The primary purpose of this study is to determine whether the use of a computer assisted decision support (CADS)system by primary care providers (PCPs) for their patients with type 2 diabetes mellitus (T2DM) changes the quality of care relative to a "usual care" group in terms of objective outcome measures of glycemic control (e.g., A1C, mean blood glucose, frequency of hypoglycemic episodes) and in terms of subjective ratings by patients.