OBJECTIVES: To construct a novel and clinically relevant means of representing self-monitored blood pressure (SMBP). METHODS: Patients treated to an office blood pressure (BP) < 130/80 mmHg measured their BP at home for 14 days using an Omron IC semi-automatic portable monitor with memory. SMBP data were transferred from the monitor to a computer to produce graphic profiles (SMBPp) that depict the hourly variation in BP throughout a "typical" or modal day. RESULTS: Office BP and SMBP data from 66 subjects with type 2 diabetes and hypertension (HTN), who completed a previous study of intensified management, were analyzed based on European Society of Hypertension-European Society of Cardiology (ESH-ESC) classifications. Patients were classified as Optimal (6), Normal (12), High Normal (15), Isolated systolic HTN (29) and Grades 1, 2 or 3 HTN (4). SMBP disagreed in 32 cases, placing 29 patients in higher risk categories. Analysis by SMBPp of the 33 patients originally classified as Optimal, Normal or High Normal showed that on average 50 +/- 31% of their systolic SMBP values exceeded ESH-ESC thresholds for HTN (135 mmHg). It also revealed that 74 +/- 21% of their SMBP values exceeded the treatment goal (< 25 mmHg) for high-risk patients with type 2 diabetes. CONCLUSIONS: SMBPp allowed for a definitive measurement of the dynamic daily BP changes. It produced compelling evidence of persistent patterns of BP fluctuations among patients with normal office BP whose uncontrolled HTN would have remained undetected.