Gestational diabetes refers to abnormal blood sugar levels occurring during pregnancy. This term is used if the diagnosis is made during pregnancy, and does not include patients who were already diabetic before pregnancy, who are referred to as having diabetes concurrent with pregnancy. The criteria for diagnosing gestational diabetes are based on the results of the OGTT (Oral Glucose Tolerance Test) conducted between 24-28 weeks of pregnancy. According to the OGTT results, a fasting blood sugar level ≥ 5.1 mmol/L, a one-hour blood sugar level ≥ 10.0 mmol/L, or a two-hour blood sugar level ≥8.5 mmol/L, meeting any one of these criteria confirms a diagnosis of gestational diabetes.