Diabetic individuals without other primary causes of cognitive impairment (brain tumor, previous neurosurgery, medications impairing memory) and able to swallow without difficulty will undergo pulsatile insulin treatments weekly over a period of 6-12 months with renewals for successive six month periods. Serial cognitive studies using Mindstream testing, Wechsler Memory Scale II and other localizing cognitive function tests will be done before the start of of treatment and every 3 months thereafter.This study began in 2002 and is continuing.