In medical care for the elderly patients with diabetes mellitus, there are many cases that are not indicated for active treatment, because of their impairment of activity of daily living (ADL), instrumental ADL and cognitive function, and also the presence of some complications, such as cerebrovascular disorder. On the other hand, poor glycemic control is easy to induce dehydration, bacterial infection, and cognitive disorders in the elderly. Thus, it is necessary to maintain good glycemic control to preserve better ADL. However, compulsion of strict glycemic control might rather decrease QOL of the patient. To solve such a medical dilemma, the comprehensive geriatric assessment (CGA) is useful for the individual diabetic patient.