ObjectiveTo compare the limits of agreement between the SpaceLabs 90207 oscillometric blood pressure measurement device and the sphygmomanometer for patients with insulin-dependent diabetes mellitus (IDDM) versus healthy control subjects.DesignA retrospective analysis of six simultaneous blood pressure measurements in 106 IDDM patients aged 32.6 ± 12.0 years (mean ± SD) and 92 healthy control subjects aged 27.1 ± 8.9 years with the SpaceLabs device and a sphygmomanometer.ResultsFor both groups, overestimation of the systolic blood pressure occurred with the SpaceLabs device, being more severe for the IDDM group (1.7 mmHg more overestimation,P= 0.009). Mean arterial blood pressure was underestimated for the control group and overestimated for the IDDM group (2.7 mmHg underestimation and 0.8 mmHg overestimation, respectively). Diastolic blood pressures for both groups were underestimated by use of the SpaceLabs device, but less severely so for the IDDM group (4.2 mmHg,P< 0.0001 less underestimation). Multiple regression analysis revealed that these differences were mainly due to the presence of diabetes. Other determinants of these limits of agreement were age (for control group subjects) and duration of diabetes (for IDDM group patients).ConclusionLimits of agreement between the SpaceLabs 90207 device and the sphygmomanometer differ between IDDM patients and healthy controls. These limits are influenced by the presence of diabetes, age and duration of diabetes. Available protocols for the evaluation of automated blood pressure measurement devices of the British Hypertension Society and the Association for the Advancement of Medical Instrumentation do not consider limits of agreement in subpopulations such as diabetic patients. Therefore, we recommend that tests for the limits of agreement of blood pressure measurement devices for subgroups should be added to these protocols.