The pancreas is the organ in the body that makes insulin. People with diabetes do not have enough insulin, and blood sugars rise. As a general rule, the pancreas is not able to make any insulin in type 1 diabetes (insulin-requiring diabetes); in type 2 diabetes (diabetes that is not usually treated with insulin), the pancreas either makes some insulin (but not enough) or it makes enough insulin, but the body cannot respond (is resistant) to the effects of insulin.

There are exceptions to these generalizations. People with type 1 diabetes (insulin-requiring diabetes) sometimes continue to make insulin for a little while after the diabetes first develops (a time commonly known as the "honeymoon period"). Some with type 2 diabetes (non-insulin-requiring diabetes) also stop making insulin after a while and require insulin injections, just like a person with type 1 diabetes.

In general, children usually have type 1 diabetes (insulin-requiring diabetes), although type 2 (non-insulin-requiring diabetes) is becoming more common in the younger age groups. 

People with type 1 diabetes (insulin-requiring diabetes) generally require insulin injections, while those with type 2 diabetes (non-insulin-requiring diabetes) can often control their blood sugar with pills alone. People with type 2 diabetes (non-insulin-requiring diabetes) usually start with one type of diabetes pill but often require a second or third type of medication to control blood sugar. Some with type 2 diabetes eventually lose the ability to control blood sugar with pills alone and require insulin injections.

Pills to treat type 2 diabetes have different types of actions including:

• Stimulating the pancreas to make more insulin
• Making the body more sensitive to the effects of insulin (decreasing insulin resistance)
• Decreasing the body's production of sugar
• Decreasing the amount of sugar that the body takes in from food

Sulfonylureas (glyburide [DiaBeta, Glynase, Micronase], glimepiride [Amaryl], glipizide, etc.) are the most common pills used for type 2 diabetes and work by stimulating the pancreas to make more insulin. Starlix and Prandin also work by stimulating the pancreas but are very short-acting, so they are not usually used alone to treat type 2 diabetes. Metformin, another common diabetes pill, decreases the body's production of sugar and works especially well in patients who are overweight. Thiazolidinediones (Actos, Avandia) make the body more sensitive to insulin; these drugs only work for patients whose pancreas still makes some insulin, and they are usually used as a third choice after sulfonylureas and metformin. Glyset and Precose decrease the amount of sugar that the body takes in from food, but they tend not to work as well as other medications. They cause few side effects and do not usually cause low blood sugar, which makes them useful for elderly people.

Sometimes, those with type 2 diabetes require insulin injections, in addition to or instead of, pills.

Diabetes can be diagnosed with a blood test that measures the level of sugar (glucose) in the blood. Two different blood tests are available. One is called a "fasting plasma glucose" or FPG, which is the blood sugar level measured after fasting for eight hours.

Another test (the "2-hour plasma glucose" or 2-hr PG) measures blood sugar two hours after drinking a special sugar mixture.Test results are as follows:

• Normal: FPG (fasting plasma glucose) level of less than 110 mg/dl (6.11 mmol/L) or 2-hr PG (2-hour plasma glucose) level of less than 140 mg/dl (7.78 mmol/L)
• Borderline (high, but not enough for a diagnosis of diabetes): FPG (fasting plasma glucose) level of 110 to less than 126 mg/dl (6.11 to less than 7 mmol/L) or 2-hr PG (2-hour plasma glucose) level of 140 to less than 200 mg/dl (7.78 to less than 11.1 mmol/L)
• High (suggests diabetes): FPG (fasting plasma glucose) level of 126 mg/dl or above (7 mmol/L or higher) or 2-hr PG (2-hour plasma glucose) level of 200 mg/dl or above (11.1 mmol/L or higher)

Diabetes can also be diagnosed if a patient has diabetes symptoms and a random blood sugar is 200 mg/dl or above (11.1 mmol/L or higher).

Errors can occur when screening for diabetes, and blood tests should be repeated at least once before the diagnosis is made.

Symptoms of high blood sugar include: increased thirst, hunger, frequent urination, tiredness, blurred vision, and dry itchy skin.

Low blood sugar can cause: weakness, tiredness, dizziness, headache, irritability, heart-pounding, aggressiveness, nausea, nightmares, poor concentration, hunger, sweating, shaking, blurred vision, double vision, slurred speech, sleepiness, pale skin, confusion, seizures, and just feeling "funny".

The cause of type 2 diabetes is unknown. Type 2 diabetes (formerly called "adult onset diabetes") occurs when the pancreas produces some insulin (but not enough) or when the cells of the body are "resistant" (don't respond normally) to insulin.Almost half of all people with type 2 diabetes are significanty overweight. In addition, most overweight people with type 2 diabetes carry most of their excess weight around their waist, a condition called "central obesity". Those with central obesity are at a greater risk of developing type 2 diabetes than overweight people whose excess weight is not primarily located around the waist.

Type 2 diabetes can occur at any time between adolescence and adulthood but is more common in older age groups. It can occur in normal weight individuals but being overweight does increase the chance of developing type 2 diabetes.

Approximately 90 to 95% of all cases of diabetes are type 2.

Type 2 diabetes can occur at any time between adolescence and adulthood but is more common in older age groups. It can occur in normal weight individuals but being overweight does increase the chance of developing type 2 diabetes.

Approximately 90 to 95% of all cases of diabetes are type 2.

For some people, diet and exercise alone are enough to control type 2 diabetes, especially in those who are very overweight. Diet and exercise, alone, tend not to work for people who are of normal weight.

In some patients, these lifestyle approaches alone are not enough, and additional treatment with either pills or insulin injections (shots) may be necessary.