The use of CGM to identify type 1 diabetic patients with hypoglycemia problems and its impact for avoidance of biochemical hypoglycemia.

Abstract

This cross-over study used a CGM system (DexCom SEVEN PLUS CGM). In a randomized order, participants had either no access (CGM blind) or real time access to current glucose data (CGM open). One objective was to analyze if type 1 diabetic patients with hypoglycemia problems (at least one episode requiring third party assistance) could be identifi ed by the use of the blinded CGM data. We also analyzed the impact of CGM use on biochemical hypoglycemia. Type 1 diabetic patients with hypoglycemia problems had signifi cant longer diabetes duration (17.0 vs. 11.0 yrs.), a higher unawareness score (4.0 vs. 2.0) and lower thresholds for detecting hypoglycemia (50.0 vs. 65.0 mg/dl) than patients without hypoglycemia problems. During the blinded CGM phase patients with hypoglycemic problems had a signifi cant longer duration of low glucose phases 248 vs. 153 minutes per day (p=.037; <70 mg/dl) respectively 173 vs. 96 minutes per day (p=.041; <60 mg/dl). Area under the receiver operating curve (ROC 0.72 p=.03) indicated a suffi cient screening performance of the duration of low glucose periods (< 70 mg/dl) for the identifi cation of patients with hypoglycemia problems. A cut-off of 170 minutes per day of time spend in the low glucose range had a sensitivity of 75% and a specifi city of 70.3%; the positive predictive value was 52.9%, the negative predictive value was 86.4%. A comparison of blind vs. open CGM showed that time spend in a low glucose range could be signifi cantly more reduced in patients with hypoglycemia problems than in patients without hypoglycemia problems during CGM open (< 60 mg/dl; - 67.8 min per day p=.040; < 50 mg/dl; -50.6 min per day, p=.038; < 40 mg/dl; -41.4 min. per day, p=.03). This study shows that CGM has an unused potential for identifying type 1 diabetic patients at risk for hypoglycemia problems in clinical practice as well as for avoidance of biochemical hypoglycemia, which plays a pivotal role for the development of hypoglycemia associated autonomic failure