The purpose of this study is to explore long term glucose variability of a combination therapy of metformin and vildagliptin compared to a metformin - gliclazide combination.

Multicenter, randomized, open, parallel group, Phase IV study, of 18 months duration.

• Trial with medicinal product

Inclusion criteria:

1. Male or female patients aged =30 -= 75 years.
2. History of type 2 diabetes for at least 6 months.
3. Patients inadequately controlled (i.e. not reaching target) with maximum tolerated doses of metformin with HbA1c of 6.5-9.0%.
4. Patients inadequately controlled (i.e. not reaching target) with maximum tolerated doses of metformin with a body mass index (BMI) of 25-40 kg/m2.
5. Patients that are currently treated with metformin, gliclazide or both but not with other glucose lowering agents.
6. Outpatient.
7. If female of childbearing potential: Will to practice reliable birth control measures [e.g., surgical sterilization, hormonal contraception, double-barrier methods (any double combination of IUD, male or female condom with spermicidal gel, diaphragm, sponge, cervical cap)] during study treatment and for at least 28 days after completion of study medication; not lactating or pregnant; and has a documented negative pregnancy test result at baseline.

Exclusion criteria:

1. Type 1 diabetes as defined by the American Diabetes Association (ADA).

2. Type 2 diabetes currently (last 3 months) treated with insulin or glitazones.

3. Acute or chronic diseases causing tissue hypoxia such as:

   • cardiac or respiratory insufficiency
   • myocardial infarct within the last 6 months

4. Active liver disease with alanine aminotransferase (ALAT) and / or aspartate aminotransferase (ASAT) > 3 x upper limit of normal.

5. Relevant kidney disease such as :

   • serum creatinine =133 µmol/l in males and > 124 µmol/l in females
   • proteinuria > 300 mg/l
   • status post kidney transplantation
   • severe infection
   • intravascular administration of contrast medium containing iod within the last 7 days

6. Severe neuropathy (vibration perception at the base of the big toes <2/8).

7. Active proliferative diabetic retinopathy.

8. Any clinically relevant major organ system disease including mental illnesses

9. History of malignancy

10. Pancreatitis

11. Porphyria

12. Severe disturbances of the adrenal gland

13. Severe disturbances of the thyroid gland

14. Allergy to vildagliptin or one of the excipients

15. Allergy to metformin or one of the excipients

16. Allergy to gliclazide, sulfonylurea or sulfonamides or one of the excipients.

17. Drug or alcohol abuse.

18. Pregnant or nursing (lactating) women, where pregnancy is defined as the state of a female after conception and until the termination of gestation, confirmed by a positive pregnancy test (serum or urine).

19. Any other condition that could interfere with the participation in the study according to the study protocol or with the ability to cooperate and comply with the study procedures.

20. Treatment with any investigational drug, within 30 days or 5 half-lives before screening, whichever is longer.