Hyperreflective dots (HRD) are activated retinal microglial cells induced by retinal inflammation in diabetic patients. This study was conducted to compare the HRD count of normal and diabetic subjects; to determine the correlation between hemoglobin A1c (HbA1c) levels and HRD count; to determine HbA1c cut-off levels for the appearance of HRD in diabetic patients. A cross-sectional study was conducted among normal and diabetic patients. Fundus photos, SD-OCT images and HbA1c levels were taken. A total of 25 normal subjects, 32 diabetics without retinopathy and 26 mild-to-moderate nonproliferative diabetic retinopathy (NPDR) diabetics were recruited. There was a statistically significant difference between the mean count of HRD among the normal group, the diabetic without retinopathy group and the mild-to-moderate NPRD group. The mean HRD count in the inner retina layer was significantly higher compared to the outer retina layer. There was a significant linear relationship between the HbA1c levels and HRD count. Using the receiver operating curve, the HbA1c level of 5.4% was chosen as the cut-off point for the appearance of HRD. The positive linear correlation between the HbA1c levels and the appearance of HRD may indicate that hyperglycemia could activate retina microglial cells in diabetic patients.