Randomised comparison of intravenous and subcutaneous routes of glucagon-like peptide-1 administration for lowering plasma glucose in hyperglycaemic subjects with type 2 diabetes.

Subcutaneous GLP-1 administration is much less efficient than intravenous GLP-1 in lowering fasting plasma glucose, with less stimulation of insulin and suppression of glucagon, and much less bioavailability, even at fourfold higher infusion rates.