Deintensification of diabetic therapy is often clinically appropriate for older adults, because the benefit of aggressive diabetes treatment declines with age, while the risks increase.We examined rates of overtreatment and deintensification of therapy for older adults with diabetes, and whether these rates differed by medical, demographic, and socioeconomic characteristics.We analyzed Medicare claims data from 10 states, linked to outpatient laboratory values to identify patients potentially overtreated for diabetes (HbA1c < 6.5% with fills for any diabetes medications beyond metformin, 1/1/2011-6/30/2011). We examined characteristics associated with deintensification for potentially overtreated diabetic patients. We used multinomial logistic regression to examine whether patient characteristics associated with overtreatment of diabetes differed from those associated with undertreatment (i.e. HbA1c > 9.0%).Of 78,792 Medicare recipients with diabetes, 8560 (10.9%) were potentially overtreated. Overtreatment of diabetes was more common among those who were over 75 years of age and enrolled in Medicaid (p < 0.001), and was less common among Hispanics (p = 0.009). Therapy was deintensified for 14% of overtreated diabetics. Appropriate deintensification of diabetic therapy was more common for patients with six or more chronic conditions, more outpatient visits, or living in urban areas; deintensification was less common for those over age 75. Only 6.9% of Medicare recipients with diabetes were potentially undertreated. Variables associated with overtreatment of diabetes differed from those associated with undertreatment.Medicare recipients are more frequently overtreated than undertreated for diabetes. Medicare recipients who are overtreated for diabetes rarely have their regimens deintensified.