A diagnosis of diabetes is made when blood tests show that the amount of glucose in your blood is above a particular level. The glucose level that warrants a diagnosis of diabetes has changed in the past few years and may change in the future as medical experts refine their understanding of this disease. For now, a diagnosis of diabetes is made if one of the following conditions is present:
A casual (any time of day or night) blood glucose of 200 mg/dl or greater accompanied by some of these symptoms: fatigue; frequent urination and thirst; blurred vision; slow healing of skin, gums, and urinary infections; genital itching (particularly in women); and obesity
A fasting (no food for eight hours) blood glucose of 126 mg/dl or greater
A blood glucose of 200 mg/dl or greater two hours after consuming 75 grams of glucose
The term mg/dl is the abbreviation for milligrams per deciliter and describes how much glucose is present in a specific amount of blood. A reading of 70 to 140 mg/dl after eating is considered to be within the normal range. The mg/dl glucose measurement is used in the United States. Most of the rest of the world uses the International System (IS), in which the units are mmol/L (millimoles per liter). To find your mmol/L level, divide mg/dl by 18 (for example, 200 mg/dl is 11.1 mmol/L).
To make a diagnosis of diabetes, it's not enough for one of these conditions to be present on only one occasion. The same one or one of the other two conditions must be found another time.
Types of diabetes
There are two major types of diabetes:
Type 1 diabetes: Once called juvenile diabetes, this disease usually begins in childhood and results from destruction of the cells of the pancreas that produce insulin. Insulin is the key chemical in the body responsible for getting glucose (blood sugar) into cells where it can be used for energy. Storage of food for energy depends on the presence of insulin.
Type 2 diabetes: Formerly called adult-onset diabetes, this disease often begins in adults, usually after age 40. It results not from an absolute lack of insulin, like type 1, but from a resistance to the action of insulin, called insulin resistance. People with type 2 diabetes are often overweight, but this type can occur regardless of whether a person is overweight. The pancreas of people with type 2 diabetes often makes more than the normal amount of insulin to keep up with the demands of the body.
The major difference between the two types is that no insulin is found in the body in type 1 diabetes, but a normal to increased amount of insulin is found in people with type 2 diabetes.
A less frequent but important type of diabetes is gestational diabetes, which occurs during pregnancy in women who didn't have diabetes before they became pregnant. This disease results when tissues associated with pregnancy make a large amount of different chemicals that oppose the action of insulin. Gestational diabetes is more like type 2 than type 1 diabetes. Gestational diabetes is important not just because it can lead to premature and difficult birth, but because a woman who has it is at higher risk of developing type 2 diabetes later in life. The diabetes generally disappears after the baby is born but can reappear during later pregnancies and even without a pregnancy.
Consequences of diabetes
Before insulin became available in 1922, people with type 1 diabetes rarely lived a normal life span. Unable to store fat or glucose, the diabetic body begins to break down its lean tissue, mostly muscle, and the person wastes away. Insulin was a lifesaver, but its properties allowed people to live long enough to suffer the consequences of untreated high blood glucose. These consequences are divided into three major groups: the irritations of diabetes, the short-term complications of diabetes, and the long-term complications. All three sets of problems may occur in type 1 or type 2 diabetes, although the short-term complications are more severe in type 1, resulting from the total lack of insulin.
Irritations of diabetes
The irritations of diabetes are the signs and symptoms that accompany a high blood glucose level. The glucose level is not high enough to be life-threatening, but it definitely affects the lifestyle of the person with diabetes.
These irritations may be so mild that they aren't even thought of as signs or symptoms of a disease. The most important of these irritations include the following:
Frequent urination and thirst
Genital itching, particularly in women
Gum and urinary infections
Among the short-term complications are
Ketoacidosis: Insulin is the key that permits glucose to enter cells. If you lack insulin, your cells can't use glucose for energy, so you begin to burn body fat instead. The process of breaking down fat for energy creates ketones. The accumulation of large amounts of ketones makes the blood acidic. Ketoacidosis happens in type 1 diabetes but rarely in type 2.
Hyperosmolar syndrome: Because of advanced age or other factors, your kidneys may have trouble removing glucose from your body. If you happen to lose a large amount of fluid due to sickness or neglect, your blood volume decreases, which makes it even harder for your kidneys to remove glucose. Your blood glucose level can skyrocket. Eventually, the level of blood glucose becomes so high that the blood is like syrup. This complication happens in type 2 diabetes when severe dehydration is present.
Hypoglycemia or low blood glucose: This complication results from excessive treatment with agents that lower blood glucose levels, not eating enough when these agents are used, or excessive exercise.
People who have any type of diabetes are subject to long-term complications. These complications are broken down into two groups: microvascular (small blood vessels) and macrovascular (large blood vessels).
The microvascular complications include
Diabetic retinopathy: Eye damage that can lead to blindness if untreated.
Diabetic nephropathy: Kidney damage that can lead to kidney failure if not treated.
Diabetic neuropathy: Nerve damage resulting in many different symptoms, the most common of which is loss of sensation, tingling, and numbness in the feet and hands.
The macrovascular complications consist of
Arteriosclerotic heart disease: The blood vessels that supply blood to heart tissue are blocked. This is the most common cause of death in people with diabetes, just as it is in people who do not have diabetes.
Arteriosclerotic cerebrovascular disease: The arteries to the brain are blocked, leading to stroke or sometimes loss of intellectual function.
Arteriosclerotic peripheral vascular disease (PVD): The arteries that carry blood to the legs become narrowed or clogged. If blood flow ceases completely, amputation may be necessary.