Serum Apolipoproteins Are Associated With Systemic and Retinal Microvascular Function in People With Diabetes

Serum apolipoprotein (apo)AI and-B have been shown to be associated with diabetic retinopathy, but the underlying mecha-nisms are unclear. We investigated whether apoAI and apoB levels are associated with measures of systemic and retinal microvascu-lar function in patients with diabetes. We recruited 224 diabetic patients (85 type 1 and 139 type 2) and assessed serum lipids and lipoproteins from fasting blood, skin responses to sodium nitro-prusside (endothelium independent) and acetylcholine (ACh) (endothelium dependent) iontophoresis, flicker-light–induced reti-nal vasodilatation, and retinal vascular tortuosity. After adjustment for age and sex, every SD increase in apoAI level was associated with ACh-induced skin perfusion (mean change 1.27%; P, 0.001 for apoAI) and flicker-light retinal arteriolar vasodilatation (0.33%; P = 0.003) and was associated inversely with arteriolar tortuosity (22.83 3 1025; P = 0.044). Each SD increase in apoB was associ