Reversible cognitive impairment after pioglitazone treatment of an elderly woman with type 2 diabetes mellitus and alzheimer's disease

A 81-year-old woman admitted for memory disturbance and type 2 diabetes mellitus was obese and hypertensive. Serum HbA1C was 8.7% and HOMA-R 5.08. Her standard score of mini mental state examination (MMSE) was 24 and 21 in Hasegawa's dementia scale-revised (HDS-R). She showed serious impairment in delayed recall, orientation, and executive function, and was diagnosed with probable Alzheimer's disease (AD) based on diagnostic criteria of the National Institute of Neurological and Communicative Disorders and Strokes-Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA). She was treated with metformin and glimepiride for diabetes and donepezil for AD, but her brain function declined to 19 in MMSE and 17 in HDS-R after 18 months. We added pioglitazone, and after 5 months, her HbAic fell to 6.3% and her HOMA-R to 2.89. Her brain dysfunction improved in several cognitive domains including short-term memory. Her MMSE score recovered to 24 and her HDS-R to 21, and she showed several improvements in daily performance. Pioglitazone thus appears to partially restore the cognitive AD decline in elderly diabetic patients.