When in the human body (organs Pancreas+liver) is unable to produce insulin, then it leads to a condition called Diabetes when the blood sugar level increases to damage many functional organs including metabolic problems.
Insulin is then injected in the human body for metabolic function.
Insulin currently cannot be taken by mouth, because it is a protein, and the gastric juices in the stomach would destroy it. So by injecting it under the skin, you are enabling the insulin to eventually get into the blood stream without having it get destroyed in the stomach. There is considerable research going on to try to resolve this problem--studies are ongoing to develop a pill form.
The body's blood cells cannot absorb the sugar/glucose needed to give energy.
No; insulin causes cells to absorb glucose.
The islets of Langerhans are located in the pancreas and they secrete insulin, which stimulate the cells to absorb glucose in the bloodstream (lowering blood sugar).
Insulin is a hormone that causes cells to absorb and store glucose. When the body fails to produce sufficient insulin, or the insulin is ineffective, the body cannot store glucose, and can become lethargic. Diabetes is the name for the condition where insulin is not functioning properly.
An allostasis is when your body adjusts to changes. For example, your body releases hormones before a meal. These are chemicals. They control activities in your body. Hormones include insulin and ghrelin. Insulin allows your body to absorb sugars in your blood. Ghrelin makes you hungry before meals. The release of these hormones makes your body ready for incoming calories ahead of time.
Insulin.
I'm not an expert on this subject, but I do know that insulin levels have to keep up with the amount of sugar in your blood. Your cells can't use the sugar to produce energy without the insulin to help them absorb it. Homeostasis is the chemical reactions in the body, so the insulin must help cells absorb sugar so they can have the chemical reaction that produces energy. Like I said, I'm not the expert, but I hope that helps!
Insulin is produced in your pancreas.
It is the insulin produced by your own body
No, body weight does not increase drom an insulin injection.
pancreas
Insulin is usually made in your body automatically; diabetes is when your body does not make enough insulin. So some people with diabetes have to take insulin to control their blood sugar.