OBJECTIVE: To evaluate the association between cognitive dysfunction and other barriers and glycemic control in older adults with diabetes. RESEARCH DESIGN AND METHODS: Patients over the age of 70 years presenting to a geriatric diabetes clinic were evaluated for barriers to successful diabetes management. Patients were screened for cognitive dysfunction with the Mini Mental State Examination (MMSE) and a clock-drawing test (CDT) scored by 1) a method validated by Mendez et al. and 2) a modified CDT (clock in a box [CIB]). Depression was evaluated with the Geriatric Depression Scale. Interview questionnaires surveyed activities of daily living (ADLs) and instrumental ADLs (IADLs), as well as other functional disabilities. RESULTS: Sixty patients (age 79 +/- 5 years, diabetes duration 14 +/- 13 years) were evaluated. Thirty-four percent of patients had low CIB (< or =5), and 38% of patients had low CDT (< or =13). Both CIB as well as CDT were inversely correlated with HbA(1c), suggesting that cognitive dysfunction is associated with poor glycemic control (r = -0.37, P < 0.004 and r = -0.38, P < 0.004, respectively). Thirty-three percent of patients had depressive symptoms with greater difficulty completing the tasks of the IADL survey (5.7 +/- 1.7 vs. 4.6 +/- 2.0; P < 0.03). These older adults with diabetes had a high incidence of functional disabilities, including hearing impairment (48%), vision impairment (53%), history of recent falls (33%), fear of falls (44%), and difficulty performing IADLs (39%). CONCLUSIONS: Older adults with diabetes have a high risk of undiagnosed cognitive dysfunction, depression, and functional disabilities. Cognitive dysfunction in this population is associated with poor diabetes control.