Diabetes is associated with increased rate of cognitive decline in questionably demented elderly.

BACKGROUND This study examines whether the association of diabetes with the rate of cognitive decline varies according to dementia severity. METHODS Longitudinal study on subjects residing in nursing homes and assisted living (n = 342). The Mini Mental State Examination (MMSE) was used to measure the rate of cognitive decline in diabetic and nondiabetic subjects who were nondemented (Clinical Dementia Rating, CDR = 0; n = 125), questionably demented (CDR = 0.5; n = 58) or frankly demented (CDR > or =1; n = 89) at baseline. Diagnosis of diabetes was ascertained by review of medical records and history. RESULTS Diabetes was associated with an increased rate of decline in the MMSE score of questionably demented subjects (p < 0.0001). In frankly demented subjects, diabetes tended to be associated with less cognitive decline (p = 0.04). Diabetes was not associated with the rate of MMSE decline in nondemented subjects (p = 0.89). CONCLUSION In individuals with questionable dementia (CDR = 0.5), diabetes is associated with a faster rate of cognitive decline as measured by the MMSE, but not in nondemented (CDR = 0) or frankly demented (CDR > or =1) individuals.