Poster Presentation Australian Diabetes Society and the Australian Diabetes Educators Association Annual Scientific Meeting 2017

POSTER DISCUSSION: Short-term Blood Pressure Variability and Nocturnal Dipping in Diabetic Patients with and without Chronic Kidney Disease (#301)

Renata Libianto 1 2 , Christopher O'Callaghan 3 , Scott T Baker 2 , Sara Baqar 2 , Thuy Vu 2 , George Jerums 2 , Richard J MacIsaac 1 4 , Elif I Ekinci 1 2 5
  1. The University of Melbourne, Parkville, VIC, Australia
  2. Department of Endocrinology, Austin Health, Melbourne
  3. Department of Clinical Pharmacology, Austin Health, Melbourne
  4. Department of Endocrinology, St Vincent's Hospital, Melbourne
  5. Menzies School of Public Health, Darwin

Background:

Increased blood pressure variability (BPV) and lack of nocturnal blood pressure dipping (NBPD) are independently associated with excess mortality in patients with diabetes. While patients with diabetes and chronic kidney disease (CKD) have higher BP, BP fluctuations in this group are not well characterised. We hypothesised that patients with diabetes and CKD have higher BPV and are more likely to demonstrate a lack of NBPD, than their counterparts without CKD.

 

Methods:

Clinical and biochemical data were collected from 124 patients attending diabetes clinics at Austin Health.  Stage 3 to 5 CKD was defined by a CKD-EPI eGFR of <60ml/min/1.73m2. Patients underwent 24h ambulatory blood pressure monitoring within one year either side of the eGFR measurement. BPV was calculated using standard deviation (SD) and coefficient of variation (SD/mean*100). Night-to-day systolic BP ratio of >90% suggested abnormal NBPD.

 

Results:

Thirty-four patients (27%) had CKD, and they were more likely to be female, have prior macrovascular complications, and be taking antihypertensives. The mean±SD 24h systolic BP was higher in patients with CKD than those without (135±16mmHg and 129±13mmHg respectively, p=0.03), and there was a negative correlation between eGFR and 24h systolic BP.  No association was found between eGFR and BPV. A negative correlation was found between eGFR and night-to-day systolic BP ratio, whereby lower eGFR was associated with higher night-to-day systolic BP ratio (i.e. with lack of NBPD, r = -0.21, p=0.02). This relationship remained significant after adjusting for age and sex.

 

Conclusion:

Amongst patients with diabetes, reduced eGFR was associated with higher BP and abnormal NBPD, but not with BPV. Several factors that regulate BPV, such as autonomic function, may also influence NBPD, whilst others such as arterial stiffness are less likely to do so. Further study is needed to characterise BP fluctuations in diabetic patients with CKD, who constitute a high risk group.