P1.15: Higher Day Time Rate of Systolic Blood Pressure Variation is Associated with Reduced Retinal Arteriolar Diameter in Non-Diabetic, But Not in Diabetic, Individuals

Background Although Type 2 diabetes (T2DM) is associated with retinal vascular disease, the underlying pathophysiological mechanisms are unclear. Reduced retinal arteriolar diameter has been linked to high clinic blood pressure (BP) but the role of more sensitive measures of BP control have never been assessed. This study aimed to determine the relationship between retinal arteriolar diameter and 24 hour ambulatory BP (including BP variability) in people with and without T2DM. Methods Digitized retinal photographs were analysed to quantify retinal arteriolar diameters in 37 non-diabetic (aged 53±10 years; 48.2% male) and 29 T2DM (aged 60±9 years; 48.6% male) participants. Daytime rate of systolic BP variation (BPV) was derived from 24 hour ambulatory BP as the 3-hour moving average for the slope of the change in systolic BP between each systolic BP reading over time. Results There was a non-significant trend for patients with T2DM to have greater BPV compared with non-diabetics (35.9±7.1 versus 32.6±6.6; p=0.08). BPV was significantly and negatively associated with retinal arteriolar diameter in non-diabetics alone (β=−0.006, p=0.03), but not in people with T2DM (β=0.004, p=0.402), even after adjusting for age, body mass index and ambulatory systolic BP (either night time, day time or 24 hour systolic BP). Conclusions BPV was inversely related to retinal arteriolar diameter only in people without T2DM. This suggests that mechanisms underlying retinal vascular disease may differ between people with and without T2DM, with the rate of BP variation possibly being an important factor.