Continuous glucose monitoring alarms in adults with type 1 diabetes: user characteristics and the impact of hypoglycemia and hyperglycemia alarm thresholds on glycemic control

Background: Few studies have evaluated the implications of the alarm thresholds of continuous glucose monitoring systems for individuals with diabetes. The present study aimed to investigate the influence of hypoglycemia and hyperglycemia alarm thresholds on glycemic control in adults with type 1 diabetes and the characteristics of patients who use these alarms more frequently. Methods: This observational cross-sectional study included 873 users of the FreeStyle Libre 2 system (501 men, median age 48 years, range 18-90 years) with type 1 diabetes from a single center. We investigated the role of demographic and metabolic factors on the use of the alarms and the impact of hypoglycemia and hyperglycemia alarms and their thresholds on glycemic control. Results: Alarm users were older than non-users (median age 49 years versus 43 years, respectively; p<0.001). The hypoglycemia alarms were set by 76.1% of women and by 69.1% of men (p=0.022). The hypoglycemia alarms reduced hypoglycemia features and glucose variability, although at the expense of shorter time in range. The higher the hypoglycemia alarm threshold, the greater these effects. The hyperglycemia alarms were effective in reducing hyperglycemia and lowering the glucose management indicator, although at the expense of a greater tendency to hypoglycemia. The lower the hyperglycemia alarm threshold, the greater these effects. Conclusions: Continuous glucose monitoring alarms contribute to better glycemic control. However, hypoglycemia and hyperglycemia alarms have advantages and disadvantages. Adults with type 1 diabetes should explore, under medical supervision, which alarm thresholds will best help them achieve their individual glycemic goals.