Causes of high fasting blood glucose in gestational diabetes include poor dietary control, Sumuje phenomenon, dawn phenomenon, poor sleep, insomnia, etc. 1. Poor dietary control: Eating before going to bed may lead to higher fasting blood glucose the next day. 2. Sumuji phenomenon: due to overdose of hypoglycemic drugs, hypoglycemia occurs at night (around 2~3 am), and the body produces negative feedback regulation, which increases the secretion of blood glucose-raising hormones (e.g., cortisol, glucagon, etc.), and causes rebound elevation of fasting blood glucose. 3. Dawn phenomenon: Due to the increased secretion of cortisol at dawn, coupled with insufficient insulin, it cannot effectively inhibit the output of hepatic glycogen, resulting in elevated fasting blood glucose. 4. Poor sleep, insomnia: pay attention to the observation of night sleep, if poor sleep or insomnia, can lead to pregnant women fasting blood sugar increase. Gestational diabetes mellitus fasting blood glucose is high, we should consult the doctor in time, to clarify the cause, under the guidance of the doctor treatment.