Use of the Glycemia Risk Index at Hybrid Closed-Loop Initiation to Predict Combined International Glucose Targets at 12 Months: Results From the CIRDIA Study Group.

Background: Hybrid closed-loop (HCL) therapy helps reaching efficacy and safety glucose targets (ESGT+) in persons with type 1 diabetes (PwT1D). We analyzed here the glycemia risk index (GRI) in PwT1D at HCL initiation (M₀) and at 12 months (M₁₂) and determined whether M₀GRI value and/or M₀GRI zone (A-B-C-D-E) could identify people reaching M₁₂ESGT+.

Methods: This was a retrospective study. Consecutive PwT1D who started HCL in a CIRDIA center were included after written consent. Glucose parameters were manually extracted from platforms at M₀ and M₁₂. ESGT+ meant reaching time in range (TIR) > 70% and glucose management indicator < 7% and time below range (TBR)^<70 < 4% and TBR^<54< 1%. Glycemia risk index was calculated and receiver-operating characteristic (ROC) analyses were performed to study the relation between M₀GRI and M₁₂ESGT+/M₁₂ESGT-.

Results: M₁₂ data were available for 128 PwT1D. M₀GRI predicted M₁₂ESGT mostly for low and high M₀GRI values. An M₀GRI < 41 had a 90% specificity, a 36% sensitivity, and a 74% positive predictive value for M₁₂ESGT+. Sensitivity increased to 80% but specificity dropped to 56% for M₀GRI < 61 and M₀GRI ≥ 61 had a 78% negative predictive value. All PwT1D with M₀GRI 0 to 20 (zone A) reached M₁₂ESGT+. Then, the percentage of M₁₂ESGT+ people dropped about 25% per M₀GRI zone (A-B-C-D) and to 11% for zone E.

Conclusions: M₀GRI was significantly associated with M₁₂ESGT status but mostly when in zones A-B or D-E. Hybrid closed-loop training should focus on PwT1D with M₀GRI ≥ 41 (90% of M₁₂ESGT- persons), but reaching M₁₂ESGT+ is possible with M₀GRI in zones C-D-E (64% of M₁₂ESGT+ persons) and even D-E (20% of M₁₂ESGT+ persons).