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People with diabetes showed worse long-term survival if they had irregular nighttime blood pressure (BP) patterns, according to a cohort study from Italy.

Reverse dipping, defined as a ≥0.1% increase in average nighttime systolic BP compared with average daytime systolic BP on 24-hour ambulatory BP monitoring (ABPM), was observed in 11% of the 349-person CHAMP1ON cohort, the majority of whom were dippers exhibiting normal ≥10% dips in BP at night, reported Martina Chiriacò, MD, of the University of Pisa.

Reverse dippers had an average overall survival of 16.1 years, compared with 18.6 years for dippers over a median 21.0 years of follow-up. The difference persisted after adjustment for BP control and other factors (adjusted hazard ratio [aHR] 2.2 for all-cause mortality, 95% CI 1.3-3.8), Chiriacò told the audience during this year's hosted by the American Heart Association (AHA).

In addition, patients with low 24-hour heart rate variability trended toward shorter overall survival without the difference reaching statistical significance (16.9 vs 18.8 years with high variability; aHR 1.2, 95% CI 0.8-1.8).

Chiriacò concluded that "24-hour ABPM is an ideal tool for the diagnosis of abnormal BP and [heart rate] circadian variations and can help tailor the treatment of patients with uncontrolled nocturnal BP; for example, administering antihypertensive medications in the evening rather than in the morning."

Taking antihypertensives at night is thought by some to confer better BP control during sleep and is a strategy backed by randomized data from the Hygia Chronotherapy Trial. Other work has also shown nighttime dosing to reduce incident diabetes among people with hypertension.

However, nighttime hypertensives are controversial.

Hygia's validity is with concerns about the implausibility of the findings and the trial's conduct, pointing to between-group differences at baseline suggestive of a faulty randomization process. European Heart Journal, where the Hygia manuscript had been published, has not retracted the paper and has instead opted to that the trial is under investigation.

The ongoing and studies are expected to provide definitive answers regarding bedtime dosing of BP-lowering medications.

In Chiriacò's report, mortality risk was nearly doubled for reverse dippers compared with non-dippers, the roughly 40% of study participants with <10% declines in nighttime systolic BP. Non-dippers survived a mean 17.5 years over follow-up and had the same risk of mortality as dippers.

Previous studies have associated non-dipping nighttime BP with kidney and cardiovascular disease in healthy individuals and in people with hypertension, or type 1 or type 2 diabetes. Similarly, low heart rate variability has been linked to worse outcomes for heart failure patients and greater risk of coronary artery disease in the general population, Chiriacò noted in an .

The CHAMP1ON cohort included 349 patients recruited in Pisa who had type 2 diabetes (n=284) or type 1 diabetes (n=65) and had undergone in-office BP measurement and 24-hour ABPM at baseline.

Study participants were an average 57.1 years old and were roughly split between the sexes. Prevalence of hypertension was 82%, and that of uncontrolled hypertension despite BP-lowering drugs was 73%.

Reverse dippers were more likely to be older and to have hypertension. This group also had a higher prevalence of cardiac autonomic neuropathy, chronic kidney disease, and concentric cardiac remodeling.

Chiriacò acknowledged that the study comprised a predominantly white population. "This is particularly important since non-dipping has been reported to be more common among people with African or Hispanic ancestry," she said.

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