High blood glucose is not necessarily diabetes, but may also be caused by inappropriate timing of blood glucose measurement, certain medications, physiological factors, other diseases and other causes of elevated blood glucose. 1. Inappropriate timing of blood glucose measurement: Fasting blood glucose measurement after breakfast will result in high fasting blood glucose, or excessive sugar consumption before blood glucose measurement will result in high fasting blood glucose or high postprandial blood glucose. 2. Certain drugs: high blood sugar may occur after taking glucocorticoid drugs, such as prednisone. 3. Physiological factors: blood glucose may also be elevated in the case of emotional excitement, overfeeding and so on. 4. Other diseases: high blood glucose may also occur in some pathological conditions, such as adrenal hyperplasia, serious infections and other diseases. If you have high blood glucose, you should consult a doctor as soon as possible to avoid delaying your condition.