Rapid Improvement in Blood Glucose Control in a Patient With Type 1 Diabetes and Complete Blindness Using a Continuous Glucose Monitor

PRESENTATION M.P. is a 73-year-old woman who has had type 1 diabetes since 1964. She suffered severe diabetic retinopathy, resulting in bilateral enucleation of the eyes with placement of ocular prostheses. The patient’s husband has traditionally checked her blood glucose levels and administered some of her insulin injections. However, her husband is often away from home during the day, and M.P. does occasionally monitor her own blood glucose with a “talking” glucose meter and can administer insulin with an insulin pen device by counting the number of clicks she hears when dialing the units of insulin. During a clinic visit, her diabetologist noted frequent hypoglycemia on the glucose meter download, especially during the day when the patient herself was administering insulin injections. Her A1C was 6.5%. She has fairly severe hypoglycemia unawareness, and she was often found hypoglycemic by her husband in the afternoon when he returned home or was found by neighbors as she wandered in her neighborhood. M.P. admitted to correcting high blood glucose levels aggressively during the day without consistently following her correction-dose ratio, as well as to treating hypoglycemia with a whole candy bar or meal. She reported that she had done this for many years and, despite education on the subject, had not made significant changes in her behavior. The patient was placed on the Dexcom Seven Plus (San Diego, Calif.) continuous glucose monitoring (CGM) system for 7 days and was instructed on its use by a certified diabetes educator. She required assistance from her husband in calibrating the CGM. She was taught to audibly recognize high blood glucose alerts (set at 180 mg/dl) by a double-beep from the CGM device and low blood glucose alerts (set at 80 mg/dl) by a triple-beep from the monitor. M.P. was able to quickly learn after a few days that she frequently fluctuated rapidly between hyperglycemia alarms and hypoglycemia alarms and was likely giving herself an overly aggressive correction dose of insulin when her glucose was high and eating too much when it was low. The patient made appropriate changes on her own and was able to improve her average blood glucose from 162 mg/dl during the first 4 days of CGM use to 138 mg/dl during the next 4 days. Her glucose variability improved, as measured by a decrease in the standard deviation from ± 61 to ± 39 mg/dl. The percentage of time spent in the high glucose range (> 180 mg/dl) improved from 35 to 18%, and the percentage of time spent in the low glucose range (< 80 mg/dl) improved from 9 to 3% with no episodes of severe hypoglycemia (Figures 1 and 2).