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- Date Published | June 4, 2018
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- Health Library | Disease & Conditions | Diabetes Mellitus: An Overview
Diabetes Mellitus: An Overview
What is diabetes mellitus?
Diabetes mellitus is a disease that prevents your body from properly using the energy from the food you eat. Diabetes occurs in one of the following situations:
- The pancreas (an organ behind your stomach) produces little insulin or no insulin at all. (Insulin is a naturally occurring hormone, produced by the beta cells of the pancreas, which helps the body use sugar for energy.)
- The pancreas makes insulin, but the insulin made does not work as it should. This condition is called insulin resistance.
To better understand diabetes, it helps to know more about how the body uses food for energy (a process called metabolism). Your body is made up of millions of cells.
To make energy, the cells need food in a very simple form. When you eat or drink, much of your food is broken down into a simple sugar called glucose. Glucose provides the energy your body needs for daily activities.
The blood vessels and blood are the highways that transport sugar from where it is either taken in (the stomach) or manufactured (in the liver) to the cells where it is used (muscles) or where it is stored (fat). Sugar cannot go into the cells by itself. The pancreas releases insulin into the blood, which serves as the helper, or the "key," that lets sugar into the cells for use as energy.
When sugar leaves the bloodstream and enters the cells, the blood sugar level is lowered. Without insulin, or the "key," sugar cannot get into the body's cells for use as energy. This causes sugar to rise. Too much sugar in the blood is called "hyperglycemia" (high blood sugar) or diabetes.
What are the types of diabetes?
There are two main types of diabetes: Type 1 and Type 2:
- Type 1 diabetes occurs because the insulin-producing cells of the pancreas (beta cells) are damaged. In Type 1 diabetes, the pancreas makes little or no insulin, so sugar cannot get into the body's cells for use as energy. People with Type 1 diabetes must use insulin injections to control their blood glucose. Type 1 is the most common form of diabetes in people who are under age 30, but it can occur at any age. Ten percent of people with diabetes are diagnosed with Type 1.
- In Type 2 diabetes, the pancreas makes insulin, but it either doesn't produce enough, or the insulin does not work properly. Nine out of 10 people with diabetes have Type 2. This type occurs most often in people who are over 40 years old and overweight. Type 2 diabetes may sometimes be controlled with a combination of diet, weight management, and exercise. However, treatment also may include oral glucose-lowering medications (taken by mouth) or insulin injections (shots).
Other types of diabetes might result from pregnancy (gestational diabetes), surgery, use of certain medicines, various illnesses, and other specific causes.
What is gestational diabetes?
Gestational diabetes occurs when there is a high blood glucose level during pregnancy. As pregnancy progresses, the developing baby has a greater need for glucose. Hormone changes during pregnancy also affect the action of insulin, which brings about high blood glucose levels.
Pregnant women who have a greater risk of developing gestational diabetes include those who:
- Are over 25 years old
- Are above their desired body weight
- Have a family history of diabetes
- Are Hispanic, African-American, Native American, or Asian-American.
Blood glucose levels usually return to normal after childbirth. However, women who have had gestational diabetes have an increased risk of developing Type 2 diabetes later in life.
What causes diabetes?
The causes of diabetes are not known. The following factors may increase your chance of getting diabetes:
- Family history of diabetes or inherited tendency
- African-American, Hispanic, Native American, or Asian-American race, Pacific Islander or ethnic background
- Being overweight (20 percent or more over your desired body weight)
- Physical stress (such as surgery or illness)
- Use of certain medications, including steroids and blood pressure medications
- Injury to the pancreas (such as infection, tumor, surgery, or accident)
- Autoimmune disease
- High blood pressure
- Abnormal blood cholesterol or triglyceride levels
- Age (risk increases with age)
- Alcohol (risk increases with years of heavy alcohol use)
- History of gestational diabetes or delivery of a baby weighing more than 9 pounds (4.1 Kg).
It is important to note that sugar itself does not cause diabetes. Eating a lot of sugar can lead to tooth decay, but it does not cause diabetes.
What are the symptoms of diabetes?
The symptoms of diabetes include:
- Increased thirst
- Increased hunger (especially after eating)
- Dry mouth
- Frequent urination
- Unexplained weight loss (even though you are eating and feel hungry)
- Weak, tired feeling
- Blurred vision
- Numbness or tingling in the hands or feet
- Slow-healing sores or cuts
- Dry and itchy skin (usually in the vaginal or groin area)
- Frequent yeast infections
What are the symptoms of low blood sugar?
Most people have symptoms of low blood sugar (hypoglycemia) when their blood sugar is less than 60 mg/dl. (Your health care provider will tell you how to test your blood sugar level.)
When your blood sugar is low, your body gives out signs that you need food. Different people have different symptoms. You will learn to know your symptoms.
Common early symptoms of low blood sugar include the following:
- Feeling weak
- Feeling dizzy
- Feeling hungry
- Trembling and feeling shaky
- Pounding heart
- Pale skin
- Feeling frightened or anxious
Late symptoms of low blood sugar include:
- Feeling confused
- Feeling cranky
- Poor coordination
- Bad dreams or nightmares
- Being unable keep your mind on one subject
- Numbness in your mouth and tongue
- Passing out
Diagnosis and Tests
How is diabetes diagnosed?
