Diet is an important component of the management of Insulin Dependent Diabetes Mellitus (IDDM), yet it has been difficult to obtain effective measures of dietary management. Two studies were conducted assessing the frequency and antecedents of problems in dietary self-care in IDDM. In study one the Diet Problem Setting Inventory (DPSI), a self-report inventor assessing the settings in which poor dietary management occur, was developed. One hundred and thirty-seven individuals with IDDM completed the DPSI, and a factor analysis revealed three internally consistent factors. In study two, 41, IDDM patients self-monitored, and were interviewed daily about their diet, to ascertain the frequency and antecedents of problems in dietary self-care. Subjects also completed the DPSI twice to assess its test-retest reliability. The total score on the DPSI showed high test-retest reliability, and moderate convergent validity with self-monitored dietary management. The more intensive self-monitoring assessment provided greater information on the settings in which poor dietary management occurred. It was concluded that global self-report inventories, such as the DPSI, have value as screening instruments, but that self-monitoring provides additional information of clinical utility.