In our previous studies, we constructed some genetically engineered strains based on a single-plasmid genome editing system within lactic acid bacteria to continuously produce GLP-1, which demonstrated positive therapeutic outcomes in obesity mice, neuropsychiatric disease, T2DM mice, and even in T2DM monkeys [27–29]. The gene discussed is GCG; the disease is obesity due to melanocortin 4 receptor deficiency.