Impact of Tirzepatide on FIB-4 in Patients with Type 2 Diabetes: A Comparison between GLP-1RA-naïve and GLP-1RA Switch Initiation in a Retrospective Cohort.

Objective Tirzepatide, a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist, has been shown to improve hepatic inflammation and steatosis in patients with type 2 diabetes. However, whether its effects on Fibrosis-4 (FIB-4), a surrogate marker of liver fibrosis, differ between patients naїve to GLP-1 receptor agonists (GLP-1RAs) and those who have switched from a GLP-1RA remains unclear. Methods In this single-center retrospective study, 65 Japanese patients with type 2 diabetes received tirzepatide for ≥6 months (GLP-1RA-naïve: n=15; GLP-1RA-treated: n=50). The primary outcome was change in the FIB-4. The secondary endpoints included changes in glycated hemoglobin (HbA1c), body weight, urinary protein, and estimated glomerular filtration rate (eGFR). Multivariable analyses were performed to identify the predictors of FIB-4 improvement. Results FIB-4 significantly decreased in the GLP-1RA-naïve group (from 1.55±1.01 to 1.25±0.74, Δ-0.26±0.32, p<0.01) but not in the GLP-1RA-treated group (Δ-0.02±0.23), with a significant between-group difference (p<0.05). HbA1c decreased in both groups, with a greater reduction in GLP-1RA-naïve patients (Δ-2.0±1.3% vs. -1.0±1.3%, p<0.01). Body weight decreased significantly in both groups (-3.5±5.5 kg vs. -2.2±3.5 kg), with no between-group difference. A multivariable analysis identified age, baseline FIB-4, and GLP-1RA-naïve status as independent predictors of FIB-4 reduction. Conclusion Tirzepatide significantly reduced FIB-4, particularly in patients who were GLP-1RA-naïve, and produced substantial reductions in HbA1c and body weight. As an exploratory and hypothesis-generating analysis, these findings suggest that initiating tirzepatide in GLP-1RA-naïve patients may be associated with favorable changes in fibrosis-related risk markers in patients with type 2 diabetes at a high risk of liver fibrosis.