Glycolsylated hemoglobin (G Hb) levels and data on adherence and patient-provider discordance in beliefs about diabetes were collected from 42 insulin-requiring patients with diabetes. Discordance was calculated for both degree of discordance (absolute amount of disagreement) and direction of discordance (degree to which physician > patient or patient < physician). Patients generally agreed with physicians in perceptions of severity, costs of adherence, and immediate and long-term benefits of adherence. Significant differences were found between these dimensions. Only discordance on long-term benefits of adherence correlated with adherence, with greater discordance related to greater adherence. Discordance on the cost dimension correlated negatively with G Hb, suggesting better glycemic control with greater disagreement. Those who underestimate the cost of adherence show greater adherence. Adherence did not correlate significantly with glycemic control.