Time-to-effect relationships between systolic blood pressure and the risks of nephropathy and retinopathy in patients with type 2 diabetes

Aims To analyze time-to-effect relationships between systolic blood pressure (SBP) and the risks of development of nephropathy and retinopathy in patients with type 2 diabetes. Methods We retrospectively enrolled 647 patients with type 2 diabetes who first visited our hospital between 1995 and 1996, made ≥1 hospital visit per year, had been followed-up for ≥1 year, and had undergone ≥4 SBP measurements. Of these, 352 with normoalbuminuria and 516 without retinopathy were followed through June 2012. Results Nephropathy developed in 90 patients and retinopathy in 113. Hazard ratios (HRs) for time-dependent SBP-associated nephropathy and retinopathy were the highest during 1 year preceding each endpoint or censoring. The HRs for nephropathy had been steadily lower during the preceding 1–17 years, while that for retinopathy had been lower during the preceding 1–5 years and constant during the preceding 5–17 years. Conclusions The time-to-effect relationship with SBP differed for the development of nephropathy and retinopathy. The long-term effect was obvious for nephropathy and borderline for retinopathy, while the short-term effect was stronger and evident for both. Continuous SBP lowering is necessary to prevent nephropathy, whereas SBP control during the preceding 5 years seems to be important to prevent retinopathy.