891-P: Detecting Dawn Phenomenon in T1D with Continuous Glucose Monitoring and Activity Tracking

Background and Aims: Dawn phenomenon (DP) refers to the morning rise in glucose levels observed in individuals with diabetes. While continuous glucose monitoring (CGM) may detect rates of change (ROC) in sensor glucose (SG) levels, ensuring that DP is not due to unannounced carbs can be challenging. Hence, a combination of CGM and activity data were used to identify true DP. Method: MiniMed™ 530G system data were uploaded between 6/2017-10/2017 by 33 individuals. Corresponding heart rate, steps, and metabolic equivalents (METs) were acquired with Fitbit® Charge 2™. Nights without carb or bolus entry from 12-6AM were analyzed. Nights with SG ROC >0.28mg/dL/min (ROC between peak and nadir) and no activity (METs 1.5) ±30min of nadir were identified as involving unannounced carb (UC); and those with no nadir were identified as ideal. Results: Individuals had 26 nights with DP, 27 nights with UC, and 39 ideal nights and the Table shows differences in the features related to each. The ROC of SG rise due to DP was lower, took longer time to reach peak, and tended to have a higher SG at nadir when compared with UC. Conclusion: Dawn phenomenon can be identified and characterized in real-world conditions using CGM and fitness tracking. Detecting DP may help improve nocturnal and early morning glycemic management. Disclosure S. Abraham: Employee; Self; Medtronic. D. Kang: None. Y. Zhong: Employee; Self; Medtronic. P. Agrawal: None. T.L. Cordero: Employee; Self; Medtronic. R. Vigersky: Employee; Self; Medtronic.