Glucose in humans primarily comes from the foods we eat, especially carbohydrate-containing foods. The body also makes glucose internally through processes like gluconeogenesis when needed. Here’s a concise breakdown:

• Dietary sources
  • Carbohydrates in foods are broken down during digestion into glucose, which enters the bloodstream. This includes starches (bread, rice, pasta), sugars (fruit, dairy, sweets), and other carbohydrate-rich foods. Blood glucose rises after meals as glucose is absorbed from the intestines. [web results context: general physiology of glucose intake and digestion]
• Internal production
  • When blood glucose levels drop, the body can generate glucose internally through gluconeogenesis, using substrates such as lactate, glycerol, and certain amino acids. The liver is a key site for this production. [web results context: liver glycogenolysis and gluconeogenesis]
• Storage and regulation
  • Excess glucose after a meal is stored as glycogen in the liver and muscles, and in times of need, glycogen is broken down back to glucose to maintain blood sugar. Insulin promotes glucose uptake into cells; glucagon stimulates glucose release from liver stores. [web results context: glycemic regulation and glycogen storage]

If you’d like, I can tailor this explanation to a particular context (e.g., physiology class, medical considerations like diabetes, or everyday nutrition).