Factors associated with diabetic nephropathy in subjects with proliferative retinopathy

Abstract

Aim: The purpose was to compare the phenotype of subjects with type 2 diabetes mellitus having both retinopathy and nephropathy with that of subjects having retinopathy but no nephropathy. Methods: We recruited 196 subjects; 85 were normoalbuminuric (controls), whilst cases consisted of patients with micro- (n = 66) or macroalbuminuria (n = 45). Both groups underwent 24-h blood pressure (BP) monitoring and were analysed regarding markers of the metabolic syndrome, inflammation (erythrocyte sedimentation rate [ESR] and highsensitivity CRP [hsCRP]) and insulin resistance (HOMA-IR). Results: Cases had significantly higher white cell count (P = 0.02), ESR (P<0.001), platelets (P = 0.02), triglycerides (P = 0.001), uric acid (P<0.001), daytime and night-time systolic BP (P = 0.001 & P = 0.001, respectively), diastolic BP (P = 0.007 & P = 0.001), pulse pressure (P = 0.02 & 0.055) and mean arterial pressure (P = 0.001 & P<0.001) in univariate analysis. Cases had a lower haemoglobin level (P = 0.01) and estimated glomerular filtration rate (eGFR) (P = 0.002) in comparison with controls. Multivariate analysis showed that night-time diastolic BP (P = 0.002, B = 1.057), platelet count (P = 0.018, B = 1.007) and eGFR (P<0.001, B = 0.097) are independent predictors of diabetic nephropathy. Platelet count (P = 0.045, B = 1.006), night-time mean diastolic BP (P = 0.029, B = 1.042) and eGFR (P = 0.001, B = 0.975) were also found to be independent predictors of the occurrence of microalbuminuria. Conclusions: By analysing factors associated with diabetic nephropathy rather than microvascular disease in general, this study provides evidence that night-time diastolic BP and a relative increase in platelet count are associated with incipient diabetic nephropathy.