CGM Metrics Identify Dysglycemic States in Subjects from the TrialNet Pathway to Prevention Study

   OBJECTIVE  Continuous glucose monitoring (CGM) parameters may identify subjects at risk of progressing to overt type 1 diabetes. We aimed to determine whether CGM metrics provides additional insights into progression to clinical Stage 3 type 1 diabetes.  RESEARCH DESIGN AND METHODS  One hundred and five relatives of type 1 diabetes probands (median age 16.8 years; 89% non-Hispanic White; 43.8% female) from the TrialNet Pathway to Prevention Study underwent 7-day CGM assessments and oral glucose tolerance tests (OGTTs) at 6-month intervals, the baseline data is reported here. Three groups were evaluated: individuals with 1) Stage 2 type 1 diabetes (n=42) with ≥2 diabetes-related autoantibodies and abnormal OGTT; 2) Stage 1 type 1 diabetes (n=53) with ≥2 diabetes-related autoantibodies and normal OGTT; and 3) negative test for all diabetes-related autoantibodies and normal OGTT (n=10).  RESULTS  Multiple CGM metrics were associated with progression to Stage 3 type 1 diabetes. Specifically, spending ≥5% time with glucose levels ≥140 mg/dL (p = 0.01), ≥8% time ≥140 mg/dL (p=0.02), ≥5% time ≥160 mg/dL (p = 0.0001) and ≥8% of the time spent at glucose levels ≥160 mg/dL (p=0.02) were all associated with progression to Stage 3 disease. Stage 2 participants and those who progressed to Stage 3 also exhibited higher mean day-glucose values, spent more time with glucose values over 120, 140 and 160 mg/dL, and had greater variability. CONCLUSIONS  CGM could aid in the identification of subjects, including those with a normal OGTT, who are likely to rapidly progress to Stage 3 type 1 diabetes. </p