Type 1 diabetes occurs when the body's own immune system destroys the insulin-producing cells of the pancreas (called beta cells). Normally, the body's immune system fights off foreign invaders like viruses or bacteria. But for unknown reasons, in people with type 1 diabetes, the immune system attacks various cells in the body. This results in a complete deficiency of the insulin hormone. Normally the hormone insulin is secreted by the pancreas in low amounts. When you eat a meal, sugar (glucose) from food stimulates the pancreas to release insulin. The amount that is released is proportional to the amount that is required by the size of that particular meal. Insulin's main role is to help move certain nutrients -- especially sugar -- into the cells of the body's tissues. Cells use sugars and other nutrients from meals as a source of energy to function. The amount of sugar in the blood decreases once it enters the cells. Normally that signals the beta cells in the pancreas to lower the amount of insulin secreted so that you don't develop low blood sugar levels (hypoglycemia). But the destruction of the beta cells that occurs with type 1 diabetes, throws the entire process into disarray.
Type 1 diabetes
In people with type 1 diabetes, sugar isn't moved into the cells because insulin is not available. When sugar builds up in the blood instead of going into cells, the body's cells starve for nutrients and other systems in the body must provide energy for many important bodily functions. As a result, high blood sugar develops and can cause:
- Dehydration. The build up of sugar in the blood can cause an increase in urination (to try to clear the sugar from the body). When the kidneys lose the glucose through the urine, a large amount of water is also lost, causing dehydration.
- Weight loss. The loss of sugar in the urine means a loss of calories, which provide energy and therefore many people with high sugars lose weight. (Dehydration also contributes to weight loss.)
- Diabetic ketoacidosis (DKA). Without insulin and because the cells are starved of energy, the body breaks down fat cells. Products of this fat breakdown include acidic chemicals called ketones that can be used for energy. Levels of these ketones begin to build up in the blood, causing an increased acidity. The liver continues to release the sugar it stores to help out. Since the body cannot use these sugars without insulin, more sugars piles into the blood stream. The combination of high excess sugars, dehydration, and acid build up is known as "ketoacidosis" and can be life-threatening if not treated immediately.
- Damage to the body. Over time, the high sugar levels in the blood may damage the nerves and small blood vessels of the eyes, kidneys, and heart and predispose a person to atherosclerosis (hardening) of the large arteries that can cause heart attack and stroke.
Unlike people with type 1 diabetes, the bodies of people with type 2 diabetes make insulin. But either their pancreas does not make enough insulin or the body cannot use the insulin well enough. This is called insulin resistance. When there isn't enough insulin or the insulin is not used as it should be, glucose (sugar) can't get into the body's cells. When glucose builds up in the blood instead of going into cells, the body's cells are not able to function properly. Other problems associated with the buildup of glucose in the blood include:
Type 2 diabetes
- Damage to the body. Over time, the high glucose levels in the blood can damage the nerves and small blood vessels of the eyes, kidneys, and heart and lead to atherosclerosis, or hardening of the arteries that can cause heart attack and stroke.
- Dehydration. The buildup of sugar in the blood can cause an increase in urination, causing dehydration.
- Diabetic coma (hyperosmolar nonketotic diabetic coma). When a person with type 2 diabetes becomes very ill or severely dehydrated and is not able to drink enough fluids to make up for the fluid losses, they may develop this life-threatening complication
- Are over 45
- Are obese or overweight
- Have had gestational diabetes
- Have family members who have type 2 diabetes
- Have prediabetes
- Don't exercise
- Have low HDL cholesterol or high triglycerides
- Have high blood pressure
- Are members of certain racial or ethnic groups
Contrary to what you may have heard, there is no single "diabetes diet." That means that the foods recommended for a diabetes diet to control blood glucose (or blood sugar) are good for those with diabetes -- and everyone else. You and your family can eat the same healthy foods at mealtime.
However, for people with diabetes, the total amounts of carbohydrates consumed each day must be monitored carefully. Of the different components of nutrition -- carbohydrates, fats, and proteins -- carbohydrates have the greatest influence on blood sugar levels. Most people with diabetes also have to monitor total fat consumption and protein intake, too.