Limitations of the HOMA-B Score for Assessment of β-Cell Functionality in Interventional Trials—Results from the PIOglim study

Abstract Background: Drugs with unspecific stimulating effects on β-cell secretion increase the homeostasis model assessment (HOMA)-B score, indicating improved β-cell “function.” We investigated whether the β-cell protection provided by adding pioglitazone (PIO) to glimepiride (GLIM) in comparison to up-titrating the GLIM dose alone is reflected by appropriate changes in several measures of β-cell function, including HOMA-B score. Methods: This double-blind, parallel prospective 6-month study was performed with 82 patients (47 men, 35 women; age, 61 ± 9 years; duration of disease, 5.3 ± 4.4 years; body mass index, 32.6 ± 6.0 kg/m2; hemoglobin A1c [HbA1c], 7.3 ± 0.7%) with GLIM monotherapy (1–3 mg). They were randomized to receive a GLIM + PIO combination with up-titration (2 mg + 30 mg/4 mg + 30 mg/4 mg + 4 mg) or to remain on GLIM (up-titration 4/5/6mg). Observation parameters determined at baseline and end point included HOMA-B, HOMA-IR, HbA1c, glucose, insulin, and intact proinsulin. Results: There wa...