High BP at night linked to double risk of death in diabetics

New York, Oct 1:  Adults with Type 1 or Type 2 diabetes whose blood pressure increased at night had more than double the risk of dying compared to those whose blood pressure "dipped" during sleep, according to a 21-year study presented recently at the American Heart Association's Hypertension Scientific Sessions 2021.

Blood pressure normally declines, or dips, during sleep. If blood pressure does not adequately decrease during the night, it is called "non-dipping." If blood pressure increases at night relative to daytime levels, the phenomenon is referred to as "reverse dipping." These abnormal blood pressure patterns are associated with increased risks of cardiovascular complications and death in adults with Type 1 or Type 2 diabetes.

"Our study shows that 1 in 10 people with type 1 or type 2 diabetes could be a reverse dipper, and that this condition likely more than doubles the risk of death from any cause over 21 years' time, regardless of blood pressure control. It is important that healthcare professionals look for abnormal blood pressure dipping patterns in people with Type 1 or Type 2 diabetes," Martina Chiriaco, an investigator in the department of clinical and experimental medicine at the University of Pisa in Pisa, Italy.

In the study, the researchers also assessed the role of heart rate variability in their study group. Heart rate variability is a measure of the variation in times between each heartbeat.

"Low heart rate variability is associated with worse health for people with heart failure and increases the risk of coronary artery disease in the general population. However, there is still a scarcity of long-term information on the association of reduced heart rate variability with mortality among people with Type 1 or Type 2 diabetes," Chiriaco said.

Researchers studied 349 adults with diabetes in Pisa, Italy, beginning in 1999. Researchers found more than half of the participants had non-dipping blood pressure during the night, and 20 per cent were reverse dippers.

They also found that nearly one-third of reverse dippers had cardiac autonomic neuropathy versus 11 per cent of those who had no dips. Cardiac autonomic neuropathy is a serious complication of diabetes in which the nerves that control the heart and blood vessels are damaged. This nerve damage affects blood pressure and heart rate regulation, increasing the risk of death and cardiovascular events.

Compared to dippers, reverse dippers had an average of 2.5 years reduced survival, and non-dippers had an average of 1.1 years reduced survival.