Red blood cell distribution width and diabetes-associated complications

Abstract

Aim: Red blood cell distribution width (RDW) is a marker of cardiovascular morbidity and mortality. However, there is little data on the relationship between RDW and diabetes-associated complications. The aim was to investigate whether there is any association between RDW, nephropathy, neuropathy and peripheral arterial disease (PAD) in a type 2 diabetic population. Methods: This study included 196 diabetic patients with proliferative diabetic retinopathy. All subjects were investigated for diabetic nephropathy, diabetic neuropathy and PAD. Participants underwent 24-h blood pressure monitoring and were analysed for markers of the metabolic syndrome, inflammation, and insulin resistance. Results: 57% of the participants had diabetic nephropathy, 46% had diabetic neuropathy while 26% had PAD. No significant association was found between RDW, diabetic neuropathy and PAD (p = NS). However, RDW was strongly associated with diabetic nephropathy (p = 0.006), even following adjustment for potential confounding variables. Multivariate logistic regression analysis showed RDW (odds ratio [OR] 1.64, 95% confidence interval [CI] 1.15–2.35, p = 0.006), estimated glomerular filtration rate (OR 0.98, 95% CI 0.96–0.99, p < 0.001), night-time diastolic blood pressure (OR 1.07, 95% CI 1.03–1.11, p = 0.001) and erythrocyte sedimentation rate (OR 1.03, 95% CI 1.004–1.05, p = 0.019) to be independently associated with diabetic nephropathy. Conclusions: This is the first study to report lack of association between RDW, neuropathy and PAD in subjects with type 2 diabetes mellitus. More importantly, RDW was shown to be significantly associated with diabetic nephropathy in a type 2 diabetic population with advanced proliferative retinopathy independent of traditional risk factors, including diabetes duration and glycaemic control.