Abstract
We investigated loss of the nocturnal decline in blood pressure (BP) and its mechanism in diabetes mellitus with autonomic neuropathy (ANP). BP was measured every 30min using ambulatory BP recorders in 52 diabetic patients and 11 nondiabetic controls, As an index of autonomic nervous dysfunction, CVRR (the coefficient of variation of the R-R interval on ECGs) and diastolic blood pressure response on standing were measured. Plasma volume (PV) was measured with RISA. The difference between daytime mean BP (09: 00 to 13: 00) and nighttime mean BP (01: 00 to 05: 00) was analyzed. The normal control group showed a significant reduction in mean BP during the nighttime (-12.8±7.5mmHg) as compared with the DM group (-3.3±8.6mmHg, p<0.001). The diabetic patients with loss of the nocturnal decline in blood pressure showed autonomic nervous dysfunction and increased PV. In conclusion, the nocturnal elevation of blood pressure might result from an imbalance between reduced tone of sympathetic and parasympathetic functions in addition to the postural effect and increased plasma volume present in diabetic patients.
