Research shows that variations in SBP can negatively impact the development and progression of diabetic nephropathy in type 2 diabetes patients….
Recent data suggests that visit-to-visit variability in SBP is associated with the development of diabetic nephropathy in patients with type 1 diabetes and with albuminuria in normal patients. This is of concern because elevated urinary albumin excretion rate (UAE) has been associated with an increased risk of cardiovascular mortality and the progression of CVD. A new study therefore looked to determine whether the same is true of visit-to-visit variability in SBP in patients with type 2 diabetes.
A retrospective cohort study was performed on 354 participants from April 2008- September 2012. These patients were recruited from the outpatient clinic at the Kyoto Prefectural University of Medicine. Nephropathy in these patients was graded by the following: normoalbuminuria (UAE<30mg/g Cr), microalbuminuria (UAE 30-300mg/g Cr), and macroalbuminuria (>300mg/g Cr). Blood pressure was measured at every visit during a 1 year period, and a coefficient of variation (CV) of SBP was calculated. Urinary albumin and Cr concentrations were measured by performing an immunoturbidimetric assay using an early spot urine collection. Development of albuminuria was classified as a UAE≥30mg/g Cr.
The mean CV of SBP for this group of patients was calculated to be 8.0±4.0%. The results showed the change in UAE to be 16.1±28.7mg/g Cr. Of the 218 patients that had normoalbuminuria at baseline, 28 patients developed albuminuria. The statistical analysis showed the average of SBP or the CV of SBP to be independently associated with change in UAE, while average SBP, CV of SBP, total cholesterol, and triglycerides were found to be associated with an increased likelihood of development of albuminuria.
This study has several limitations. The first of these is that this study was done using Japanese men and women, and therefore may not be applicable to other ethnicities. The number of patients studied was small, and the follow-up period was short. Larger prospective studies with a longer follow-up time and more diverse patient population would help to better assess the relationship studied here. The mechanism by which blood pressure variability impacts vascular damage and organ damage is also unclear.
Overall, the results of this study indicate that there is a relationship between SBP variability from visit to visit and the development and progression of nephropathy in these patients with type 2 DM.
- Visit-to-visit variability in SBP was found to be a risk factor for the development of albuminuria and change in UAE in patients with type 2 diabetes.
- Further research is needed to uncover the mechanism by which this occurs, and to evaluate this relationship in a larger, more ethnically diverse patient population.
Okada, H. et al. "Visit-to-Visit Blood Pressure Variability Is a Novel Risk Factor for the Development and Progression of Diabetic Nephropathy in Patients With Type 2 Diabetes" Diabetes Care. 2014;36(7):1908-1912.