The objective of this study was to evaluate the value of an intensive telephone follow-up as an additional component of a diabetes disease management program already shown to be effective in improving glycemic control, adherence with American Diabetes Association (ADA) standards of care, and health-related quality of life (HRQOL). The study involved a randomized controlled trial. The intervention group received a series of 12 weekly phone calls reinforcing base education and self-management skills. Five hundred and seven consenting patients, age 18 years or older, with type 1 or type 2 diabetes mellitus referred to the hospital- based disease management program who had telephones and were able to complete surveys in English or Spanish were enrolled. Outcomes were evaluated at 3 and 12 months follow- up. Adherence to ADA standards of care, specifically annual eye exams, physician foot exams, foot self-exams, and pneumonia vaccination were significantly better with the added telephone intervention, but there were no differences between the groups on glycemic control, HRQOL, or patient satisfaction. The effectiveness of the disease management program was replicated with sustained improvement in glycemic control, HRQOL, and adherence to ADA standards. The additional telephone intervention further improved adherence to ADA guidelines for self-care and medical care but did not affect glycemic control or HRQOL.