News & Research

Influence of time of day of blood pressure–lowering treatment on cardiovascular risk in hypertensive patients with type 2 diabetes, by Ramón C. Hermida and colleagues. Diabetes Care 34:1270–1276, 2011

What is the problem and what is known about it so far?

Blood pressure rises and falls naturally depending on the time of day. Normally blood pressure is lower at night during sleep and starts to rise upon waking. It rises until the afternoon, when it is at its highest point, and begins to fall as the evening comes. Having blood pressure that does not behave this way can be a sign of a health problem. People with diabetes often have high blood pressure at night and are already at increased risk for heart and blood vessel disease. Having high blood pressure puts a strain on the heart, damages blood vessels, and increases the risk of heart attack, stroke, and kidney disease. Studies have shown that medicine used to lower blood pressure can affect blood pressure levels during the night depending on whether it was taken in the morning or the evening.

Why did the researchers do this particular study?

The researchers wanted to find out whether taking blood pressure drugs in the evening instead of the morning would help control blood pressure during sleep in individuals with type 2 diabetes. Keeping blood pressure controlled overnight lowers the risk of heart and blood vessel disease.

Who was studied?

A total of 448 adults with type 2 diabetes and high blood pressure who were already on blood pressure–lowering medicine were studied.

How was the study done?

The participants were randomly chosen to either take all their blood pressure medicine in the morning or at least one medicine at night. At least once a year for about 5 years, each participant wore a device on the wrist that measured blood pressure every 20 minutes during the day and every 30 minutes during the night for 48 hours. Participants visited the clinic to have blood pressure measurements taken by the researchers each week the device was worn. Because activity changes blood pressure, the device also measured activity throughout the day and night. This allowed the researchers to better measure blood pressure by taking into account the physical activity of the day.

What did the researchers find?

The patients who took at least one medication at night had lower overnight blood pressure. Their risk of heart and blood vessel disease was also lower.

What were the limitations of the study?

This study did not look into whether increasing the number of medications taken in the morning could have a similar effect to taking at least one at night. No medication can provide steady control for the whole 24-hour period. This means that medications taken in the morning will be less effective by bedtime. If more medication is taken in the morning, their combined strength could keep blood pressure low into the night.

What are the implications of the study?

Diabetic patients with high blood pressure are at greater risk of heart and blood vessel disease. High blood pressure overnight is one of the main concerns. Taking one or more blood pressure medications in the evening reduces the risk of heart and blood vessel disease.

For More Information

High Blood Pressure

Heart Disease

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