Visual Symptoms During Hypoglycemia: A Case Series

ABSTRACT Objective: To recognize visual symptoms that occur during hypoglycemia to help patients avoid severe hypoglycemic events. Methods: A series of adults with insulin-requiring diabetes were asked to complete questionnaires concerning visual symptoms during hypoglycemia (blood glucose <70 mg/dL). For patients using a continuous glucose monitoring system (CGMS), glucose levels during the time of symptoms were confirmed from downloads of their devices and meter readings when available. Pregnant women and those with an inability to complete the survey were excluded. Demographic information and type, duration, and complications of diabetes were obtained from medical record review. Results: Participants (n = 107) were 68.6% female, with a mean age of 50.4 years, duration of diabetes of 9 to 46 years, 59.2% of participants had type 1 diabetes (39% pump users) and 22 participants were using CGMS (2 of these 22 participants were excluded because of incomplete data). Of the CGMS users, 75.0% had ≥1 visual symptom, and 86.6% had glucose levels <60 mg/dL with visual symptoms. Blurred vision was the most common visual symptom reported during hypoglycemia (73.3% of all participants and 65.0% using CGMS), followed by dimness of vision (44.7%), “black spots” (37.1%), central black hole (34.3%), double vision (15.3%), and transient complete loss of vision (2.8%). Time from onset to resolution of symptoms was less than 30 minutes in 80.0% of participants. Conclusion: Visual symptoms are common during hypoglycemia but not widely appreciated. Blurred vision, common with hyperglycemia, is also seen during hypoglycemia. It is especially important for patients with poor hypoglycemic awareness to be educated to better recognize that changes in vision may indicate hypoglycemia. Abbreviations: CGMS continuous glucose monitoring system