Impact of early-morning administration of rapid-acting insulin on the increase in blood glucose levels related to the dawn phenomenon in individuals with type 1 diabetes.

Aims/Introduction: An early-morning elevation of blood glucose levels known as the dawn phenomenon and consequent postbreakfast hyperglycemia occur in some individuals with type 1 diabetes (T1D). Whereas insulin pump therapy can mitigate this phenomenon, some individuals prefer or are limited to alternative treatments. We have now assessed the effectiveness of early-morning administration of rapid-acting insulin for amelioration of the dawn phenomenon in individuals with T1D. Materials and Methods: Thirteen individuals with T1D who experienced the dawn phenomenon as determined by continuous glucose monitoring (CGM) and who received a small dose of rapid-acting insulin on waking were included in this retrospective study. We evaluated the change in sensor glucose levels during a 2-h period from before to after breakfast consumed at 0700 h. The change in blood glucose levels during additional time intervals, average daily sensor glucose values, CGM indices, and insulin dose were also evaluated. Results: The early-morning administration of 0.5-1 unit of rapid-acting insulin was associated with a significant reduction in 2-h glucose variability between before (0700 h) and after breakfast from a median of 90.7-51.0 mg/dL. The glucose variability from 0300 to 0700 or 0900 h was also significantly decreased, from 67.7 to 29.0 mg/dL and from 172.5 to 78.3 mg/dL, respectively. Average sensor glucose levels throughout the day were significantly reduced (from 192.7 to 156.7 mg/dL), as was the daily total insulin dose. Conclusion: Early-morning administration of rapid-acting insulin effectively managed the dawn phenomenon and subsequent postbreakfast hyperglycemia in individuals with T1D. Supplementary Information: The online version contains supplementary material available at 10.1007/s13340-024-00709-6.