The research by the group from Spain is the latest effort to link sleep patterns, or disruption of sleep, to the development of type 2 diabetes.
A pair of papers published Thursday say taking blood pressure medication at night can is more effective and can cut the risk of developing type 2 diabetes (T2D) by half. The studies, which come from the same research team at the University of Vigo in Spain, appear in Diabetologia, the official journal of the European Association for the Study of Diabetes. Ramon C. Hermida, PhD, led the research.
The first paper shows that sleep-time blood pressure is likely the best target for intervention in preventing new cases of T2D. A dip in blood pressure during sleep is normal, but in patients at risk for developing T2D, this does not occur. Thus, in the second paper, the researchers examined whether having patients take all their blood pressure drugs at night instead of the morning would help keep T2D from developing.
The importance of blood pressure at night. The first paper involved 2656 patients without diabetes (1292 men and 1364 women), with a mean age or 50.6 years. Patients’ blood pressure was monitored for 48-hour periods at least once a year—or more frequently if medication was adjusted—to accurately gauge blood pressure during the day and at night.
During a 5.9-year median follow-up, 190 people in the study developed T2D. The most important predictor of whether a patient developed the disease was the systolic blood pressure while the patient was sleeping. The researchers controlled for other factors, such as waist circumference and chronic kidney disease, but blood pressure during sleep came out on top.
Treatment at night versus morning. This study involved a randomized, open-label, blinded endpoint trial with 2012 patients who had high blood pressure but not T2D. The study included 976 men and 1036 women, with a mean age of 53 years. Patients were randomized to take all their blood pressure medications at night or upon awakening in the morning. A separate group of investigators who did not know when patients were taking their medication assessed the onset of newly developed diabetes.
During a median follow-up of 6 years, 171 participants developed T2D. The difference between the 2 groups was significant: 12.1% of the 1029 subjects who were assigned to take medication in the morning developed T2D, compared with 4.8% of the 983 assigned to take their therapy at night.
The difference in nighttime blood pressure may account for what happened over time: the “non-dipping” effect in blood pressure occurred in 32% of the bedtime-treated patients, compared with 52% of the morning-treated patients. Thus, the bedtime treated patients had a 57% decrease in the risk of developing T2D, after adjusting for factors such as waist circumference and mean asleep systolic blood pressure.
The risk of developing T2D dropped even more for those taking bedtime medication compared with those taking morning regimens of angiotensin receptor blockers (61%), ACE inhibitors (69%), and beta blockers (65%). The authors say that these medications reduce or block the effects of angiotensin 2, a hormone that raises blood pressure and causes increased glucose release from the liver.
Thursday’s papers are among a recent string of studies that link sleep patterns—or disruption of sleep—with development of diabetes and problems with high blood pressure. Work by Frank Hu, MD, PhD, of Harvard School of Public Health, previously reported in Evidence-Based Diabetes Management, has discussed links between shift work and increased risks of diabetes, obesity, depression, and higher health costs.
Hermida RC, Ayala DE, Mojon A, Fernandez JR. Sleep-time BP: prognostic marker of type 2 diabetes and therapeutic target for prevention [published online September 23, 2015}. Diabetologia. 2015; http://link.springer.com/article/10.1007%2Fs00125-015-3748-8.
Hermida RC, Ayala DE, Mojon A, Fernandez JR. Bedtime ingestion of hypertension medications reduces the risk of new-onset type 2 diabetes: a randomized controlled trial [published online September 23, 2015]. Diabetologia. 2015; http://link.springer.com/article/10.1007/s00125-015-3749-7.