Telephone reminder systems have been used to assist in the treatment of many chronic diseases. However, it is unclear if these systems can increase medication and appointment adherence in patients with diabetes without direct patient–provider telephone contact. We tested the feasibility of using an automated telephone reminder system (ATRS) to deliver reminder messages to 253 adults with diabetes enrolled in a randomized controlled trial. Eighty-four percent of the patients were able to register using voice recognition and at least one reminder was delivered to 95% of registered patients over a period of 7.5 months. None of the demographic features studied predicted a patient's ability to enrol or to receive reminder calls. At the end of the study, 63% of patients indicated that they wished to continue to receive ATRS calls. The level of system use as determined by the number of received reminder calls was not associated with a change in the number of physician visits or diabetes-related laboratory tests during follow-up. The clinical benefits and sustainability of ATRS remain unproven, but our results indicate that an automated reminder system can be effective for providing messages to a large group of older patients with diabetes.