Background: To evaluate the association between continuous glucose monitoring (CGM)-derived glycemic variability indicators and early microvascular changes of the retina and choroid in nondiabetic individuals.Methods: Community-based individuals at high risk for type 2 diabetes (T2DM) underwent detailed assessments including oral glucose tolerance tests (OGTT), CGM, and ophthalmic imaging including optical coherence tomography angiography (OCTA). Based on the mean amplitude of glycemic excursions (MAGE), 338 OGTT-confirmed nondiabetic participants were categorized as having normal glucose fluctuation (NGF) or abnormal glucose fluctuation (AGF). Between-group differences in foveal avascular zone (FAZ), blood flow density, and thickness in retina and choroid were analyzed. Multiple linear regression analysis was used to analyze the correlation between CGM metrics and blood flow density in retina and choroid.Findings: Compared with the NGF group (264 eyes from 264 participants), the AGF group (74 eyes from 74 participants) showed lower retinal blood flow density in the central (P=0.001) and parafoveal nasal (P=0.022) regions of the superficial layer, and in the parafoveal superior region of the deep layer (P<0.001). In the choroid, the volume area ratio of large vessels (CVV/a) was reduced, whereas the choroidal vascular index (CVI) was increased in the AGF group. Choroidal thickness was decrease in all regions among individuals with AGF. CGM metrics such as MAGE and coefficient of variation (CV) were negatively correlated with the retinal and choroidal blood flow density.Interpretation: Increased glycemic variability even in nondiabetic adults is associated with reduced blood flow density and decreased choroidal thickness.