Blood filterability and hemoglobin-oxygen affinity in diabetic patients with and without retinopathy.

The relationship between the presence of retinal microangiopathy and changes in blood filterability was investigated in 30 adult diabetic patients with variable known duration of the disease. The degree of diabetic control was assessed by plasma glucose and hemoglobin A1 levels; oxygen affinity of hemoglobin was also evaluated. Retinopathy lesions of graded severity were present in 24 of the 30 diabetic patients; no other relevant complications of diabetes or associated pathology were observed. The diabetic patients had higher plasma glucose (11.82 +/- 1.75 vs 3.88 +/- 0.43 mmol/l, p less than 0.001) and hemoglobin A1 values 12.26 +/- 1.95 vs 7.97 +/- 0.94%, p less than 0.001) but lower filterability (12.09 +/- 1.37 vs 15.80 +/- 0.83 microliter/sec, p less than 0.001) than the control subjects. In the diabetic patients, plasma glucose was significantly correlated to HbA1. The hemoglobin oxygen affinity decreased with age and reduction of blood filterability was more perceptible as the severity of retinopathy increased. It is concluded that reduced blood filterability might contribute to the development and progression of retinopathy in diabetics.