A prospective study of orthostatic blood pressure in diabetic patients.

To clarify whether orthostatic blood pressure is affected by the type of diabetes, cardiac autonomic neuropathy, and the duration of diabetes, orthostatic blood pressure (passive 90 degrees tilt) was evaluated in 102 patients with insulin dependent diabetes mellitus (IDDM), 51 patients with non-insulin dependent diabetes mellitus (NIDDM), and in 238 control subjects in a first study followed up after 8 to 17 years. The heart rate reaction during deep breathing (E/I ratio) and to tilt (acceleration and brake indices) assessed cardiac autonomic function. In the first study, the lowest systolic blood pressure (LSBP) and the lowest diastolic blood pressure (LDBP) after tilt were significantly lower in IDDM patients compared with NIDDM patients (p < 0.001 for LSBP and p < 0.05 for LDBP) and controls (p < 0.001). LDBP was, however, also significantly lower (p < 0.05) in NIDDM patients than in controls. Hence, although most severe in IDDM, LDBP was disturbed in both types of diabetes. In IDDM, a low E/I ratio was associated with disturbed orthostatic blood pressure. At follow-up examinations, orthostatic blood pressure deteriorated in NIDDM but not in IDDM patients. In conclusion, LSBP and LDBP were impaired in IDDM patients compared with NIDDM and control subjects; however, LDBP was also impaired in NIDDM patients compared with controls. When the duration of diabetes increased, orthostatic blood pressure deteriorated in NIDDM but not in IDDM patients.