When blood glucose (sugar) levels are out of the normal range, complications may develop. These include the following:
- In the short-term:
- In the long-term:
Careful control of your blood glucose levels may lower your chance of developing some of these complications. Ask your doctor if there are medications that you should take to further reduce your risk.
Hypoglycemia is more common in people who take insulin to control their glucose levels. But it can also occur in people who take oral medication. Hypoglycemia can be caused by any of the following:
- Taking too much insulin or oral diabetes medication
- Skipping or delaying a meal, or eating a smaller meal than usual
- Exercising harder or longer than your usual pattern
Hypoglycemia can be managed if you recognize the symptoms and treat them right away. The symptoms include:
- Lightheadedness or fainting
- Pale skin color
- Sudden moodiness or behavior change
- Clumsy or jerky movements
- Confusion or difficulty paying attention
- Tingling sensations around the mouth
- Loss of consciousness
If you think you have hypoglycemia, test your blood with a blood glucose monitor. If the glucose level is below the range your doctor said was safe, then treat hypoglycemia. Even when you recognize the symptoms, it is best to use the glucose monitor to make sure that the symptoms you have are really due to hypoglycemia.
Safety ranges for glucose levels vary from person to person. The ranges are based on your age and medical conditions. If you do not know what your safe blood glucose range is, ask your doctor.
The goal of treating hypoglycemia is to quickly raise your blood glucose level to within your safe range. Ask your doctor what the best method of quickly treating hypoglycemia is for you. Common methods of self-treating hypoglycemia include eating or drinking some form of sugar, such as:
- 4 ounces (118 milliliters) fruit juice or regular soda
- 2 tablespoons raisins
- 4 or 5 saltine crackers
- 4 teaspoons sugar
- 1 tablespoon honey or corn syrup
To be prepared, you should always have some type of sugar with you. Wait 15 minutes after eating, and then retest your glucose level. If it is still too low, repeat the treatment. If you pass out from hypoglycemia, you will need emergency treatment. At the hospital, the doctor may give you an injectable hormone called glucagon. Your doctor may also give you a prescription for glucagon if you are at risk of hypoglycemia.
If you have symptoms or episodes of hypoglycemia, talk to your doctor. Also, review your medication to see if it needs to be adjusted. Your doctor can help you to find ways to prevent hypoglycemia.
Long-term hyperglycemia is the major cause of many of the complications that occur in people with diabetes. Hyperglycemia occurs when you do not have enough insulin to remove the glucose in your blood, or when your body does not use insulin properly. It can be caused by:
- Taking too little insulin or oral medication
- Eating a larger meal than usual
- Experiencing stress from an illness or from factors in daily life
Hyperglycemia should be treated right away to avoid further complications. The symptoms include:
- Frequent urination
- Increased thirst
- Blurred vision
- Unexplained weight loss
If hyperglycemia is not promptly treated, it can lead to life-threatening ketoacidosis . This condition happens when glucose levels are so high that very little sugar is available in the cells for energy. The body starts breaking down stored fat for energy. The by-products of this fat breakdown are ketone bodies, acids that build up in the blood and cause ketoacidosis. The condition is more common in type 1 diabetes , but it may occur rarely in type 2 diabetes.
Hyperosmolar Nonketotic Coma
Hyperosmolar nonketotic coma is a life-threatening complication of hyperosmolar hyperglycemic nonketotic syndrome (HHNS), in which your body tries to get rid of excess blood glucose by passing it through your urine. In severe cases, seizures, coma, and death may occur.
The symptoms include:
- Very high blood glucose
- Dry mouth
- Warm, dry skin
- Absence of sweating
- Leg cramps
- Vision loss
- Weakness or strange movements on one side of the body with or without seizures
- Frequent urination
It is important to seek medical attention right away if you think you have symptoms of hyperosmolar nonketotic coma.
Chronic high blood glucose levels, as well as high blood pressure , can lead to damage to tiny blood vessels in the retina of the eye. This damage, called diabetic retinopathy, can occur over a long period of time. Cataracts and glaucoma (two other common eye conditions) occur more often and at a younger age in people with type 2 diabetes than in people without this disease. Signs of eye damage include:
- Blurry or double vision
- Halos, flashing lights, or black spots
- Dark or floating spots
- Pain or pressure in one or both of your eyes
- Trouble seeing things
Some people do not have any symptoms until the damage is significant. Therefore, it is essential to see your eye doctor regularly. Diabetic retinopathy can be treated with laser therapy or surgery. Quitting smoking and controlling your blood pressure are important preventive measures.
