Lack of Blood Pressure Decreases at Night Signal Adverse Outcomes Risk in Diabetes

Martina Chiriacò, MD

A new study is providing insight into the potential for adverse outcomes associated with a lack of change or increases in blood pressure at night among adult patients with diabetes.

Presented at the American Heart Association’s Hypertension Scientific Sessions 2021, results of the study, which included up to 21 years of follow-up data from patients, suggest non-dipping and reverse dipping blood pressure patterns were associated with increased prevalence of cardiac autonomic neuropathy and decreased survival probability.

“Previous studies have shown that non-dipping is linked to kidney and cardiovascular disease in healthy individuals and in people with hypertension, or type 1 or type 2 diabetes,” said study investigator Martina Chiriacò, MD, an investigator in the department of clinical and experimental medicine at the University of Pisa in Italy, in a statement from the American Heart Association. “However, the long-term effects of non-dipping on death among people with diabetes remains unclear, and information on reverse dippers is extremely scarce. We sought to investigate these two aspects to highlight whether altered patterns of blood pressure might predict mortality risk in people with type 1 or type 2 diabetes.”

Chiriacò and colleagues from the University of Pisa designed the current study with an interest in describing the differences in outcomes observed with altered blood pressure and patterns and heart rate variability in diabetes over a longer follow-up period than has been included in previous studies. With this in mind, investigators designed their study to assess these potential associations in a cohort of 349 patients with either type 1 or type 2 diabetes and available 24-hour ambulatory blood pressure and heart rate variability monitoring recruited in Pisa, Italy in 1999 and followed for 21 years.

Exposures of interest for the study were dipping, non-dipping, and reverse dipping status. For the purpose of analysis, dipping, non-dipping, and reverse dipping were defined as a 10% or greater decline, less than 10% decline, and an increase of 0.1% or more in average night-time systolic blood pressure (SBP) compared to average daytime SBP, respectively.

Of the 349 patients identified for inclusion in the analyses, 166 were considered dippers, 144 were considered non-dippers, and 39 were considered reverse dippers. The median follow-up for the study cohort was 21 (14-21) years, providing a total of 6251 person-years of follow-up data for analysis. Additionally, the cohort was 52% women, the mean age was 57.1±11.9 years, a mean BMI of 29.4±5.9 kg/m2, and a mean HbA1c of 8.6±2.1%. During the follow-up period, 136 deaths occurred.

Compared to dippers, non-dippers and reverse dippers appeared to have progressively higher prevalence of cardiac autonomic neuropathy (11%, 16%, and 31%, respectively), low heart rate variability (45%, 53%, and 62%, respectively), and 24-hour hypertension (40%, 60%, and 67%, respectively). Additionally, results suggested dippers had lower rates of isolated nocturnal hypertension (5%, 27% and 49%, respectively) and postural hypotension (14%, 26%, and 43%, respectively) compared to non-dippers and reverse dippers.

Further analysis suggested reverse dippers and non-dippers had progressively lower mean overall survival compared to dippers with mean overall survival times of 16.1±5.3 years, 17.5±5.3 years and 18.6±4.6 years, respectively. Investigators noted reverse dippers appeared to be at more than twice the risk of all-cause mortality (HR, 2.3 [95% CI, 1.4-3.8]) compared to dippers after adjustment for age, sex, BMI, office SBP, plasma glucose, and diabetes duration and type. Investigators also pointed out patients with low heart rate variability appeared to have reduced mean overall survival (16.9±5.5 and 18.8±4.4 years, respectively), but a similar adjusted risk (HR, 1.3 [95% CI, 0.9-1.9]) when compared to those with a high heart rate variability. No significant interactions were observed between blood pressure patterns, heart rate variability, and diabetes type on overall survival.

“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,” Chiriacò said. “It is important that health care professionals look for abnormal blood pressure dipping patterns in people with type 1 or type 2 diabetes. There are strategies to reduce blood pressure during the night.”

This study, “Prognostic Value Of 24-hour Ambulatory Blood Pressure and Heart Rate Patterns in Diabetes: A 20-year Longitudinal Analysis of The Chronic Diabetes Complications and All-cause Mortality in Pisa from 1999 Onwards (CHAMP1ON) Study Cohort,” was presented at the American Heart Association’s Hypertension Scientific Sessions 2021.