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Journal of Diabetes Research
Volume 2016, Article ID 4509603, 4 pages
Research Article

C-Peptide Levels Predict the Effectiveness of Dipeptidyl Peptidase-4 Inhibitor Therapy

1Department of Family Medicine, Eleskirt Public Hospital, 04600 Agri, Turkey
2Department of Endocrinology and Metabolic Diseases, Kartal Dr. Lutfi Kirdar Training and Research Hospital, 34890 Istanbul, Turkey
3Department of Family Medicine, Medeniyet University Goztepe Training and Research Hospital, 34722 Istanbul, Turkey

Received 12 September 2016; Accepted 13 October 2016

Academic Editor: Bernard Portha

Copyright © 2016 Sevin Demir et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background. Our aim was to define the conditions that affect therapeutic success when dipeptidyl peptidase-4 (DPP-4) inhibitor is added to metformin monotherapy. Materials and Methods. We reviewed the medical records of 56 patients who had received DPP-4 inhibitor as an add-on to metformin monotherapy and evaluated their response in the first year of therapy. Fasting blood glucose (FBG), HbA1c, C-peptide, and weight of the patients were recorded at 3-month intervals during the first year of treatment. Results. Patients who added DPP-4 inhibitor to metformin monotherapy had significant weight loss () and FBG and HbA1c levels were significantly lowered during the first 6 months (both ). Baseline levels of C-peptide were predictive for success of the treatment (), even after correction for confounding factors, for example, age, gender, or BMI (). Duration of diabetes was not a predictor of response to treatment (). Conclusion. Our study demonstrates that in patients having inadequate glycemic control, the addition of a DPP-4 inhibitor as a second oral agent to metformin monotherapy provides better glycemic control, protects β-cell reserves, and does not cause weight gain. These effects depend on baseline C-peptide levels.