Purpose To describe the relationship of retinal vascular calibre with diabetes and diabetic retinopathy in a rural population in northern China.
Methods The Handan Eye Study examined 6830 Chinese people (90.4% response rate) aged 30+ years from 13 randomly selected villages of Yongnian County, Handan city in 2006-7. Participants underwent a standardized interview and extensive examinations including retinal photography, measurement of blood pressure (BP) and fasting plasma glucose (FPG).Retinal vascular calibre was measured and summarized using a validated computer programme from digital retinal photographs. Diabetic retinopathy signs were graded from photographs using the modified Airlie House classification.
Results Of the 5148 participants with gradable retinal images and FPG results included in this study, 110 (2.1%) had KDM, 218 (4.2%) were newly diagnosed diabetes (NDM), 1923 (37.4%) had IFG and 2897 (56.3%) had NFG. After multivariable adjustment, retinal arteriolar calibre was significantly narrower in people with diabetes (153.7 μm) compared with participants with NGT (157.6μm, p = 0.02), while venular calibre was significantly wider in people with diabetes (242.1 μm) compared with participants with NGT (239.4μm, p = 0.02). One SD increase in mean arteriolar calibre was associated with lower odds of diabetes compared with NGT (odds ratio [OR] = 0.67, 95%CI = 0.52–0.86).  One SD increase in mean venular calibre was associated with higher odds of diabetes compared with NGT (odds ratio [OR] = 1.32, 95%CI =1.10–1.57).
Conclusions This study shows narrower retinal arterioles and wider venules both in diabetes and in those with diabetic retinopathy in a rural Chinese population. These findings add furtherto the concept that variations in retinal vascular caliber mayreflect early diabetic microvascular damage.