Pharmacokinetic, insulinotropic, and glucagonostatic properties of GLP-1 [7-36 amide] after subcutaneous injection in healthy volunteers. Dose-response-relationships

Abstract

Intravenous infusions of glucagon-like peptide 1 (GLP-1) [7-36 amide] are glucose-dependently insulinotropic and glucagonostatic and normalize plasma glucose concentrations in non-insulin-dependent diabetic patients. It was the aim of this study to investigate whether subcutaneous GLP-1 [7-36 amide] also has an influence on insulin and glucagon secretion, and which doses are required for significant effects. Therefore, eight healthy volunteers (24 +/- 2 years, body mass index [BMI] 21.9 +/- 2.3 kg/m2) were studied in the fasting state on five occasions in randomized order. Placebo (0.9% NaCl with 1% human serum albumin) or GLP-1 [7-36 amide] in doses of 0.15, 0.5, 1.5 or 4.5 nmol/kg body weight (volume 1 ml or, at the highest dose, 2 ml) was administered subcutaneously. An intravenous glucose bolus (0.33 g/kg body weight) was injected 30 min later. Blood was drawn for the measurement of glucose, insulin, C-peptide, GLP-1 [7-36 amide], and glucagon using specific radioimmunoassays. There were dose-related increments in GLP-1 [7-36 amide] concentrations (p < 0.0001). However, basal values were reached again after 90-120 min. Before glucose administration, insulin (p < 0.0001) and C-peptide (p < 0.0004) increased, whereas glucagon (p = 0.0018) and glucose (p < 0.0001) decreased in a dose-dependent manner. After glucose stimulation, integrated increments in insulin (p = 0.0007) and C-peptide (p = 0.02) were augmented and kG-values increased (p < 0.0001) in a dose-related fashion. The extent of reactive hypoglycaemia was related to the GLP-1 [7-36 amide] dose.(ABSTRACT TRUNCATED AT 250 WORDS)