我们禁食时身体如何产生葡萄糖

葡萄糖是我们的主要能源来源，因此重要的是要有生理途径，以防止我们禁食时血糖降低危险性，例如晚上睡觉时。

糖异生：从非碳水化合物产生葡萄糖

这糖异生pathway (see metabolism figure below) synthesises new glucose using non-carbohydrate precursors (glycerol from the breakdown of triglycerides, lactate during anaerobic glycolysis and amino acids from muscle protein degradation). 90% of gluconeogenesis occurs in the liver but some occurs in the kidney too. Insulin regulates gluconeogenesis. The newly made glucose is released back into the blood stream to raise blood glucose levels.

_{Figure: Metabolism is a complex and interlinked process. Gluconeogenesis and glycogenesis are important pathways in metabolism, to raise blood concentrations.}

Glycogenolysis: release of glucose from stored glycogen

In the糖原分解途径（请参见上面的代谢图），可以分解肝糖原以产生葡萄糖，该葡萄糖被释放回血液以增加血糖浓度。这些过程的结合使我们能够保持低但含量的葡萄糖水平，尽管禁食甚至饥饿（请参见下图）。_{图：从储存的糖原中释放葡萄糖}

So you can see from the diagram above that the blood glucose (black line) is kept constant by a combination of processes: release of glucose from the diet (red line), gluconeogenesis (blue) and glycogenolysis (green).