Elevated blood pressure (BP) is associated with an increased risk of renal damage in patients with Type 2 diabetes, especially if they have poor glycaemic control, study findings suggest.
“Our results support strong consideration for treatment of higher levels of systolic hypertension for renal protection”, say study author Robert Anderson (Veterans Affairs Medical Center, Omaha, Nebraska, USA) and team.
Their findings emerge from a post-hoc analysis of data from the Veterans Affairs Diabetes Trial (VADT), including 1374 patients with complete albumin-to-creatinine ratio (ACR) data and 1649 with complete estimated glomerular filtration rate (eGFR) data. The patients were aged an average of 60.4 years.
During up to 7 years of follow-up, the likelihood of patients experiencing a deterioration in ACR rose with increasing on-study systolic (S)BP but not diastolic (D)BP. Relative to those with an on-study SBP between 105 and 129 mmHg, patients with SBP of 130 to 139 mmHg had a 1.88-fold increased risk of a deterioration in ACR and those with SBP of 140 mmHg or more had a 2.52-fold increased risk.
Patients’ BP was not significantly associated with worsening eGFR; however, there was an interaction with glycated haemoglobin level such that there was an increased risk of worsening eGFR in patients with systolic hypertension and poor glycaemic control.
Pulse pressure (PP) was also associated with renal outcomes, with the likelihood of ACR worsening significantly increasing at a PP of 60 mmHg or higher, at a 2.38-fold increase relative to a PP of 40–49 mmHg. By contrast, the risk was reduced by a significant 64% in patients with PP lower than 40 mmHg.
Because there was no sign of an association between DBP and renal outcomes, the researchers attribute the effect of PP on renal outcomes to its association with SBP.
“Given the age of our study population, the increased PP may represent arterial stiffening with increased SBP without elevation of the DBP as a major contributor to this finding”, they comment in Diabetes Care.
When analysed as continuous variables, on-study SBP and PP, but not DBP, were significantly associated with both ACR and eGFR worsening. Notably, baseline PP was also associated with eGFR worsening.
The team concludes that the risk of renal damage in diabetes patients emerges at a SBP of between 130 and 139 mmHg, but a SBP of 140 mmHg reflects a “more critical” level when eGFR may also be affected.
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