Efficacy of Sitagliptin Plus Metformin for Type 2 Patients

In this 52-week treatment study, 150 patients (mean age, 54.9 ± 12.5 years) with type 2 diabetes and HbA1c of 7.0-10% were treated with sitagliptin 100 mg once and metformin 500 mg twice daily.

To assess the predictive parameters for therapeutic efficacy, a multivariate regression analysis was performed with baseline fasting glucose, insulin, C-peptide, and glucagon levels, homoeostasis model assessment-insulin resistance (HOMA-IR) and beta-cell function (HOMA-B), insulinogenic index (IGI, defined as 30-0 min insulin/30-0 min glucose), and area under the curve for glucose, insulin, and C-peptide obtained after 75-g oral glucose tolerance test.

The results showed that after 52 weeks, mean HbA1c levels and fasting and postload 2-h glucose were significantly decreased from 8.7 ± 1.4% to 7.2 ± 1.3%, 9.2 ± 3.0 to 7.2 ± 1.8 mm, and 17.5 ± 5.1 to 10.9 ± 3.6 mm, respectively (P < 0.01).

HOMA-B and IGI increased significantly from 50.3 ± 33.5 to 75.1 ± 32.8 and from 11.3 ± 1.3 to 35.0 ± 6.3 at 52 weeks, respectively (P < 0.01).

Multivariate regression analysis indicated that the reduction in HbA1c was significantly associated with high baseline HbA1c, low IGI, and short duration of diabetes after adjusting for age, sex, body mass index, blood pressure, triglycerides, creatinine, high-sensitivity CRP, glucagon, C-peptide, HOMA-B, and HOMA-IR. And no severe adverse events were observed.

Clinical Endocrinology, 07/18/2012