When my blood sugar is high, I can take insulin to reduce it. What happens to the sugar in my blood when I inject? Why do I need insulin to facilitate storage of sugar? Couldn’t I just exercise to reduce blood sugar levels and not inject insulin?

When insulin is injected into the subcutaneous tissue and it is absorbed into the blood, it first links to its own receptors on the cells. This leads to opening the door for glucose to enter the cells, stimulating the storing of glucose into the liver and muscles as glycogen, and stimulating the development of fat from excess carbohydrates. This storage of glucose induced by insulin is secondary to the need not to raise blood glucose level above what is normal.

Consider that in a person who does not have diabetes, blood glucose will normally not rise more than 1-2 mmol/L [18-36 mg/dl] after a meal. Any excess of carbohydrates is then transformed, thanks to insulin, into glycogen and fats and stored in the liver, muscles and fat tissue. The ability to store glycogen is limited whilst fat storage in the body is almost unlimited.

Physical exercise can increase the uptake of glucose by exercising muscle, but insulin must be always present in the blood even though the body needs during the exercise might be very small.

MS