What is diabetes?

Diabetes is a group of diseases characterized by high levels of blood glucose.  High levels of glucose in the blood result from defects in insulin production, insulin action, and sometimes both.

What is insulin?

Insulin is hormone that is released from the pancreas. The pancreas, a small organ located near the stomach, does many things, but mostly it is involved with digestion.  Ten percent of the pancreas, however, is made up of brilliant machines called beta cells.

Beta cells release insulin into the bloodstream when sugar goes up, as it does after you eat a meal. Insulin’s most important job is to carry nutrients, particularly sugar, from the blood and into the body’s cells.  Since the sugar molecule is too big to enter the cells by itself, insulin helps it.  You can think of insulin as opening the door, and enabling sugar to feed each individual cell.  With sugar, a cell makes energy.  When a cell does not see insulin,  sugar cannot get into it, the cell gets no energy, and it starves.  The sugar remains in the blood, where it is useless.

A healthy beta cell knows exactly how much insulin should be released to get the correct amount of sugar from the bloodstream into the cells.   Normal blood sugar levels range between 80-110mg/dL.

Types of Diabetes

The vast majority of diabetes falls under the category of either Type 1 (also known as juvenile) or Type 2 (adult onset).

Gestational diabetes, which affects 3-10% of pregnant women, usually presents during the third trimester of pregnancy.  It occurs when hormones secreted by the pancreas cause insulin resistance, and usually resolves when the baby is born.   Women who have gestational diabetes, however, are at risk for Type 2 diabetes later in life.

Additionally, there are a variety of uncommon types of diabetes which are caused by infections, drugs, other endocrine disturbances, pancreatic destruction, and genetic defects. These unrelated forms of diabetes are very rare and are classified separately.

Type 1

Type 1 diabetes accounts for 5-10% of the diabetic population.  It is often, but not always, diagnosed in children and young adults.  It usually presents more acutely in younger patients, often requiring hospitalization.  In older people the presentation can be much milder. No one knows what causes Type 1, though experts believe there are genetic and environmental risk factors.  As of now, there is no way to prevent Type 1 diabetes.

In Type 1 diabetes the cells in the pancreas that produce insulin (beta cells) are destroyed, so there is no insulin in the body. The beta cells are destroyed by an autoimmune process.  This means that the body’s own immune system gets confused, and mistakes beta cells for foreign bodies, like bacteria, and it attacks and destroys these cells.   When over 90% of beta cells are destroyed, not enough insulin is produced. It is impossible to live without insulin, but fortunately since 1921 we have been able to replace insulin.

Type 2

Type 2 accounts for about 90% of diabetics. In type 2 diabetes the body produces insulin, but the individual cells don’t respond to it (they are insulin resistant).  It’s as if the cells are asleep.  The beta cells in response then secrete more and more insulin, until the cells finally wake up and let the sugar in.

In a simplistic view, the problem in Type 2 diabetes arises because the beta cells are producing so much insulin, they eventually get tired and stop working, or they don’t work as well.  The treatment for Type 2, therefore, is aimed at making the cells more responsive to insulin and also aimed at helping the beta cells produce more insulin. When those treatments are not enough, insulin therapy is necessary.  A healthy diet and daily exercise are also effective in treating Type 2 diabetes.