readings Needed for Home Blood Pressure Monitoring in the Assessment of Blood Pressure in Hypertensive Patients with Diabetes Mellitus

Background Home blood pressure(HBP) monitoring might play a role in the management of hypertension.However,the optimal schedule of measuring remains unclear.Objective We investigated how many consecutive days and how many readings on each occasion would be appropriate for the assessment of blood pressure at home in hypertensive patients with diabetes mellitus.Methods HBP monitoring was performed in uncontrolled hypertensive patients with diabetes mellitus recruited from 5 community health centres in Shanghai.HBP was measured at home for 6 consecutive days,with 5 readings each in the morning and in the evening.The Omron HEM-7051 blood pressure monitor was used at home as well as in the outpatient clinic.Results One hundred and nine subjects completed HBP monitoring according to the protocol.Of 109 subjects,39(35.8%) were men.The average age(SD) was(60.4±5.8)years old.The morning systolic/diastolic blood pressures measured at home on each of the 6 days were lower than the blood pressures measured in the clinic on the day before HBP monitoring(P0.01).The correlation coefficients were calculated for the morning and evening blood pressure readings separately,and for the mean of total 30 blood pressure readings in the 6 consecutive days with that of 15,10,and 5 readings during the first 3 and 2 days and the first day,respectively.The correlation coefficients were greater for 3 days than for 2 days(morning,0.97/0.98 vs 0.95/0.96,P=0.06/0.01;evening 0.98/0.97 vs 0.95/0.95,P0.01/0.06),and for the first single day(morning,0.97/0.98 vs 0.85/0.89,P0.01 for both;0.98/0.97 vs 0.83/0.87,P0.01 for both).We then pooled blood pressure readings measured in the morning and evening in the whole 6-day period,and calculated the correlation coefficients for the mean of 5 reading on each occasion with that of the first 3 and 2 readings and the first reading.The correlation coefficients were greater for 3 than for 2 readings(0.99/0.99 vs 0.98/0.97,P0.01 for both),and for the first single reading(0.99/0.99 vs 0.93/0.92,P0.01 for both).Conclusion In uncontrolled hypertensive patients with type 2 diabetes mellitus,HBP monitoring requires at least 3 days of measuring,with 3 readings each in the morning and evening,for reliable assessment of blood pressure.