Glycemic Effect and Safety of a Systemic, Partial Glucokinase Activator, PF-04937319, in Patients With Type 2 Diabetes Mellitus Inadequately Controlled on Metformin-A Randomized, Crossover, Active-Controlled Study

Glucokinase enhances glucose conversion to glucose-6-phosphate, causing glucose-stimulated insulin secretion from pancreatic cells and increased hepatic glucose uptake. PF-04937319 is a partial glucokinase activator designed to maintain efficacy with reduced hypoglycemia risk. In this randomized, double-blind, double-dummy, 3-period crossover phase 1b study, patients aged 18-70 years with type 2 diabetes mellitus and on metformin received once-daily PF-04937319 (300 mg), split-dose PF-04937319 (150+100 mg; breakfast+lunch), or sitagliptin (100 mg once daily). The primary end point was day 14 weighted mean daily glucose (WMDG) change from period-specific baseline. Secondary end points included change from baseline in fasting plasma glucose, premeal C-peptide and insulin, and safety, including hypoglycemia frequency. Mean decrease from baseline in observed WMDG (mg/dL) was greater for PF-04937319 (split-dose, -31.24; once daily, -31.33) versus sitagliptin (-19.24). Using the integrated glucose red-cell HbA(1c) model, the observed WMDG effect with both PF-04937319 dosing regimens was projected to yield a clinically superior effect on mean glycated hemoglobin (HbA(1c); split-dose, -0.88%; once daily, -0.94%) compared with sitagliptin (-0.63%). There was no difference in premeal C-peptide or insulin levels, and although the effect on WMDG with both PF-04937319 regimens was similar, the split-dose regimen appeared to offer some advantage in safety and tolerability.