Why blood glucose levels are controlled in people who do not have diabetes?

Blood glucose levels are controlled in people who do not have diabetes through a complex interplay of hormones, organs, and tissues. Here are the key mechanisms involved:

1. Insulin and Glucagon:

- Insulin, produced by the pancreas, helps cells absorb glucose from the bloodstream and store it as glycogen (in the liver and muscles) or fat (adipose tissue).

- Glucagon, also produced by the pancreas, opposes insulin's actions and stimulates the liver to convert stored glycogen back into glucose, raising blood sugar levels.

2. Glucose Homeostasis:

- When blood glucose levels rise after a meal, the pancreas releases insulin. Insulin binds to cells throughout the body, allowing glucose to enter and be used for energy or stored as glycogen.

- When blood glucose levels drop, the pancreas reduces insulin production and releases glucagon. Glucagon signals the liver to release stored glucose into the bloodstream, bringing glucose levels back up.

3. Feedback Mechanisms:

- The body constantly monitors blood glucose levels through specialized cells called beta cells in the pancreas.

- If blood glucose levels are high, beta cells release insulin, triggering a negative feedback loop to lower glucose levels.

- Conversely, low blood glucose levels cause beta cells to reduce insulin secretion and release glucagon, bringing glucose levels back up.

4. Hepatic Glucose Production and Utilization:

- The liver plays a crucial role in maintaining glucose homeostasis. It can store glucose as glycogen and release glucose when needed.

- When blood glucose levels are low, the liver can convert stored glycogen into glucose through a process called glycogenolysis.

- Additionally, the liver can produce glucose from non-carbohydrate sources, like amino acids and fats, in a process called gluconeogenesis.

5. Peripheral Glucose Uptake:

- Tissues like skeletal muscle and adipose tissue also play a role in glucose control.

- Insulin stimulates the transport of glucose into these tissues, promoting their uptake and utilization.

6. Hormonal Influences:

- Certain hormones, such as epinephrine (adrenaline), cortisol, and growth hormone, can affect blood glucose levels.

- These hormones can stimulate the breakdown of glycogen and release glucose into the bloodstream, counteracting the effects of insulin.

In healthy individuals, these mechanisms work in a coordinated manner to maintain blood glucose levels within a narrow range, ensuring the proper functioning of cells and tissues throughout the body.