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Antihistamines reduce blood-retinal barrier permeability in type I (insulin-dependent) diabetic patients with
T W Gardner1, A W Eller, T R Friberg
1Department of Opthalmology, Penn State University College of Medicine, Hershey 17033, USA.
Purpose:
To determine if histamine receptor stimulation mediates increased blood-retinal barrier (BRB) permeability in patients with diabetic retinopathy, as it does in experimental diabetes.
Methods:
Fourteen patients with type I (insulin-dependent) diabetes and mild nonproliferative diabetic retinopathy were treated with combined astemizole, 20 mg, and ranitidine, 600 mg, or an identical placebo for 6 months in a double-masked fashion. Blood-retinal barrier permeability was measured by vitreous fluorometry at baseline and at 3 and 6 months.
Results:
Permeability was significantly reduced in the group treated with antihistamines (P < 0.05) compared with the placebo group. There were no concomitant significant changes in systemic arterial blood pressure or HbA1c values.
Conclusion:
These pilot data suggest that histamine receptors influence permeability of the BRB in human diabetes. Further studies of the effects of antihistamines on diabetic retinopathy are warranted.