Physiological manipulation of psychometric mood factors using acute insulin-induced hypoglycaemia in humans

According to Thayer (The Biopsychology of Mood and Arousal, 1989), the mood states of tense arousal and energetic arousal correlate negatively during 'tense tiredness'. In the present study, acute insulin-induced hypoglycaemia was used to induce tense tiredness. It was hypothesized that levels of tense arousal would be associated with the autonomic manifestations of hypoglycaemia and that energetic arousal levels would be associated with the neuroglycopenic effects of acute hypoglycaemia. Measurements of mood state, symptom score, haemodynamic responses and plasma catecholamine concentrations were made during hypoglycaemia induced by an i.v. infusion of insulin, in 12 healthy male subjects and 15 patients with Type 1 (insulin-dependent) diabetes. Tense arousal rose in both groups of subjects to a peak which coincided with the onset of the acute autonomic reaction, identified by the rapid increase in heart rate and changes in blood pressure which result from neural stimulation within the hypothalamus caused by neuroglycopenia. Energetic arousal decreased significantly in both groups coincidental with the rise in tense arousal and the onset of the acute autonomic reaction. These changes in mood state were concurrent with increments in autonomic and neuroglycopenic symptom scores. This experimental model has allowed induction of a state of 'tense-tiredness' in normal and diabetic humans by using acute hypoglycaemia as a stressful stimulus, confirming to some degree the independence of the two orthogonal mood factors, tense arousal and energetic arousal.