Taking blood pressure therapy first thing in the morning puts patients at a greater risk of developing diabetes than if they take their drugs as they settle down to sleep, researchers in Spain have shown.
In two studies published in the European Association for the Study of Diabetes’ journal Diabetologia, Ramon Hermida and colleagues at the University of Vigo show that lowering blood pressure (BP) while a patient sleeps represents a target for intervention to prevent new cases of diabetes, and that taking an entire daily dose of hypertension medications at bedtime reduces a patient’s risk of developing diabetes compared with taking medications after waking.
In their first study
, Hermida’s team tested two novel hypotheses: firstly, whether sleep-time BP is a prognostic marker for future development of diabetes; and, secondly, whether progressive reduction of sleep-time BP actually reduces the risk of developing diabetes.
“The main findings indicate that sleep-time BP is indeed a highly significant prognostic marker for new-onset diabetes,” says Hermida, “while clinic BP measurements are not.”
In their second study
, Hermida’s team looked at whether taking an entire daily dose of one or more blood pressure medications at bedtime is more effective at reducing the risk of developing diabetes than taking all medications upon waking.
The results from this randomised clinical trial indicate a 57% decrease in the risk of developing diabetes with the bedtime regimen compared with the post-waking regimen.
The hypotheses tested in their studies seemed logical to Hermida’s team, supported by current literature and their previous work on ambulatory blood pressure monitoring (ABPM) in patients with and without diabetes.
“However,” says Hermida, “when you test a novel hypothesis, you are open to the unexpected. The results are so clear and significant that they are a bit of a surprise.”
Richard Elliot, research communications manager at Diabetes UK, says the results are worth noting, but unsurprising.
“We already know that high blood pressure is linked to a greater risk of developing type 2 diabetes and that changing the time of day when you take blood pressure medications can affect their impact,” says Elliot.
“These new studies add to our understanding by suggesting that night time blood pressures are more closely linked to type 2 diabetes risk than daytime blood pressures, and that taking medications before bedtime to lower night-time blood pressures might help to reduce that risk.”
Elliot says studies involving larger numbers of people are needed to confirm these findings. “People should not alter their blood pressure medications without speaking to their doctor,” he says.
Hermida agrees that wider studies are needed. His group is coordinating an ongoing project in Spain called Hygia, involving 40 clinical sites in Galicia, Northwest Spain, and 292 investigators. The project has recruited over 18,000 patients who undergo periodic evaluation by ambulatory BP monitoring, says Hermida.
Ambulatory BP monitoring is “a cost-effective technique that should be recommended in all adults, as recently proposed by the US Preventive Services Task Force,” says Hermida.
There is no clinical reason to take BP medications in the morning, says Hermida. “There is no study showing advantages of morning treatment when compared to bedtime therapy in terms of survival, just the very opposite,” he concludes.
 Hermida R, Ayala D, MojÃ³n A et al, Sleep-time BP: prognostic marker of type 2 diabetes and therapeutic target for prevention. Diabetologia 2015. doi:10.1007/s00125-015-3748-8
 Hermida R, Ayala D, MojÃ³n A et al, Bedtime ingestion of hypertension medications reduces the risk of new-onset type 2 diabetes: a randomised controlled trial. Diabetologia 2015. doi:10.1007/s00125-015-3749-7