The risk of diabetic renal function impairment in the first decade after diagnosed of diabetes mellitus is correlated with high variability of visit-to-visit systolic and diastolic blood pressure: a case control study

Background: The variability of visit-to-visit (VVV) in systolic blood pressure (SBP) and diastolic blood pressure (DBP) is proved as a predictor of renal function deterioration in patients with non-diabetic chronic kidney disease. The purpose of this study was to investigate the relationship of the variability in SBP and the magnitude of renal function impairment for normal renal function patients in the first 10-years diagnosed with type II diabetes mellitus (DM). Methods: We retrospectively reviewed the electronic medical records of 789 patients who were first diagnosed with diabetes mellitus during 2000-2002 and regularly followed for 10 years with a total of 53,284 clinic visits. The stages of Chronic Kidney Disease (CKD) of every patient were determined using estimated glomerular filtration rate. The occurrence of nephropathy was defined in those patients whose CKD stages elevated equal or larger than three. Results: Patients were categorized according to the VVV of systolic and diastolic BP into three groups. Patients with high VVV of both SBP and DBP had a 2.44 fold (95% CI: 1.88-3.17, p < 0.001) increased risk of renal function impairment compared with patients with low VVV of both SBP and DBP. Risk of renal function impairment for patients with high VVV of either SBP or DBP had a 1.43-fold increase (95% CI: 1.08-1.89, p = 0.012) compared with patients with low VVV of both SBP and DBP. Cox regression analysis also demonstrated that every 1-year increase of DM diagnosed age significantly raised the risk of renal function impairment with a hazard ration of 1.05 (95% CI: 1.04-1.06, p < 0.001). Conclusions: Not only VVV of SBP but also VVV in DBP is correlated with diabetic nephropathy in the first decade for patients diagnosed with type 2 DM.