This study investigated the actions of non-glycated and glycated glucagon-like peptide-1(7-36)amide (tGLP-1) on glucose uptake and metabolism in isolated mouse abdominal muscle. Monoglycated tGLP-1 (Mr 3463.8) was prepared under hyperglycemic reducing conditions and purified by HPLC. Non-glycated tGLP-1 (10(-10)-10(-8) mol/l) stimulated both 2-deoxy-D-[1-3H]glucose uptake (1.3-1.5 fold) and 14C-glucose oxidation (1.4-1.7 fold) in muscle compared to controls without tGLP-1. Glycation reduced these stimulatory effects by 27-33% and 25% (at 10(-9) mol/l), respectively. tGLP-1 (10(-10)-10(-8) mol/l) promoted muscle glycogenesis and lactate production, whereas glycated peptide was ineffective below 10(-9) mol/l. This study demonstrates that tGLP-1 has potent glycogenic effects in mouse abdominal muscle in vitro and that glycation impairs its action.