Before addressing this question, let's first clarify another concept: if diabetes is diagnosed before pregnancy, this is referred to as pre-existing diabetes in pregnancy, which is different from gestational diabetes. Gestational diabetes refers to cases where there is no pre-existing diabetes diagnosis before pregnancy, but abnormal blood glucose levels are detected after becoming pregnant. Generally, a glucose screening test is conducted between the 24th and 28th weeks of pregnancy. Currently in China, there are two approaches: the one-step and the two-step methods. The one-step method involves a direct 75-gram oral glucose tolerance test. However, most of China uses the two-step method, which starts with a 50-gram glucose challenge test. If the blood glucose level one hour after eating is greater than or equal to 7.8 mmol/L, a 75-gram oral glucose tolerance test is recommended. For the 75-gram glucose test, the fasting blood glucose level should generally be less than or equal to 5.6 mmol/L, one hour post-glucose intake should be 10.3 mmol/L, two hours post-glucose should be 8.6 mmol/L, and three hours post-glucose should be 6.7 mmol/L. If two or more of these values exceed the diagnostic criteria, gestational diabetes can be diagnosed. If only one value is abnormal, impaired glucose tolerance can be diagnosed. It is recommended that anyone who experiences abnormal blood glucose levels during pregnancy undergo another 75-gram oral glucose tolerance test six months post-pregnancy to determine if blood glucose levels are still abnormal and whether treatment should continue.