Effects of DPP-4 Inhibition on Calcium and Bone Metabolism in Type 2 Diabetes Mellitus

Inclusion Criteria:

1. Type 2 diabetes mellitus.

2. Hemoglobin A1c >6.5% and <10%.

3. Estimated GFR greater than 60 mL per minute per meter squared.

4. Between 18 and 70 years of age.

5. On oral antihyperglycemic agents with stable dose at least for last 2 months.

6. Females: minimum of two years postmenopausal, surgically sterile, or using an
acceptable contraceptive regimen (OCP, IUD, double barrier, Depo-Provera or
subcutaneous progestin implant) and negative urine pregnancy test at trial start.

Exclusion Criteria:

1. Pregnancy, breast feeding or planning pregnancy during the study period

2. Any medical condition expected to be terminal within one year

3. Active mental illness or other condition which in the opinion of the investigator
would prevent informed consent or adherence with study protocol

4. Use of any PPAR agonist within three months prior to enrollment

5. Daily insulin use

6. Vitamin D level < 20

7. Allergy or intolerance of sitagliptin or other DPP-4 inhibitor

8. Use of DPP-4 inhibitor or GLP-1 analog within three months prior to enrollment

9. Significant alcohol use defined as >3 standard servings of alcohol per day for men
and >2 for women

10. History of bariatric surgery in the last 3 years or planned bariatric surgery during
the study period

11. Receipt of another study drug within 30 days of screening.