Phase 3, Double Blinded, Placebo Controlled Study of the Effects of 12 Weeks DPP-IV Inhibitor Treatment on Secretion and Action of the Incretin Hormones in Patients With Type 2 Diabetes

Background The incretin effect, primarily mediated by the peptide hormones GIP and GLP-1, is known to be impaired in patients with type 2 diabetes, and characterised by reduced GLP-1 secretion and potency and a lack of responsiveness to the insulinotropic effect of GIP. The cause of this defect remains unknown, but exogenous administration of GLP-1 has shown promising results in attempts to restore the incretin effect. Due to rapid degradation of both incretin hormones by the enzyme dipeptidyl-peptidase IV (DPP-IV), treatment strategies now focus on GLP-1 analogues and prevention of hormone degradation through DPP-IV inhibition.

Hypothesis We hypothesize that that a gradual improvement in metabolic control induced by DPP-IV inhibitor (Januvia®) treatment significantly ameliorates the impaired secretion and potency of GLP-1 and leads to a restoration of the lost action of GIP.

Objective To assess the effect of three months treatment with Januvia®, administered as tablets once daily, on metabolic control in metformin treated patients with type 2 diabetes, measured as increases in incretin hormones and insulin secretion.

Efficacy end points Primary efficacy end point in trial part one is the relative increase in meal-induced total GLP-1 secretion after one and twelve weeks of Januvia® treatment.

Primary efficacy end point in part two is restoration of the insulinotropic effect of GIP, measured as the relative increase in GIP induced amplification of the late phase insulin secretion (AUC) response to glucose after 12 weeks of Januvia® treatment.