Non-dipping of nocturnal blood pressure linked to adverse outcomes in type 1 diabetes
medwireNews: People with type 1 diabetes who do not experience a nocturnal reduction in blood pressure (BP) may have an elevated risk for mortality and adverse kidney events, research suggests.
Speaking at the virtual 57th EASD Annual Meeting, Henrik Hjortkjaer (Steno Diabetes Center Copenhagen, Denmark) explained that BP usually dips by more than 10% during the night, and previous studies have shown that non-dipping is associated with an increased risk for cardiovascular disease (CV) in people with type 2 diabetes and those without diabetes.
However, “we do not know the prevalence and consequences of non-dipping in type 1 diabetes,” he said.
To address this gap, the team measured 24-hour ambulatory BP using a tonometric wrist-watch device in 654 people with type 1 diabetes between 2009 and 2011, and assessed the incidence of subsequent adverse outcomes using national registries and electronic medical records, with follow-up in 2017. Participants were aged an average of 55 years and had a median diabetes duration of 35 years.
Hjortkjaer reported that the average daytime systolic BP was 133 mmHg, dropping to an average of 121 mmHg overnight, giving an average dip of 9.2%. Non-dipping – defined as a nocturnal decrease of less than 10% – occurred in over half of the participants (51.5%) during the 24-hour monitoring period.
In a model adjusting for age, sex, diabetes duration, BMI, and glycated hemoglobin, non-dipping was associated with a significantly increased risk for mortality (hazard ratio [HR]=2.33), and this association remained significant after further adjustment for factors including smoking, prior CV disease, and medication use (HR=2.12).
People in the non-dipping group were also significantly more likely than those with nocturnal dipping to experience the composite kidney outcome of decline in estimated glomerular filtration rate (eGFR) of at least 30%, end-stage kidney disease, and mortality, at HRs of 2.63 and 1.92 after partial and full adjustment, respectively.
When the renal outcomes were analyzed separately, non-dipping was significantly associated with having an eGFR decline of at least 30% (HR=1.78) and end-stage kidney disease (HR=5.96) in the partially adjusted analysis, but these associations lost statistical significance after full adjustment. There was no significant association between non-dipping and the risk for CV events.
Taken together, these findings raise the question of whether bedtime dosing of antihypertensive medications could reduce the risk for mortality and adverse kidney outcomes in people with type 1 diabetes and nocturnal non-dipping, said Hjortkjaer.
He noted that previous study results have demonstrated a significant increase in rates of dipping among people with type 1 diabetes given bedtime versus morning dosing of enalapril, but “we do not have data on hard endpoints.”
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