Initial therapy with the fixed‐dose combination of sitagliptin and metformin results in greater improvement in glycaemic control compared with pioglitazone monotherapy in patients with type 2 diabetes
Authors: Wainstein J. , Katz L. , Engel S. S. , Xu L. , Golm G. T. , Hussain S. , O’Neill E. A. , Kaufman K. D. , Goldstein B. J. 
Published: November 2011

Aims: To evaluate the efficacy and safety of initial therapy with a fixed‐dose combination (FDC) of sitagliptin and metformin compared with pioglitazone in drug‐naÏve patients with type 2 diabetes.

Methods: After a 2‐week single‐blind placebo run‐in period, patients with type 2 diabetes, HbA1c of 7.5–12% and not on antihyperglycaemic agent therapy were randomized in a double‐blind manner to initial treatment with a FDC of sitagliptin/metformin 50/500 mg twice daily (N = 261) or pioglitazone 30 mg per day (N = 256). Sitagliptin/metformin and pioglitazone were up‐titrated over 4 weeks to doses of 50/1000 mg twice daily and 45 mg per day, respectively. Both treatments were then continued for an additional 28 weeks.

Results: From a mean baseline HbA1c of 8.9% in both groups, least squares (LS) mean changes in HbA1c at week 32 were −1.9 and −1.4% for sitagliptin/metformin and pioglitazone, respectively (between‐group difference = −0.5%; p < 0.001). A greater proportion of patients had an HbA1c of <7% at week 32 with sitagliptin/metformin vs. pioglitazone (57% vs. 43%, p < 0.001). Compared with pioglitazone, sitagliptin/metformin treatment resulted in greater LS mean reductions in fasting plasma glucose (FPG) [−56.0 mg/dl (−3.11 mmol/l) vs. −44.0 mg/dl (−2.45 mmol/l), p < 0.001] and in 2‐h post‐meal glucose [−102.2 mg/dl (−5.68 mmol/l) vs. −82.0 mg/dl (−4.56 mmol/l), p < 0.001] at week 32. A substantially greater reduction in FPG [−40.5 mg/dl (−2.25 mmol/l) vs. −13.0 mg/dl (−0.72 mmol/l), p < 0.001] was observed at week 1 with sitagliptin/metformin vs. pioglitazone. A greater reduction in the fasting proinsulin/insulin ratio and a greater increase in homeostasis model assessment of β‐cell function (HOMA‐β) were observed with sitagliptin/metformin than with pioglitazone, while greater decreases in fasting insulin and HOMA of insulin resistance (HOMA‐IR), and a greater increase in quantitative insulin sensitivity check index (QUICKI) were observed with pioglitazone than with sitagliptin/metformin. Both sitagliptin/metformin and pioglitazone were generally well tolerated. Sitagliptin/metformin led to weight loss (−1.4 kg), while pioglitazone led to weight gain (3.0 kg) (p < 0.001 for the between‐group difference). Higher incidences of diarrhoea (15.3% vs. 4.3%, p < 0.001), nausea (4.6% vs. 1.2%, p = 0.02) and vomiting (1.9% vs. 0.0%, p = 0.026), and a lower incidence of oedema (1.1% vs. 7.0%, p < 0.001), were observed with sitagliptin/metformin vs. pioglitazone. The between‐group difference in the incidence of hypoglycaemia did not reach statistical significance (8.4 and 4.3% with sitagliptin/metformin and pioglitazone, respectively; p = 0.055).

Conclusion: Compared with pioglitazone, initial therapy with a FDC of sitagliptin and metformin led to significantly greater improvement in glycaemic control as well as a higher incidence of prespecified gastrointestinal adverse events, a lower incidence of oedema and weight loss vs. weight gain.