Effectiveness of GLP-1RA according to different type 2 diabetes phenotypes: A retrospective study

Aims: Type 2 diabetes (T2D) is a heterogeneous disease, with varying pathogenetic mechanisms influencing treatment response. Glucagon-like peptide-1 receptor agonists (GLP-1RA) offer clear metabolic benefits in T2D, but interindividual variability in response is observed. This retrospective study investigated whether GLP-1RA effectiveness varies by T2D phenotypes (severe insulin-deficient diabetes [SIDD], severe insulin-resistant diabetes [SIRD], mild obesity-related diabetes [MOD], mild age-related diabetes [MARD]) and assessed predictors of HbA1c reduction. Materials and Methods: Individuals attending the Endocrinology Unit at the University Hospital Policlinico Consorziale in Bari, Italy, between 01 January 2014, and 31 August 2024, were evaluated for participation. T2D phenotypes were assigned using the algorithm by Bello-Chavolla. The primary outcome was the difference in HbA1c change from baseline among phenotypes, and predictors were identified using SHAP and multivariable regression. Time to treatment failure (HbA1c >7.0%) was estimated with Kaplan–Meier analysis. Results: Among 181 patients, SIDD individuals yielded a significantly greater HbA1c reduction (−2.6%[1.9]) versus other phenotypes (p < 0.0001). Baseline HbA1c was the strongest predictor of HbA1c reduction. SIDD was linked to faster treatment failure (HR 3.69, 95% CI 1.37–9.94;p < 0.01), but this effect disappeared after adjustment for baseline HbA1c. Conclusion: This study adds to the emerging evidence against the hard clustering approach to T2D phenotyping in terms of response to treatment and time to treatment failure, particularly with GLP-1RA.