The results of a recent study have shown that a simple blood test can identify patients with type 1 diabetes who are at high risk of developing productive retinopathy.
Multivariate analysis showed that for every 1g/dL increase in haemoglobin was associated with a 29% increase in the risk of retinopathy in men and 10% in women with type 1 diabetes, said Dr Trevor of the University of Pittsburgh. «This is the first study to show that high haemoglobin levels could be a predictor of the development of productive diabetic retinopathy,» the researchers noted.
The study used data from 426 participants in a larger epidemiological study of diabetes complications, which began in the late 1980s. The total duration of follow-up was about 18 years.
At baseline, the average age of the participants was about 25 years and the average duration of diabetes was 17 years. During the study 48% of participants experienced productive diabetic retinopathy. Of note, hemoglobin levels were 16.5 g/dL in those who developed retinopathy versus 16.1 g/dL in those who did not (P=0.009).
Other factors associated with the occurrence of retinopathy were the presence of nephropathy, albumin secretion rate, total and LDL-cholesterol, diastolic (but not systolic) blood pressure and glycosylated haemoglobin levels. Of these factors, only diastolic blood pressure and glycosylated hemoglobin remained as predictors of retinopathy in multivariate analysis for both sexes.
Each 1% increase in haemoglobin was associated with a relative risk of retinopathy of 1.30 in men and 1.32 in women. The relative risk of retinopathy for each 1mmHg increase in diastolic pressure was 1.03 in men and 2.28 in women. Diastolic pressure was a predictor of retinopathy in women (relative risk 1.03 per 1mmHg increase) but not in men. Albumin secretion rate was a predictor in men (relative risk 1.34 per 1mmg/min increase) but not in women.
To date, the importance of haemoglobin has been focused on low levels - i.e. anaemia - in end-stage renal failure. The results of the present study may be of particular clinical importance, since they may identify the pathogenetic processes of productive diabetic retinopathy and influence its treatment. High haemoglobin levels are potentially involved in the development of retinopathy through effects on testosterone levels, growth factors and blood glucose.
