The research study was approved by the Institutional Review Board at the University of Illinois at Chicago. Prior to subjects' enrollment, the research study was explained to them, and informed consent was obtained according to the tenets of the Declaration of Helsinki. Twenty-nine subjects with a clinical diagnosis of diabetes mellitus and 22 non-diabetic control subjects (CNTL) participated in the study. Exclusion criteria included high myopia (refractive error > −6 diopter [D]), clinical diagnosis of diabetic macular edema, history of antivascular endothelium growth factor treatment, stroke or myocardial infarction (within 3 months of imaging), active angina, clinical diagnosis of glaucoma, age-related macular degeneration or retinal vascular occlusions, history of intraocular surgery, or cataract surgery performed less than 9 months prior to imaging. Control subjects underwent dilated fundus examination by retina specialists (N.P.B., F.Y.C.) to confirm retinal health. Diabetic subjects also underwent dilated fundus examination by retina specialists (J.I.L., F.Y.C., Y.I.L.) who categorized subjects into no DR (NDR [n = 17]) or non-proliferative DR (NPDR [n = 12]) groups. One eye per subject was selected based on exclusion criteria. If both eyes qualified, the eye with better image data was selected. Right-to-left eye ratios were 13:9, 12:5, and 6:6 in the CNTL, NDR, and NPDR groups, respectively. Spherical refractive errors of CNTL (−1.3 ± 2.6 D), NDR (−0.6 ± 1.9 D), and NPDR (0.0 ± 1.0 D) subjects were similar (P = 0.2). Female-to-male subject ratios were 14:8, 9:8, and 8:4 in CNTL, NDR, and NPDR groups, respectively (P ≥ 0.6). Subjects in CNTL, NDR, and NPDR groups were similar in terms of race composition (P ≥ 0.3). Mean ages of CNTL (63 ± 12 years of age), NDR (59 ± 8 years of age), and NPDR (58 ± 9 years of age) subjects also were similar (P = 0.3).