Phase I is the high-risk group: Type 2 diabetes originates from “insulin resistance (tissues are insensitive to insulin and need more insulin to lower sugar)”, where the patient can secrete more insulin to fight insulin resistance and keep blood sugar in the normal range. Phase II is the period of impaired blood glucose regulation: when insulin secretion will gradually decrease after reaching the limit, blood glucose starts to rise, and it has not yet reached the diagnosis standard of diabetes. The blood sugar before breakfast is 6.1~6.9mmol/L, and the blood sugar in the hour after meal is 7.8~＜11.1mmol/L. The insulin secreted by patients in this stage is still higher than normal. The third stage is the early stage of diabetes: insulin secretion is further reduced, but still higher than normal, and blood sugar has reached the diagnostic standard of diabetes: blood sugar before breakfast ≥ 7.0mmol/L, and blood sugar 2 hours after meal ≥ 11.1mmol/L. All the above three stages are “hyperinsulinemic stage”, which is one of the independent factors of atherosclerosis. The above three stages are “hyperinsulinemic” and are independent factors of atherosclerosis. The fourth stage is the middle stage: insulin secretion decreases again and is lower than the normal level, and blood sugar further increases. The fifth stage is the late stage of diabetes: when insulin-producing agents (sulfonylureas or glinides) are used for 3 tablets a day and blood glucose is still not controlled, it indicates that it has entered the “insulin secretion failure stage”. From the first stage, arteriosclerosis is gradually formed and remains with the patient for life. After the second stage, the blood glucose rises and diabetic retinopathy, diabetic nephropathy and diabetic neuropathy caused by microangiopathy begin to develop gradually, which will also be accompanied by lifelong. However, patients in stages 1, 2, and 3 are often asymptomatic and easy to ignore for examination. It is only in stages 4 and 5 that the typical symptoms of diabetes may appear and the thought of whether they should go to the hospital can be imagined. Stage I, II, III and IV can be treated with oral hypoglycemic drugs, while stage V can only be treated with insulin. Stage I and II should be actively treated with insulin for a period of time so that pancreatic B-cell function can be restored as much as possible.