Growing evidence indicates links between type 2 diabetes and Parkinson's disease. The glucagon-like peptide 1 analogue, liraglutide, a commonly used anti-diabetic drug, has protective effects on neurons. The goal of this study was to determine whether long-term liraglutide treatment could reduce the risk of adult type 2 diabetic mice developing Parkinson's disease. Male diabetic db/db mice (12 weeks old) were injected daily with liraglutide (n = 8), or saline (n = 8), and non-diabetic m/m littermates (n = 6) were included as controls. Motor function was assessed every 4 weeks and all mice were sacrificed after 8 weeks of drug intervention for further analysis. The results revealed that long-term treatment of liraglutide protected the db/db mice against the motor function decay and the dopaminergic neuron loss. Liraglutide also restored the impaired AMP kinase (AMPK)/peroxisome proliferator-activated receptor-gamma coactivator 1a (PGC-1a) signaling in the striatum of db/db mice. Further experiments in SH-SY5Y cells supported that AMPK is involved in the neuroprotective effect of liraglutide. In summary, long-term liraglutide ameliorated motor dysfunction and dopaminergic neuron impairment in type 2 diabetic mice, probably via enhancing AMPK/PGC-1a signaling.