Insulin and its analogues are essential drugs for people with advanced type II diabetes and for people with type I diabetes. GLP-1 analogs, on the other hand, are a new class of glucose-lowering drugs that are also effective as weight-loss drugs.They both have good market prospects. Insulin and GLP-1 analogues are mostly obtained through microbial fermentation. Their downstream purification routes are complex, requiring a combination of ultrafiltration, ion exchange chromatography and multiple reversed-phase chromatography. The purification process is shown in the following figure: