Impact of continuous glucose monitoring on glycaemic risk index in adults with type 1 diabetes using multiple daily insulin injections in the GOLD trial

Background: Continuous glucose monitoring (CGM) has significantly improved glycaemic management in individuals with diabetes. The Glycaemia Risk Index (GRI) is a composite metric based on CGM data that provides a comprehensive evaluation of glycaemic quality, incorporating both hypoglycaemia and hyperglycaemia. This study evaluated the impact of transitioning from self-monitoring of blood glucose (SMBG) to CGM on GRI in adults with type 1 diabetes (T1D) using multiple daily injection (MDI) insulin therapy. Methods: Secondary analyses were conducted in 125 adults with T1D from the randomised GOLD trial. Participants alternated between CGM and SMBG for two 26-week periods, separated by a 17-week wash-out. The GRI was calculated on a 0-100 scale from CGM data and categorised into five risk zones. Associations between baseline characteristics and participant-reported outcomes such as diabetes-related behaviours, lifestyle, psychological characteristics, and changes in GRI were also explored. Results: = -0.47, 95% CI -0.60, -0.32), but standardised effect sizes were larger for GRI than for TIR (-0.5 [95% CI -0.72, -0.34] vs. 0.2 [95% CI 0.00, 0.37]). Exploratory analyses suggested that self-reported psychosocial traits influenced GRI changes: thoroughness was linked to greater reductions in hypoglycaemia risk, whereas distractibility, self-described laziness, and carbohydrate counting training were associated with smaller improvements. Conclusion: Switching from SMBG to CGM significantly improved GRI in adults with T1D on MDI therapy. Compared with TIR, GRI demonstrated greater responsiveness to treatment-related changes. As a composite metric that integrates both hypo- and hyperglycaemia, GRI may serve as a valuable endpoint for evaluating interventions and as a complementary measure in clinical practice.