Blood Pressure Variability and Nocturnal Dipping in Diabetic Patients With and Without Chronic Kidney Disease

Background: Both increased blood pressure variability (BPV) and lack of nocturnal blood pressure dipping (NBPD) are independently associated with excess mortality in patients with diabetes mellitus. We hypothesised that patients with diabetes and CKD have higher BPV and are more likely to demonstrate a lack of nocturnal blood pressure dipping, than their counterparts without CKD. Methods: Clinical and biochemical data were collected from 124 patients attending diabetes clinics at Austin Health, Melbourne Australia. Stage 3 to 5 CKD (from here on referred to as “CKD”) was defined by a CKD-EPI eGFR of 90% suggested abnormal NBPD (“non dippers”). Results: Thirty-four patients (27%) had CKD. The mean±SD 24h systolic blood pressure was higher in patients with CKD than those without (135±16mmHg vs. 129±13mmHg respectively, p=0.03), and there was a negative correlation between eGFR and 24h systolic BP (r = -0.21, p=0.02). 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). This relationship remained significant after adjusting for age and sex. Conclusion: Amongst patients with diabetes, reduced eGFR was associated with higher blood pressure and abnormal NBPD, but not with BPV. Further study is needed to characterise blood pressure fluctuations in diabetic patients with CKD, who constitute a high risk group.