Endocrine Abstracts

Objective: To evaluate the GRI and its association with other CGM metrics after initiation of automated insulin delivery (AID) system in adults with type 1 diabetes (awT1D).

Methods: Up to 90 days of CGM data before and after initiation of an AID system from 185 awT1D were collected. GRI with hypoglycemia and hyperglycemia components and other CGM metrics were calculated using cgmanalysis R software and analyzed for 24-hour, nighttime, and daytime. GRI values were assigned to 5 GRI zones as zone A (0-20), zone B (21-40), zone C (41-60), zone D (61-80), zone E (81-100).

Results: After AID initiation, GRI, its two components and other CGM metrics improved significantly (Table-1). The percentage of people in each zone changed as follows: A: 10.8% to 24.7%; B: 23.8% to 58.4%; C: 36.2% to 15.1%, D: 20.5% to 0.5%, and E: 8.7% to 0%. GRI was correlated with time between 181-250 mg/dl before (r=0.691, P<0.001) and after (r=0.818, P<0.001) and time above 250 mg/dl before (r=0.925, P<0.001) and after (r=0.920, P<0.001). GRI was not correlated with time between 54-70 mg/dl before (r=-0.029, P=0.698) and after (r=0.038, P=0.611), and with time below 54 mg/dl before (r=0.123, P=0.096) and after (r=0.140, P=0.058). Improvement in nighttime, compared to daytime, was superior; as seen in increased TIR and decreased GRI (P<0.001 for both). GRI improved by 19.7 percentiles and TIR improved by 14.6 percent.

Conclusion: GRI was highly correlated with various CGM metrics above (but not below) target range, both before and after AID initiation. Improvement in GRI was greater than improvement in TIR, and both were significant, GRI, compared to TIR, was a better indicator for improved glycemia after AID initiation.