Although nearly one-third of older diabetics are cognitively impaired, their diabetes management remains poorly understood. To examine the relationship between cognitive impairment and diabetes self-management in a population-based community sample of older adults with Type 2 diabetes. Cross-sectional observational analysis. 1,398 persons with diabetes, aged 60 years or older, who responded to the 2003 Health and Retirement Study Diabetes Survey. We conducted logistic regressions on the effects of cognitive impairment on respondents' self-management ability after controlling for diabetes comorbidities, demographics, and clinical characteristics. Participants with greater cognitive impairment were less likely to adhere to exercise (Adjusted Odds ratio [AOR] = 0.725 and 0.712 for moderate and severe cognitive impairment, both P < 0.05), and to diet (AOR = 0.906 and 0.618 for moderate and severe cognitive impairment, both P < 0.01). Cognitive impairment is associated with worse self-care and may pose challenges to diabetic older persons, notably in diet and exercise. Cognitive screening may be indicated in this high risk group.