Purpose: To determine the association of blood elements, selected clotting factors, and nephropathy with proliferative diabetic retinopathy (PDR) and macular edema (ME) in those with long duration type 1 diabetes.
Methods: Participants (N = 442) were seen in 2005-2007 at the 25-year follow-up of a population-based study of diabetic retinopathy, and were eligible for this analysis. Fundus photographs were graded using a standard retinopathy severity scheme. Laboratory measures included hematocrit, white blood cell and platelet counts, serum fibrinogen, interleukin-6, and von Willebrand factor.
Results: In models including duration of diabetes, hypertension, and diabetic nephropathy, only hematocrit was marginally associated with decreased odds of PDR (odds ratio 0.87; 95% confidence interval 0.74-1.01; P for trend per quintile = 0.06). Stratifying by nephropathy status, in those with and without nephropathy, there were no significant associations of any laboratory measures with PDR or ME. None of the variables we examined were associated with ME in individuals with or without nephropathy.
Conclusion: In persons with long duration type 1 diabetes, none of the blood elements or clotting factors were associated with increased odds of PDR or ME. Investigation of common pathways that lead to diabetic nephropathy and diabetic retinal outcomes should be a research priority in efforts to prevent vision-threatening complications of diabetes and nephropathy.