Diabetes mellitus is a public health concern, affecting 10.5% of the population. Protocatechuic acid (PCA), a polyphenol, exerts beneficial effects on insulin resistance and diabetes. This study investigated the role of PCA in improving insulin resistance and the crosstalk between muscle with liver and adipose tissue. C2C12 myotubes received four treatments: Control, PCA, insulin resistance (IR), and IR-PCA. Conditioned media from C2C12 was used to incubate HepG2 and 3T3-L1 adipocytes. The impact of PCA was analyzed on glucose uptake and signaling pathways. PCA (80 µM) significantly enhanced glucose uptake in C2C12, HepG2, and 3T3-L1 adipocytes (p < 0.05). In C2C12, PCA significantly elevated GLUT-4, IRS-1, IRS-2, PPAR-γ, P-AMPK, and P-Akt vs. Control (p ≤ 0.05), and modulated pathways in IR-PCA. In HepG2, PPAR-γ and P-Akt increased significantly in Control (CM) vs. No CM, and PCA dose upregulated PPAR-γ, P-AMPK, and P-AKT (p < 0.05). In the 3T3-L1 adipocytes, PI3K and GLUT-4 expression was elevated in PCA (CM) vs. No CM. A significant elevation of IRS-1, GLUT-4, and P-AMPK was observed in IR-PCA vs. IR (p ≤ 0.001). Herein, PCA strengthens insulin signaling by activating key proteins of that pathway and regulating glucose uptake. Further, conditioned media modulated crosstalk between muscle with liver and adipose tissue, thus regulating glucose metabolism.

Gliclazide was approved as a treatment for type 2 diabetes in an era before model-based drug development, and consequently, the recommended doses were not optimised with modern methods. To investigate various dosing regimens of gliclazide, we used publicly available data to characterise the doseresponse relationship using pharmacometric models. A literature search identified 21 published gliclazide pharmacokinetic (PK) studies with full profiles. These were digitised, and a PK model was developed for immediate-(IR) and modified-release (MR) formulations. Data from a gliclazide dose-ranging study of postprandial glucose were used to characterise the concentration-response relationship using the integrated glucose-insulin model. Simulations from the full model showed that the maximum effect was 44% of the patients achieving HbA1c <7%, with 11% experiencing glucose <3 mmol/L and the most sensitive patients (i.e., 5% most extreme) experiencing 35 min of hypoglycaemia. Simulations revealed that the recommended IR dose (320 mg) was appropriate with no efficacy gain with increased dose. However, the recommended dose for the MR formulation may be increased to 270 mg, with more patients achieving HbA1c goals (i.e., HbA1c <7%) without a hypoglycaemic risk higher than the resulting risk from the recommended IR dose.