A 65-year-old man diagnosed with essential hypertension had been treated with antihypertensive medication for 2 years at his physician’s office. His systolic/diastolic blood pressure in the office had been controlled at about 130/80 mm Hg with 2 antihypertensive drugs taken in the morning after breakfast. Although he does not have any cardiovascular complications, he is a smoker, is obese, and has diabetes.

Because this patient’s characteristics (relatively older age, male sex, relatively higher office blood pressure, use of 2 or more antihypertensive drugs, diabetes, obesity, and smoking habit) have been reported to be associated with the risk of so-called “masked” (uncontrolled) hypertension (MHT), the patient received 24-hour ambulatory blood pressure monitoring.

The average value of the patient’s 24-hour ambulatory blood pressure was 142/86 mm Hg. The circadian profile showed the highest blood pressure in the early morning and a relatively lower blood pressure in the late morning, when the effects of the antihypertensive medications were maximal. His blood pressure increased gradually in the afternoon and showed the second peak in the evening. The average blood pressure in the daytime (awake) was 146/88 mm Hg. Although his blood pressure decreased at night, his average blood pressure in the nighttime (sleep) was 124/78 mm Hg, which is still higher with regard to the recommended upper limit of nighttime blood pressure. Thus, the diagnosis of MHT was made.

Based on the current evidence, the patient was told that individuals with MHT are more likely to develop cardiovascular events, especially if they have diabetes and other risk factors. The patient was also told to take the same antihypertensive drugs in the evening after dinner as well as in the morning after breakfast. After 2 months of treatment, repeated ambulatory blood pressure monitoring showed good blood pressure control throughout the 24 hours.