A new study says taking hypertension medication at bedtime significantly improved sleep time blood pressure while also reducing the risk of diabetes.

Two studies conducted by researchers from the University of Vigo in Spain have explored the impact of sleep-time blood pressure on new-onset diabetes risk. The findings are published in the journal Diabetologia.

In the first study, Dr. Ramón Hermida and colleagues set out to investigate the value of using blood pressure to predict new-onset diabetes, prospectively examining 2,656 individuals of varying blood pressure levels who did not have diabetes at the beginning of the study.

After an average of 5.9 years of follow-up, 190 participants had developed type 2 diabetes. The researchers found that sleep-time blood pressure levels were a significant marker for the development of diabetes, with alterations in blood pressure preceding rather than following the onset of the disease. This first study suggested to the researchers that lowering sleep-time blood pressure could be a novel method for reducing the risk of new-onset diabetes.

In the second study, Dr. Hermida and colleagues aimed to test whether taking hypertension medication before sleeping was more effective at reducing the risk of diabetes than taking medication after waking up. For this study, 2,012 people with high blood pressure were randomly assigned to either take all of their hypertension medication upon awakening or to take the entire daily dose of one or more of their prescribed medication at bedtime.

None of the participants had diabetes at the start of the study, and the researchers tracked the developed of the disease for a median of 6 years. During the follow-up period, 171 participants developed type 2 diabetes. Those who were assigned to take their medication before bedtime had significantly lower average sleep-time blood pressure and a greater sleep-time relative blood pressure decline than those who took their medication in the morning.

Prevalence of "non-dipping" - whereby blood pressure during sleep-time falls by less than 10% compared with daytime blood pressure - was lower in those who took their medication at bedtime. Non-dipping occurred in 32% of this group compared with 52% of those who took their medication in the morning.

Most importantly, however, was the finding that the risk of new-onset type 2 diabetes decreased by 57% in the group of patients who took their medicine before bedtime.

The greatest reductions in risk came with taking medications that target a hormone called angiotensin II. This hormone is responsible for increased blood pressure, increased glucose release from the liver and decreased insulin sensitivity.

"In hypertensive patients without diabetes, ingestion of the entire daily dose of one or more blood pressure-lowering medications at bedtime compared with ingestion of all such medications upon awakening results in significantly improved sleeping blood pressure control and prevention of new-onset diabetes," the researchers conclude.

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