abstract
- Continuous subcutaneous insulin infusion (CSII) programming for an early morning increase in insulin delivery is frequently recommended to counteract the rise in glucose prior to breakfast (dawn phenomenon). However, both the effectiveness and safety of this approach have not been tested in the ambulatory setting. Using continuous glucose monitoring, we investigated the safety and effectiveness of early morning CSII programming for management of the dawn phenomenon in subjects with type 1 diabetes.We conducted a controlled, observational, 8-month longitudinal study of type 1 diabetic patients (N = 40). Reproducibility of the dawn phenomenon was determined in subjects treated with multiple daily injections of insulin (n = 12) and those on CSII who did not program an early morning increase in insulin delivery (CSII nonprogrammers; n = 8). The effects of early morning CSII programming were determined by comparing rates of the dawn phenomenon and hypoglycemia in CSII nonprogrammers versus CSII users who programmed an early morning increase in insulin delivery (CSII programmers; n = 20).The dawn phenomenon occurred in all tested subjects to a variable extent (median rate, 56% of nights). CSII programming was not associated with a reduction in the occurrence of the dawn phenomenon (42%) compared to nonprogrammers (48%) (P = .47) nor in the magnitude of the dawn phenomenon. Hypoglycemia occurred more frequently in the CSII programmers (37%) compared with nonprogrammers (18%) (P = .001).The dawn phenomenon occurs unpredictably; therefore, early morning CSII programming for a fixed increase in early morning insulin delivery is ineffective and may be hazardous to the patient.