A systematic review of the association of diabetic retinopathy and cognitive impairment in people with Type 2 diabetes

A systematic review of studies reporting data on the relationship between diabetic eye disease and cognitive impairment in Type 2 diabetes was conducted. The increase in cognitive impairment has mirrored the global increase in diabetes. The aim of the systematic review was to determine the level of association between diabetic retinopathy and cognitive impairment. Item selection, data extraction and critical appraisal were undertaken using standard procedures and independently verified by two researchers. 3 out of 10 potentially relevant studies were included. All studies showed a level of association between diabetic retinopathy and cognitive impairment, suggesting a near threefold increased risk of cognitive impairment in patients with diabetic retinopathy compared to those without. An association of cognitive impairment and severity of diabetic retinopathy was found in males. Diabetic retinopathy was more strongly linked to impairment in the cognitive domains of verbal learning and recent memory. An increased risk of cognitive impairment in patients with diabetic retinopathy was found in the reviewed studies. However, the relationship of severity of diabetic retinopathy and cognitive impairment has not been established. Further studies with standardized measurements for cognitive impairment and diabetic retinopathy are required to delineate this relationship and the role of other factors in this relationship.