Glucose is the fuel of life to be burned at the furnace of life (cellular respiration) and diabetes

(to get a big picture of how glucose is burned to produce energy, and to get a general understanding of diabetes.  You need to read the text along the diagram together)

Glucose is the fuel of life. Glucose has to enter cell to be burned in the “great furnace of life” to turn food (represented by glucose here) into energy or ATP (adenosine triphosphate).

There are 4 major steps

1. turn glucose into pyruvate (called glycolysis)

2. turn pyruvate into acetyl CoA (acetyl coenzyme A), so that it can enter citric acid cycle.

3. citric acid cycle (also called Krebs cycle or TCA cycle)

4. electron transport oxidative phosphorylation to produce energy (ATP): details later

The whole process is called cellular respiration that includes many steps of oxidation (adding oxygen in a chemical reaction). So adding oxygen to food (glucose) to produce energy (ATP), is just like we breathe (respiration).

Glycolysis is to turn glucose into pyruvate,which involves about 10 steps, each step needs its enzyme to speed up the chemical reaction.

Hans Krebs figured out citric acid cycle, hence Krebs cycle. In his Nobel lecture he thanked Fritz Lipmann profusely as he knew glycolysis is followed by citric acid cycle that he figured out, but he had no idea how pyruvate will enter the cycle. Working at MGH (Joy's hospital), Fritz Lipmann discovered that pyruvate turns to acetyl CoA, so that it can enter citric acid cycle. They shared 1953 Nobel Prize in Medicine I 1953. Both were German Jewish scientists, both were chased away by Hitler Nazi, Krebs to Engalnd, Lipmann America.

The job of insulin (a hormone secreted by pancreas) is to 'push' glucose into cell to be burned. Without insulin, the process of glucose entering cell is very inefficient.

There are two type of diabetes:

1. Type 1: insulin-producing cells (in pancreas) are somehow destroyed and cannot produce insulin.

2. Type 2 (represents a great majorities): either pancreas doesn't produce enough insulin or body cells not “sensitive” to the action of insulin, called “insulin resistant”, or both.

As I said, insulin is to “push” glucose into cell, if this process is in efficient, we blame the cells being “insensitive” or “resistant” to insulin. (if one has enough insulin, but their job is inefficient, the end result is like not having enough insulin)

So glucose is good stuff (fuel of life), but if glucose cannot enter cell to be burned, it is “wasted”. When we measure blood sugar we measure the amount of glucose (often interchangeable with sugar) circulating in blood. So a diabetic often has high blood sugar (glucose), because they cannot enter cells the way they should..

Glycolysis is to turn glucose into pyruvate,which involves about 10 steps, each step needs its enzyme to speed up the chemical reaction.

Hans Krebs figured out citric acid cycle, hence Krebs cycle. In his Nobel lecture he thanked Fritz Lipmann profusely as he knew glycolysis is followed by citric acid cycle that he figured out, but he had no idea how pyruvate will enter the cycle. Working at MGH (Joy's hospital), Fritz Lipmann discovered that pyruvate turns to acetyl CoA, so that it can enter citric acid cycle. They shared 1953 Nobel Prize in Medicine I 1953. Both were German Jewish scientists, both were chased away by Hitler Nazi, Krebs to Engalnd, Lipmann America.

The job of insulin (a hormone secreted by pancreas) is to 'push' glucose into cell to be burned. Without insulin, the process of glucose entering cell is very inefficient.

There are two type of diabetes:

1. Type 1: insulin-producing cells (in pancreas) are somehow destroyed and cannot produce insulin.

2. Type 2 (represents a great majorities): either pancreas doesn't produce enough insulin or body cells not “sensitive” to the action of insulin, called “insulin resistant”, or both.

As I said, insulin is to “push” glucose into cell, if this process is in efficient, we blame the cells being “insensitive” or “resistant” to insulin. (if one has enough insulin, but their job is inefficient, the end result is like not having enough insulin)

So glucose is good stuff (fuel of life), but if glucose cannot enter cell to be burned, it is “wasted”. When we measure blood sugar we measure the amount of glucose (often interchangeable with sugar) circulating in blood. So a diabetic often has high blood sugar (glucose), because they cannot enter cells the way they should..