The Role of Blood Pressure Variability in the Development of Nephropathy in Type 1 Diabetes

OBJECTIVE - Increases in blood pressure and visit-to-visit variability have both been found to independently increase the likelihood of cardiovascular events in nondiabetic individuals. This study has investigated whether each may also influence the development of microvascular complications in type 1 diabetes by examining data from the Diabetes Control and Complications Trial (DCCT). RESEARCH DESIGN AND METHODS - Using binary longitudinal multiple logistic regression, mean systolic (SBP) and diastolic (DBP) blood pressure as well as annual visit-to-visit variability (SD.SBP and SD.DBP, respectively) was related to the risk of the development/progression of nephropathy and retinopathy in initially normotensive subjects who did not become pregnant during the DCCT. RESULTS - Mean SBP and SD.SBP were independently predictive of albuminuria (odds ratio 1.005 [95% CI 1.002-1.008], P < 0.001 and 1.093 [1.069-1.117], P < 0.001, respectively, for 1 mmHg change), although SBP variability did not add to mean SBP in predicting retinopathy (0.999 [0.985-1.013], P = 0.93). DBP variability was also independently predictive of nephropathy (1.102 [1.068-1.137], P < 0.001) and not of retinopathy (0.991 [0.971-1.010], P = 0.37). Mean SBP was poorly related to SD.SBP (r(2) < 0.01) as was mean DBP with SD. DBP (r(2) < 0.01). CONCLUSIONS - Visit-to-visit variability in blood pressure consistently independently added to mean blood pressure in predicting the risk of nephropathy, but not retinopathy, in the DCCT. This observation could have implications for the management and treatment of blood pressure in patients with type 1 diabetes.