Dexamethasone treatment fails to increase arginine-induced insulin release in healthy subjects with low insulin response.
We have compared insulin responses to L-arginine before and during dexamethasone treatment in healthy subjects, previously classified as subjects with either high or low insulin response according to a standardized glucose infusion test. Arginine stimulation was administered as a 150 mg/kg bolus followed by 10 mg.kg-1.min-1 to six subjects with high insulin response and to seven subjects with low insulin response. Before dexamethasone treatment the incremental insulin level during 0-10 min of arginine was higher in subjects with high (36.5 +/- 6.8 microU/ml) than in subjects with low response (14.5 +/- 2.3 microU/ml), p less than 0.01 for difference. Dexamethasone treatment (6 mg/day for 60 h) markedly enhanced the insulin response to arginine in subjects with high response (+99% 0-30 min) but failed to affect the subjects with low response (+4% 0-30 min). The C-peptide response to arginine exhibited similar differences between groups. Decreased responsiveness to arginine in subjects with low insulin response, especially during dexamethasone treatment, suggests a Beta-cell capacity defect although a decreased potentiating-sensing effect of glucose cannot be completely ruled out.
Grill
V
V
Department of Endocrinology, Karolinska Hospital, Stockholm, Sweden.
Alvarsson
M
M
Efendic
S
S
D000328:Adult; D001120:Arginine / Q000494:pharmacology*; D001786:Blood Glucose / Q000378:metabolism*; D002096:C-Peptide / Q000097:blood / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D000078790:Insulin Secretion; D007700:Kinetics; D012016:Reference Values; D013997:Time Factors
D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D003907:Dexamethasone; D001120:Arginine