Safety \& tolerability were measured in terms of the # of participants with \>=1 adverse event (AE), \>=1 drug-related AE, \>=1 serious AE (SAE), or discontinued treatment due to an AE. SAEs included events occurring after initiation of glycemic rescue therapy. AE is defined as any unfavorable/unintended change in structure, function, or chemistry of the body temporally associated with the use of SPONSOR's product. SAE is defined as any AE that results in death, is life-threatening, an overdose, causes or prolongs in-patient hospitalization, or considered medically significant by the investigator.

Patients will be followed for 12 weeks with three meal test examinations; before treatment, after 1 week of treatment and after 12 weeks of treatment. Primary outcome is AUC GLP-1 (pM x 120 as stated).

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. Patients will be followed for 12 weeks with examinations after 1 and after 12 weeks of treatment.

Change from baseline at Week 24 is defined as Week 24 minus Week 0.

AUC (0-t) is the area under the curve for the plot showing plasma concentration against time from time zero to the time of the last quantifiable concentration for sitagliptin 50 mg, metformin 500 mg and metformin 850 mg.

Cmax is the peak serum concentration of a therapeutic drug after administration; and is used to determine the rate and extent of drug absorption. Cmax is reported for sitagliptin 50 mg, metformin 500 mg and metformin 850 mg.

Serum samples were used to determine the AUC from time 0 to infinity for sitagliptin. The placebo group is not included in the table below; this outcome measure only evaluated the sitagliptin groups.

The 24-hour WMG was calculated as the area under the 24-hour glucose curve (AUC(0-24 hr)) divided by 24 using linear trapezoidal method.