Prolonged (48-hour) modest hyperinsulinemia decreases nocturnal heart rate variability and attenuates the nocturnal decrease in blood pressure in lean, normotensive humans.

Context: Heart rate variability (HRV), an index of cardiac vagal activity, is decreased in individuals with metabolic disease. The relationship between decreased HRV and metabolic disease is unclear. Objective: The objective of this study was to determine whether experimentally induced glucose intolerance decreases HRV in a circadian relevant manner in healthy individuals. Design: This was a within-subject, randomized design study with subjects infused for 48 h with saline (50 ml/h) or 15% glucose (200 mg/m2·min). HRV was evaluated using time domain measurements taken over the 48-h period. Blood pressure and heart rate were monitored, and blood samples were taken. Setting: This study was performed at the General Clinical Research Center of the Hospital of the University of Pennsylvania. Patients: Sixteen healthy subjects (eight men and eight women; 18–30 yr old; mean body mass index, 21.7 ± 1.6 kg/m2) were studied. Results: After glucose infusion, mean plasma glucose was increased by 16.8% (P < 0.0001), a...