incidence of hypoglycaemia in patients treated with sitagliptin was similar to placebo. Body weight did not increase from baseline with sitagliptin therapy. Improvements in surrogate markers of beta cell function, including HOMA-β (Homeostasis Model Assessment-β), proinsulin to insulin ratio, and measures of beta cell responsiveness from the frequently-sampled meal tolerance test were observed.
Studies of sitagliptin in combination with metformin
In a 24-week, placebo-controlled clinical study to eva luate the efficacy and safety of the addition of sitagliptin 100 mg once daily to ongoing metformin, sitagliptin provided significant improvements in glycaemic parameters compared with placebo. Change from baseline in body weight was similar for patients treated with sitagliptin relative to placebo. In this study there was a similar incidence of hypoglycaemia reported for patients treated with sitagliptin or placebo.
In a 24-week placebo-controlled factorial study of initial therapy, sitagliptin 50 mg twice daily in combination with metformin (500 mg or 1,000 mg twice daily) provided significant improvements in glycaemic parameters compared with either monotherapy. The decrease in body weight with the combination of sitagliptin and metformin was similar to that observed with metformin alone or placebo; there was no change from baseline for patients on sitagliptin alone. The incidence of hypoglycaemia was similar across treatment groups.
Study of sitagliptin in combination with metformin and a sulphonylurea
A 24-week placebo-controlled study was designed to eva luate the efficacy and safety of sitagliptin (100 mg once daily) added to glimepiride (alone or in combination with metformin). The addition of sitagliptin to glimepiride and metformin provided significant improvements in glycaemic parameters. Patients treated with sitagliptin had a modest increase in body weight (+1.1 kg) compared to those given placebo.
Study of sitagliptin in combination with metformin and a PPARγ agonist
A 54 week placebo-controlled study was designed to eva luate the efficacy and safety of sitagliptin (100 mg once daily) added to the combination of rosiglitazone and metformin. The addition of sitagliptin to rosiglitazone and metformin provided significant improvements in glycaemic parameters at the primary timepoint of Week 18, with improvements sustained through the end of the study. Change from baseline in body weight was similar for patients treated with sitagliptin relative to placebo (1.9 vs. 1.3 kg).
Study of sitagliptin in combination with metformin and insulin
A 24-week placebo-controlled study was designed to eva luate the efficacy and safety of sitagliptin (100 mg once daily) added to insulin (at a stable dose for at least 10 weeks) with or without metformin (at least 1,500 mg). In patients taking pre-mixed insulin, the mean daily dose was 70.9 U/day. In patients taking non-pre-mixed (intermediate/long-acting) insulin, the mean daily dose was 44.3 U/day. Data from the 73 % of patients who were taking metformin are presented in Table 3. The addition of sitagliptin to insulin provided significant improvements in glycaemic parameters. There was no meaningful change from baseline in body weight in either group.
Table 3: HbA1c results in placebo-controlled combination therapy studies of sitagliptin and metformin*
Study
Mean baseline HbA1c (%)
Mean change