Insulin resistance in Graves' disease: a quantitative in-vivo evaluation.
Hyperthyroidism is considered to be an insulin-resistant state, but a quantitative evaluation of some action of insulin is still lacking. We performed euglycaemic clamp at about 350 and 7000 pmol l-1 plasma insulin concentration in combination with the 3H-glucose infusion in 12 patients with Graves' disease and in 12 matched controls. Fasting plasma insulin (126 +/- 6.5 vs. 77.5 +/- 5.7 pmol l-1; P less than 0.001), C-peptide (502 +/- 36 vs. 363 +/- 41 pmol l-1; P less than 0.001) and glucagon (47 +/- 3.3 vs. 33.3 +/- 3 pmol l-1; P less than 0.01) were significantly higher in hyperthyroids than in euthyroids. Basal hepatic glucose production was significantly higher in hyperthyroids than in euthyroids (18.3 +/- 1.4 vs. 9.2 +/- 0.5 mumol l-1; P less than 0.0001), and its suppression during physiological hyperinsulinaemia was only 50% in hyperthyroids. Glucose utilization and suppression of lipolysis were normally stimulated by insulin. All parameters altered during hyperthyroidism were normalized during methimazole-induced euthyroidism. We conclude that insulin resistance involves mainly glucose rather than lipid and is selective at the hepatic level.
Cavallo-Perin
P
P
Institute of Internal Medicine, University of Turin, Italy.
Bruno
A
A
Boine
L
L
Cassader
M
M
Lenti
G
G
Pagano
G
G
D000328:Adult; D001786:Blood Glucose; D002096:C-Peptide / Q000097:blood; D005260:Female; D005934:Glucagon / Q000097:blood; D005947:Glucose / Q000096:biosynthesis; D006111:Graves Disease / Q000503:physiopathology*; D006801:Humans; D007328:Insulin / Q000097:blood* / Q000378:metabolism; D007333:Insulin Resistance; D000078790:Insulin Secretion; D008099:Liver / Q000378:metabolism; D008297:Male; D008875:Middle Aged
D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D005934:Glucagon; D005947:Glucose