Aortic stiffness and ambulatory blood pressure as predictors of diabetic kidney disease: a competing risks analysis from the Rio de Janeiro Type 2 Diabetes Cohort Study

Aims/hypothesis: Diabetic kidney disease (DKD) is a microvascular complication associated with poor control of blood glucose and BP. We aimed to evaluate the predictors of development and progression of DKD in a cohort of high-risk individuals with type 2 diabetes, placing emphasis on ambulatory BP and arterial stiffness.

Methods: In a prospective study, 629 individuals without advanced renal failure had their renal function evaluated annually over a median follow-up period of 7.8 years. Ambulatory BP was monitored and aortic stiffness was assessed by carotid-femoral pulse wave velocity at baseline. Multivariate competing risks analysis with all-cause mortality, using the Fine and Gray approach, was used to examine the independent predictors of development and progression of DKD, a composite of development or progression of abnormal albuminuria and worsening of renal function (doubling of serum creatinine or progression to end-stage renal disease).

Results: At baseline, 197 individuals had DKD. During follow-up, DKD developed or progressed in 195 individuals, abnormal albuminuria developed or progressed in 125 individuals and renal function deteriorated in 91. After adjustments for baseline albuminuria and renal function, age, sex, diabetes duration and use of renin-angiotensin antagonists, poorer control of blood glucose (HR 1.17; 95% CI 0.98, 1.40; p = 0.09 for each 1 SD increment in mean first-year HbA_1c), higher ambulatory systolic BP (HR 1.28; 95% CI 1.09, 1.50; p = 0.003, for each 1 SD increase in daytime systolic BP [SBP]) and increased aortic stiffness (HR 1.16; 95% CI 1.00, 1.34; p = 0.05) were independent predictors of development or progression of DKD. At baseline, ambulatory BP was a stronger predictor than BP measured in the clinic. Aortic stiffness predicted abnormal albuminuria development or progression (HR 1.26; 95% CI 1.02, 1.56; p = 0.036) whereas ambulatory BP was a stronger predictor of renal function deterioration (HR 1.32; 95% CI 1.09, 1.60; p = 0.005 for daytime SBP).

Conclusions/interpretation: Poor blood glucose and BP control and increased aortic stiffness were the main predictors of development or progression of DKD; ambulatory SBP was a better predictor than BP measured in the clinic. Ambulatory BP monitoring and assessment of aortic stiffness should be more widely used in clinical type 2 diabetes management.