Affiliation:
1. Department of Medicine, Georg-August-University Gottingen
2. Fachklinik fur Diabetes und Stoffwechselkrankheiten Bad Lauterberg
3. Departments of Anatomy and Physiology, Panum Institute, University of Copenhagen Denmark
4. Department of Medicine, Ruhr-University, Knappschafts-Krankenhaus Bochum, Germany
Abstract
OBJECTIVE
Glucagon-like peptide I(7–36) amide (GLP-1) is a physiological incretin hormone that, in slightly supraphysiological doses, stimulates insulin secretion, lowers glucagon concentrations, and thereby normalizes elevated fasting plasma glucose concentrations in type II diabetic patients. It is not known whether GLP-1 has effects also in fasting type I diabetic patients.
RESEARCH DESIGN AND METHODS
In 11 type I diabetic patients (HbA1c 9.1 ± 2.1%; normal, 4.2–6.3%), fasting hyperglycemia was provoked by halving their usual evening NPH insulin dose. In random order on two occasions, 1.2 pmol · kg−1 · min−1 GLP-1 or placebo was infused intravenously in the morning (plasma glucose 13.7 ± 0.9 mmol/l; plasma insulin 26 ± 4 pmol/l). Glucose (glucose oxidase method), insulin, C-peptide, glucagon, GLP-1, cortisol, growth hormone (immunoassays), triglycerides, cholesterol, and nonesterified fatty acids (enzymatic tests) were measured.
RESULTS
Glucagon was reduced from ∼8 to 4 pmol/l, and plasma glucose was lowered from 13.4 ± 1.0 to 10.0 ± 1.2 mmol/l with GLP-1 administration (plasma concentrations ∼100 pmol, P < 0.0001), but not with placebo (14.2 ± 0.7 to 13.2 ± 1.0). Transiently, C-peptide was stimulated from basal 0.09 ± 0.02 to 0.19 ± 0.06 nmol/l by GLP-1 (P < 0.0001), but not by placebo (0.07 ± 0.02 to 0.07 ± 0.02). There was no significant effect on nonesterified fatty acids (P = 0.34), triglycerides (P = 0.57), cholesterol (P = 0.64), cortisol (P = 0.40), or growth hormone (P = 0.53).
CONCLUSIONS
Therefore, exogenous GLP-1 is able to lower fasting glycemia also in type I diabetic patients, mainly by reducing glucagon concentrations. However, this alone is not sufficient to normalize fasting plasma glucose concentrations, as was previously observed in type II diabetic patients, in whom insulin secretion (C-peptide response) was stimulated 20-fold.
Publisher
American Diabetes Association
Subject
Advanced and Specialized Nursing,Endocrinology, Diabetes and Metabolism,Internal Medicine
Cited by
306 articles.
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