Light micrograph of glucose crystals (also called dextrose): a monosaccharide carbohydrate. It is produced by plants during photosynthesis, and stored as starch. In humans it is obtained via hepatic gluconeogenesis and glycogenolysis. This sugar is also synthesized in the intestines, muscles, astrocytes (brain), and kidneys. It acts as a primary energy source in most organisms, from bacteria to humans, through either cellular respiration or fermentation. Glucose plays a role in hormone secretion, gene transcription, and the activity of enzymes and glucoregulatory neurons. Insulin and glucagon pancreatic hormones are critical to maintaining glucose homeostasis in normal and diabetic states. Diabetes is a metabolic disorder in which blood sugar levels are too high. Glucose is listed as an essential medicine. Field of view size: 1.14 x 1.71 mm (0.045 x 0.067 in)