Insulin and Blood Sugar
While the liver is one source of glucose, most glucose the body uses is manufactured from food, primarily carbohydrates. Cells then metabolize, or convert, blood glucose for energy. And insulin is the hormone that makes it all happen.
To visualize the role of insulin in the body and in diabetes, think of a flattened basketball. The ball needs air (or glucose) to supply the necessary energy to bounce. To fill a basketball, you insert an inflating needle into the ball valve to open it, then pump air through it into the ball. Likewise, when a cell needs energy, insulin binds to an insulin receptor, or cell gateway, to “open” the cell and let glucose in for processing.
You can blow pounds and pounds of compressed air at the ball valve, but without a needle to open it, the air will not enter. The same applies to your cells. Without insulin to bind to the receptors and open the cell for glucose, the glucose cannot enter. Instead, it builds up to damaging and toxic levels in the bloodstream.
What Goes Wrong in Diabetes
In people with type 1 diabetes, the inflating needle is missing (no insulin production), or there are only one or two needles to fit an entire court full of basketballs (insufficient insulin production). This happens when the islets (specifically the insulin-producing beta cells) of the pancreas are destroyed.
Most people with type 2 diabetes develop a degree of beta cell death and insulin insufficiency along with the primary cause of their diabetes, insulin resistance.
In people with type 2 diabetes, the inflating needle (the insulin) is the wrong size or shape for the valve (the insulin receptor), or the valve itself is too small or missing. This phenomenon, where there's plenty of insulin but the body isn't using it properly, is known as insulin resistance. And some people with type 1 diabetes can also develop insulin resistance, resulting in what is sometimes referred to as double diabetes.
How it works: the pancreas, glucose, and insulin. Normally, insulin enters the bloodstream to regulate the levels of glucose.
Insulin resistance also occurs in gestational diabetes mellitus (GDM), a type of diabetes that first starts in pregnancy. Gestational diabetes usually resolves itself after childbirth, although women who develop GDM have a higher risk for developing type 2 diabetes later in life.
The Danger of High Blood Glucose
Although the name is almost the same, diabetes insipidus (also known as water diabetes) is completely different from diabetes mellitus. Diabetes insipidus is characterized by excessive thirst and urination that can result in dehydration and/or electrolyte imbalances. It is usually caused by a deficiency in antidiuretic hormone (ADH).
The human body needs glucose to function, but too much glucose circulating in the bloodstream has the potential to be toxic to the insulin-producing beta cells of the pancreas, a problem known as glucotoxicity. When insulin isn't available, blood glucose levels rise higher and higher in the bloodstream.
Fatigue, excessive thirst, and increased urination may appear. These are the classic symptoms many people develop before receiving a diabetes diagnosis. A severe rise in blood sugar can result in diabetic ketoacidosis (DKA) or hyperglycemic hyperosmolar nonketotic coma (HHNC) — both are life-threatening medical emergencies.
Timely diagnosis and treatment are important in preventing diabetes complications. Long-term, elevated blood sugars can damage virtually all the systems of the body. Blood vessel damage can result in cardiovascular disease, neuropathy (nerve damage), retinopathy (retinal eye disease), nephropathy (kidney disease), and more.