Type 2 diabetes results when the body does not produce enough insulin to regulate blood sugar. This study is designed to measure the effect of vildagliptin on the maximum insulin secretion by the pancreas.

Inclusion Criteria:

• Diagnosed with type 2 diabetes for at least 6 months
• Patients whose diabetes is controlled by diet and exercise only or patients taking metformin
• BMI in the range 22-45
• Blood glucose criteria must be met

Exclusion Criteria:

• Pregnancy or lactation
• Type 1 diabetes or diabetes resulting from pancreatic injury
• Cardiovascular complications as defined by the protocol
• Significant diabetic complications as defined by the protocol

Other protocol-defined inclusion/exclusion criteria may apply