To understand what is going on inside your body when you have diabetes, it is important to understand how your body works under normal circumstances. What your body does with the glucose it receives from your food, what it does to stabilize your blood sugar level as much as possible, and which substances and cells are working to make this happen. This is also called glucose homeostasis.

How does your body receive glucose?

The food you eat contains carbohydrates (like glucose and starch), fats, and proteins. These are all sources of fuel (energy) and nutrients for your body. Your body needs them to make everything work properly and to grow. Before this happens, your food first needs to be digested (broken down into smaller pieces). The digestion of food takes place in your mouth, stomach, liver, gallbladder, pancreas, small intestines, and colon. Enzymes and hormones play an important role in this process.

If you do not have diabetes

Your body ensures that exactly the right amount of energy and nutrients are being circulated in your blood. Blood sugar remains constant, both before and after a meal, at between 4 and 7 mmol/L (between 72-126 mg/dL, in Belgium and the USA). This is because the amount of glucose (carbohydrates) you ingest and your use of energy is well balanced with the number of enzymes and hormones your body is making.

After a meal

1. The stomach converts glucose from food into simple sugars. These simple sugars can be absorbed from the stomach and gut into the blood.

2. When you see and eat food, the beta cells in your pancreas produce more insulin. They know exactly how much insulin to produce because they also monitor your blood sugar levels. (Insulin is also produced between meals but in very small quantities. This is called the base insulin level.)

3. When you see and eat food, the beta cells in your pancreas produce more insulin. They know exactly how much insulin to produce because they also monitor your blood sugar levels. (Insulin is also produced between meals but in very small quantities. This is called the basal insulin level.)

4. Some of the glucose flows further through your body. All cells in your body are provided with energy this way. They all need glucose to be able to work.

If you eat a lot, you get more carbohydrates (like glucose and starch) than your body needs. If you do not compensate with regular exercise, the excess of carbohydrates is converted into fat which is stored in your fat tissue. If you eat too much fat this is also stored there. There is enough room in the fat tissue to continue to keep growing so a large supply of fat can be built up. The larger the supply, the fatter you get.

What does insulin do?

1. Insulin makes sure glucose can enter the body's cells.

2. Insuline keeps the amount of glucose in your blood stays within normal ranges. Not all cells of your body need insulin to absorb glucose. Cells in your brain, the retinas in your eyes, your kidneys, adrenal glands, and nerve fibres can do this on their own.

When you have diabetes

When you have diabetes, either your body does not make enough insulin, or it makes none at all. When no insulin is produced because the beta cells are damaged, it is called diabetes Type 1. When the amount of insulin produced is not enough and your body does not use the insulin efficiently (insulin resistance), it is called diabetes Type 2.

Diabetes Type 1, after a meal

1. The stomach converts glucose from food into simple sugars. These simple sugars can be absorbed from the stomach and gut into the blood.

2. When you see and eat food, the pancreas cannot respond well because the beta cells are damaged. As a result, no insulin is produced. Without insulin, the glucose in your blood cannot enter the body's cells, even though there is enough glucose being circulated.

3. Meanwhile, your cells are in desperate need of glucose, as fuel. Your body will try to increase the amount of glucose in other ways:

• The glycogen in your liver is converted into glucose (using glucagon, for instance), raising your blood sugar even further, which results in even more glucose being circulated. Some of this you lose through peeing, and because glucose absorbs a lot of fluid you need to pee a lot and frequently. This makes you thirsty and makes you drink a lot too.
• Fats and proteins in your body are broken down to create glucose. During the break-down of fats, fatty acids are released which are converted into ketones by the liver. Part of these ketones end up in your urine. At that time both ketones and glucose can be found in the urine. The break-down of fats and proteins causes you to lose weight and makes you feel sick, tired, and listless.

4. But there is still no insulin to get all the glucose into your body cells. So, you have too little glucose in your cells and too much in your blood, which is harmful and may eventually become life-threatening. The surplus of glucose damages those cells of your body that do not need insulin to absorb glucose (like cells in our kidneys, brain, retinas, and your nervous system). Besides that, too many ketones lower the pH-level of your blood (ketoacidosis). And when you dehydrate from peeing so much, the water deficit will reduce the blood volume and the pH-level of your blood will lower even more. Due to the dehydration combined with the low pH-level of your blood, you could fall into a life-threatening coma, also called a diabetic coma (or diabetic ketoacidosis coma).

Diabetes Type 2, after a meal:

1. The stomach converts glucose from food into simple sugars. These simple sugars can be absorbed from the stomach and gut into the blood.

2. The sensitivity of the liver and muscles to insulin is decreased. The liver is no longer reacting properly to insulin, resulting in too little glucose being converted into glycogen, making the blood sugar rises.

3. The moment you see and eat food, the pancreas responds slower than it should. It takes a long time before extra insulin is produced. Because of this, there is less insulin the moment you need it the most.

4. Because of the lack of insulin and the reduced efficiency of insulin, the blood sugar level is too high. The small amount of insulin and the high blood sugar ensure that a small level of glucose still enters the body's cells.

5. The extra glucose results in a lot of glucose entering body cells that do not need insulin to absorb glucose (like cells in the kidneys, brain, retina, and nervous system). This causes damage to these cells.