High and mildly elevated insulin levels during puberty may be a normal physiological phenomenon, or it may be caused by impaired glucose tolerance, diabetes mellitus, Cushing’s syndrome and other diseases. 1. Normal physiological phenomenon: due to the increase of sex hormones and other changes during puberty, the antagonism to insulin is enhanced, resulting in insulin levels may be mildly elevated, which is a normal physiological phenomenon. 2. Diseases: Impaired glucose tolerance, diabetes, Cushing’s syndrome, genetic metabolic diseases and other diseases may lead to high insulin during puberty, which can be diagnosed with fasting blood glucose, glucose tolerance test, glycosylated hemoglobin, hormone and other related tests. If high insulin in puberty, it is recommended to consult a doctor for timely examination.