Diabetes is diagnosed with fasting sugar blood tests or with A1c blood tests, also known as glycated hemoglobin tests. A fasting blood sugar test is performed after you have had nothing to eat or drink for at least eight hours. Normal fasting blood sugar is less than 100 mg/dl (5.6 mmol/l). You do not have to be fasting for an A1c blood test. Diabetes is diagnosed by one of the following (see chart):
- Your blood sugar level is equal to or greater than 126 mg/dl (7 mmol/l).
- You have two random blood sugar tests over 200 mg/dl (11.1 mmol/l) with symptoms.
- You have an oral glucose tolerance test with results over 200 mg/dl (11.1 mmol/l).
- Your A1c test is greater than 6.5% on two separate days.
An A1c test should be performed in a laboratory using a method that is certified by the National Glycohemoglobin Standardization Program (NGSP) and standardized to the Diabetes Control and Complications Trial (DCCT) assay.
- Fasting Glucose Test
- Normal: Less than 100
- Pre-diabetes: 100-125
- Diabetes: 126 or higher
- Random (anytime) Glucose Test
- Normal: Less than 140
- Pre-diabetes: 140-199
- Diabetes: 200 or higher
- A1c Test
- Normal: Less than 5.7%
- Pre-diabetes: 5.7 - 6.4%
- Diabetes: 6.5% or higher
Management and Treatment
How is diabetes managed?
There is no cure for diabetes, but it can be treated and controlled. The goals of managing diabetes are to:
- Keep your blood glucose levels as near to normal as possible by balancing food intake with medication and activity.
- Maintain your blood cholesterol and triglyceride (lipid) levels as near the normal ranges as possible by decreasing the total amount of fat to 30% or less of your total daily calories, and by reducing saturated fat and cholesterol.
- Control your blood pressure. (Your blood pressure should not go over 130/80.)
- Decrease or possibly prevent the development of diabetes-related health problems.
You hold the keys to managing your diabetes by:
- Planning what you eat and following a balanced meal plan.
- Exercising regularly.
- Taking medication, if prescribed, and closely following the guidelines on how and when to take it.
- Monitoring your blood glucose and blood pressure levels at home.
- Keeping your appointments with your health care providers and having laboratory tests completed as ordered by your doctor.
What you do at home every day affects your blood glucose more than what your doctor can do every few months during your check-up.
What are insulin pumps?
Insulin pumps are small, computerized devices, about the size of a beeper that you wear on your belt or put in your pocket. They have a small flexible tube with a fine needle on the end. The needle is inserted under the skin of your abdomen and taped in place. The pump releases a carefully measured, steady flow of insulin into the tissue. Insulin pumps can cost $6,000 to $10,000 for the pump, with additional costs for necessary supplies to use the pump.Using a pump means you will have to monitor your blood sugar level at least four times a day. You program doses and make adjustments to your insulin, depending on your food intake and exercise program. Some health care providers prefer the insulin pump over injections because its slow release of insulin imitates a working pancreas.
Can I take both pills and insulin to control my blood sugar?
Yes. The combination of insulin and an oral medication, when taken as directed by your doctor, is very safe and effective in controlling blood sugar. A typical combination therapy consists of taking an oral medication during the day and insulin at night. Once you begin taking insulin, you will need to monitor your blood sugar more often to reduce the risk of low blood sugar reactions.Combination therapies are often helpful for people who have Type 2 diabetes (adult onset diabetes). If you have been taking an oral medication, your doctor may change your treatment plan to include insulin injections. This change is often made to help people with Type 2 diabetes gain better control of their blood sugar.
Can diabetes be cured?
No. A cure for diabetes has not yet been found. However, diabetes can be treated and controlled. Most people with diabetes manage their disease and lead normal lives.
What are some of the long-term complications of diabetes?
- Retinopathy (eye disease): All patients with diabetes should see an ophthalmologist (eye specialist) every year for a dilated eye examination. Patients with known eye disease or symptoms of blurred vision in one eye or who have blind spots may need to see their ophthalmologist more often.
- Nephropathy (kidney disease): Urine testing should be performed every year. Regular blood pressure checks also are important because control of high blood pressure is essential in slowing kidney disease. Generally, blood pressure should be less than 130/80 in adults. Persistent swelling in the leg or feet also may be a symptom of kidney disease and should be reported to your doctor.
- Neuropathy (nerve disease): Numbness or tingling in your feet should be reported to your doctor at your regular visits. Check your feet every day for redness, calluses, cracks, or breakdown in the skin tissue. If you notice these symptoms before your scheduled visits, notify your doctor immediately.
Other long-term complications may include:
- Eye problems, including glaucoma and cataracts
- Dental problems
- High blood pressure
- Heart disease
- American Diabetes Association. Diabetes Basics Accessed 5/3/2017.
- The National Institute of Diabetes and Digestive and Kidney Diseases. What is Diabetes? Accessed 5/3/2017.
- American Diabetes Association. A1C and eAG Accessed 5/3/2017.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 04/07/2017