Circulating insulin inhibits glucagon secretion induced by arginine in type 1 diabetes.
OBJECTIVE
To evaluate if insulin has a suppressive effect on the glucagon secretion stimulated by arginine in type 1 diabetes.


METHODS
The alpha-cell response to an i.v. bolus of arginine (150mgkg(-1)) followed by an infusion of arginine (10mgkg(-1)min(-1)) was studied in random order during either low dose infusion (LDT) or high dose infusion (HDT) of insulin in ten patients with type 1 diabetes. The blood glucose level was clamped at an arterialized level of 5mmoll(-1) by a variable infusion of glucose. Venous C-peptide, glucagon, growth hormone, and insulin were analyzed.


RESULTS
The mean plasma concentration of insulin was four times higher during the HDT. The C-peptide level did not differ between the LDT and the HDT. During the LDT in response to arginine the blood glucose level increased from 5.0 to 5.8mmol l(-1) although the glucose infusion was markedly reduced, while no change was seen during the HDT. A significantly smaller increase in the glucagon levels during the HDT was seen (area under the curve of 413+/-45 vs 466+/-44pgml(-1)h(-1), P=0.03) while the growth hormone levels were almost identical.


CONCLUSIONS
This study demonstrates that a high level of circulating insulin exerts an inhibitory effect on the glucagon response to arginine in type 1 diabetes. Thus, the suppressive effect of insulin on the glucagon release from the alpha-cell seems to be general and not only dependent on stimulation by hypoglycemia.
Oskarsson
P R
PR
Department of Medicine, Danderyd Hospital, Karolinska Institutet, Stockholm, Sweden. Per.Oskarsson@med.ds.sll.se
Lins
P E
PE
Ahré
B
B
Adamson
U C
UC
D000328:Adult; D001120:Arginine / Q000494:pharmacology*; D001786:Blood Glucose / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000188:drug therapy; D004305:Dose-Response Relationship, Drug; D005260:Female; D005934:Glucagon / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000097:blood*; D007262:Infusions, Intravenous; D007328:Insulin / Q000008:administration & dosage* / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000166:cytology / Q000378:metabolism
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D005934:Glucagon; D001120:Arginine