Many people with type 2 diabetes cannot maintain target blood glucose levels when taking a single oral drug. The purpose of this study is to assess the safety and effectiveness of vildagliptin, an unapproved drug, in lowering overall blood glucose levels when added to pioglitazone in people with type 2 diabetes not at target blood glucose levels on either pioglitazone or rosiglitazone alone.

Inclusion Criteria:

• Blood glucose criteria must be met
• Previously responded, as defined by the protocol, to treatment with pioglitazone or rosiglitazone
• Body mass index (BMI) in the range 22-45

Exclusion Criteria:

• Type 1 diabetes
• Pregnancy or lactation
• Evidence of serious cardiovascular complications
• Evidence of serious diabetic complications
• Laboratory value abnormalities as defined by the protocol
• Known sensitivity to pioglitazone
• Other protocol-defined exclusion criteria may apply