Comparative Effects of SGLT2 Inhibitors and GLP-1 Receptor Agonists on Composite Surrogate Markers of Insulin Resistance: A Real-World Study Using METS-IR and SPISE

Objective: Insulin resistance is a key pathophysiological driver linking obesity and type 2 diabetes (T2D) with cardiovascular risk. Composite surrogate indices derived from routine clinical parameters, such as the Metabolic Score for Insulin Resistance (METS-IR) and the Single Point Insulin Sensitivity Estimator (SPISE), may provide a practical means of capturing multidimensional metabolic changes. Given that comparative data are limited, we aimed to evaluate the effects of sodium–glucose cotransporter-2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1RA) on these indices in individuals with T2D and overweight or obesity. Methods: In this retrospective observational study, 100 individuals with T2D treated with either GLP-1RA (n = 54) or SGLT2i (n = 46) were evaluated over 6 months. Strict inclusion criteria ensured treatment stability without initiation or modification of concomitant pharmacotherapy. Changes in METS-IR and SPISE were assessed alongside body mass index (BMI) and glycated hemoglobin (HbA1c). Multivariable regression and exploratory analyses, including stratification by BMI and correlation analyses, were performed. Results: Both treatment groups demonstrated significant improvements in METS-IR (GLP-1RA: −3.9 ± 5.9; SGLT2i: −2.5 ± 2.6; both p < 0.001) and SPISE (GLP-1RA: +0.46 ± 0.52; SGLT2i: +0.44 ± 0.61; both p < 0.001), with no significant between-group differences. In the GLP-1RA group, changes in METS-IR correlated with changes in BMI (r = 0.48, p < 0.001) and HbA1c (r = 0.29, p = 0.030), whereas no significant correlations were observed in the SGLT2i group. Stratified analyses indicated greater reductions in METS-IR among individuals with BMI ≥30 kg/m2 treated with GLP-1RA. Conclusions: Both SGLT2i and GLP-1RA improve composite surrogate markers of insulin resistance, with distinct associations with weight and glycemic changes. METS-IR and SPISE may serve as practical tools for monitoring multidimensional metabolic responses in clinical practice.