Symptom awareness is affected by the subjects' expectations during insulin-induced hypoglycemia.
OBJECTIVE
To assess how expectations and symptom beliefs based on a previous episode of insulin-induced hypoglycemia influence symptom awareness after a second insulin injection in healthy subjects.


METHODS
After a first episode of insulin-induced hypoglycemia in session 1, half of 40 healthy male subjects were told at the beginning of session 2 that they would receive human insulin (0.05 IU/kg), the other half saline. According to a 2 x 2 balanced placebo design, only half of each group received the announced substance, whereas the other half received the substance contrary to their expectations. Data collection at 10-15 min intervals included a symptom checklist, blood pressure, heart rate, plasma glucose, and counterregulatory hormone levels.


RESULTS
The expectation of a repeated hypoglycemia clearly influenced the subjects' psychophysiological responses. Without knowledge about the actual treatment, there was only an average maximum confidence of 65% of having received insulin. Expecting the insulin injection led to an increased sum score of neuroglycopenic symptoms but not of autonomic symptoms. Subjects expecting the insulin injection reported more weakness, blurred vision, and inner restlessness than those subjects expecting the saline injection. Those subjects correctly informed about receiving insulin experienced the most drowsiness, dizziness, and headaches. The expectations of the insulin injection increased the norepinephrine levels and the heart rate. The told insulin/given insulin group showed the highest glucagon levels.


CONCLUSIONS
The results support the hypothesis that the subjects' expectations influence their perceived symptoms.
Pohl
J
J
Institute of Psychology, Christian-Albrechts-University, Kiel, Germany. jpohl@psychologie.unikiel.de
Frohnau
G
G
Kerner
W
W
Fehm-Wolfsdorf
G
G
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D001364:Awareness; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure; D004837:Epinephrine / Q000097:blood; D005934:Glucagon / Q000097:blood; D006339:Heart Rate; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007003:Hypoglycemia / Q000139:chemically induced / Q000503:physiopathology* / Q000523:psychology*; D007328:Insulin / Q000008:administration & dosage / Q000009:adverse effects* / Q000097:blood; D008297:Male; D009638:Norepinephrine / Q000097:blood; D010919:Placebos
D001786:Blood Glucose; D007328:Insulin; D010919:Placebos; D000324:Adrenocorticotropic Hormone; D005934:Glucagon; D006854:Hydrocortisone; D009638:Norepinephrine; D004837:Epinephrine