There is much evidence that localized low grade inflammatory processes may contribute to the microvascular complications of type 1 and type 2 diabetes mellitus including sight-threatening diabetic retinopathy. Some biomarkers for inflammation have been found to be elevated in diabetes patients and correlations between those biomarkers and the severity of diabetic complications have been found in the last years. The relation between this low grade inflammation and the microvascular changes observed in diabetic retinopathy is, however, not well characterized.

In the present study patients with different stages of non-proliferative diabetic retinopathy will be included. Several markers of inflammation will be measured from blood samples. These markers will be related to vascular factors including flicker-induced vasodilatation as a marker of endothelial dysfunction and perifoveal leukocyte velocity and density as measured with the blue field entoptic phenomenon. In addition, the ophthalmologic status of the patients will be assessed according to the Modified Airlie House classification.

A multiple regression model will be employed to study the association between the different methods.

Inclusion Criteria:

• Patients with type 1 diabetes mellitus with duration of > 1 year
• Men and women, age ≥ 18, nonsmokers
• Body mass index between 16 and 30 kg/m²
• Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant or diabetes-related
• Mild, moderate or severe non-proliferative diabetic retinopathy

Exclusion Criteria:

• Abuse of drugs or alcoholic beverages
• Participation in a clinical trial in the 3 weeks preceding the study
• Treatment with anti-inflammatory drugs in the 3 weeks before the study day
• Symptoms of a clinically relevant illness in the 3 weeks before the study day
• Blood donation or equivalent blood loss in the 3 weeks before the study day
• Other ocular pathologies than non-proliferative diabetic retinopathy
• Ametropia > 6 dpt
• History or family history of epilepsy
• Pregnant or lactating women

outpatients