Low BP could be renoprotective in type 1 diabetes
medwireNews: Observational data suggest that a low blood pressure (BP) target may still be necessary for patients with type 1 diabetes.
Among 1375 patients enrolled in the Epidemiology of Diabetes Interventions and Complications (EDIC) study, the risk for renal outcomes was reduced in those who had BP “significantly below the current treatment guidelines,” say Elaine Ku (University of California, San Francisco, USA) and study co-authors.
The patients were aged an average of 27 years at the time of enrolment into the parent randomized Diabetes Control and Complications Trial (DCCT) study. They were followed up for an average of 6.5 years in DCCT and an additional 24 years in EDIC, during which 169 developed macroalbuminuria and 84 developed stage 3 chronic kidney disease (CKD).
But patients whose systolic BP (SBP) was lower than 120 mmHg during follow-up were a significant 41% less likely to develop macroalbuminura and 68% less likely to develop stage 3 CKD than those whose BP was 130–140 mmHg.
The reference BP range is in line with current US guidelines, from which the previous 130/80 mmHg BP target for diabetic patients was recently dropped based largely on “the lack of solid trial-based evidence” supporting it.
However, these trials mainly involved patients with type 2 diabetes, so Ku et al suggest the effects of BP could be different in type 1 diabetes patients, “given the younger age of disease onset, the earlier diagnosis, and the lower prevalence of comorbidities, such as obesity at the time of type 1 diabetes onset.”
The association between BP and renal outcomes was independent of multiple variables, including changes in factors such as glycated hemoglobin, body mass index, and medication use over time.
The researchers stress the importance of accounting for changes over time. “In fact, we found that baseline SBP and [diastolic] BP values at DCCT entry were poorly predictive of the long-term risk of adverse renal outcomes,” they write in Diabetes Care.
Diastolic BP was not significantly associated with renal outcomes after adjustment for confounders, although there was a trend towards a protective effect below 70 mmHg.
Ku and team stress that low SBP appeared to be protective even in patients who received intensive glycemic control in DCCT.
“We believe this finding to be important, as the traditional focus in type 1 diabetes research and clinical practice has been on the effects of intensive glycemic control,” they write.
They believe it “supports the need for future interventional studies, because BP treatment may be less costly and more achievable than other treatment options.”
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