Characteristic patterns of circadian variation in plasma catecholamine levels, blood pressure and heart rate variability in Type 2 diabetic patients

AbstractAims To investigate whether Type 2 diabetic patients exhibit characteristic patterns of circadian variation in plasma levels of catecholamines, blood pressure (BP) and heart rate variability (HRV).Methods Ten Type 2 diabetic and eight control in‐patients were studied. Blood for catecholamine measurement was collected every 4 h, and non‐invasive ambulatory BP and heart rate were monitored throughout the day. HRV was determined using frequency domain methods.Results Diabetic patients showed a different pattern of circadian variation in BP and HRV from that of controls, the diurnal‐nocturnal differences (D‐N) being significantly smaller. The mean 24‐h HRV levels were reduced in diabetic subjects. The mean 24‐h plasma noradrenaline level of 1.36 ± 0.12 nmol/l in diabetic patients was significantly lower than the 2.03 ± 0.20 nmol/l in controls (P < 0.01). In contrast, no significant difference in adrenaline levels was observed. The mean 24‐h plasma noradrenaline level demonstrated a significant positive correlation with D‐N in systolic BP (r = 0.49, P = 0.0153).Conclusions The present study demonstrated distinctive patterns of circadian variation in plasma noradrenaline level