Between 20%-40% of people with diabetes develop diabetic nephropathy, a form of kidney damage.
High blood glucose levels and high blood pressure damage the kidney's small blood vessels, called capillaries. These capillaries are responsible for filtering waste out of the blood. This damage allows protein to leak out of the blood and causes wastes that should be excreted with the urine to build up in your blood. Having small amounts of protein in the urine is called microalbuminuria, the first sign of kidney damage.
As damage continues, more protein is leaked and more wastes build up. Having larger amounts of protein in the urine is called proteinuria or macroalbuminuria. This damage can eventually progress to kidney failure , which requires dialysis or a kidney transplant .
Heart Disease and Stroke
People with type 2 diabetes are more likely to have heart disease or stroke compared to people who do not have diabetes. The most common form of heart disease is called coronary artery disease (CAD), blockage of the arteries that bring oxygen-rich blood to the heart muscles. This condition can lead to:
- Chest pain ( angina )—This pain or pressure typically starts in your chest and radiates to your arms (especially the left). This type of pain may appear when you exercise or after eating a large meal and it may get better when you rest.
- Cardiomyopathy —This is a general weakening of the heart muscle caused by narrowed, small blood vessels that decrease the blood flow through the heart. This can progress and cause heart failure .
- Heart attack—This is caused by the blockage of a blood vessel in or near your heart. As a result, part of your heart muscle does not receive oxygen and the essential nutrients it needs to function, so it stops working and dies. Symptoms of a heart attack include: chest pain, pressure feeling, nausea, indigestion, extreme weakness, and sweating.
A stroke can also happen as a result of blood not being able to reach the brain. This may be due to a blockage in a blood vessel. Symptoms of a stroke include:
- Sudden weakness or numbness of your face, arm, or leg on 1 side of your body
- Sudden confusion, trouble talking, or trouble understanding
- Sudden lightheadedness, loss of balance, or trouble walking
- Sudden trouble seeing in 1 or both eyes or sudden double vision
- Sudden severe headache
Diabetes can also cause mild-to-severe nerve damage, called diabetic neuropathy . Having high blood glucose for many years can damage the blood vessels that bring oxygen to the nerves. High blood glucose can also damage the covering on the nerves. Damaged nerves may stop sending messages. Or, they may send messages too slowly or at the wrong times. This can lead to symptoms that range from pain or tingling, to numbness and loss of feeling. The longest nerves in the body are often affected first, leaving the hands and feet more susceptible to neuropathy.
The combination of repeated injury, poor blood flow, and poor healing leads to a greater risk of foot infections that are often difficult to treat. In severe cases, when circulation is poor and antibiotics fail to cure the infection, foot or leg amputations may be necessary.
Other, less severe consequences of nerve damage include:
- Drop in blood pressure when you stand
- Diarrhea at night
- Difficulty in emptying your bladder
- Erectile dysfunction
Your feet are especially vulnerable to the complications of type 2 diabetes. Damage to the peripheral nerves, which go to the arms, hands, legs, and feet, can impair your experience of sensations, such as pain, heat, and cold.
In addition to nerve damage, type 2 diabetes can also cause a decrease in blood flow. Therefore, if you have a blister or sore on your foot , you may not feel it because of the neuropathy. Because of the lack of sensation, this area on your foot may be continually re-injured. It is essential to wash and examine your feet daily. If your doctor recommends it, you may want to use a special skin thermometer to check the temperature of your feet. High foot temperature may be a sign of injury or inflammation.
It is very common to experience mood changes, especially when you have to manage a long-term chronic condition. Depression can undermine your recovery and put you at risk for other complications. Feelings of sadness, hopelessness, and loss of interest in your favorite activities that stay with you for at least 2 weeks should prompt you to call your doctor. Depression is treatable. Your doctor may refer you to counseling to help you better manage your diabetes.
Lower Your Risk of Complications
Take these steps to promote your health:
- Have regular checkups even if you feel fine. Your doctor can often spot early signs of complications.
- Strive to keep your blood glucose levels, hemoglobin A1c (HbA1c) levels, blood pressure, and cholesterol levels within a healthy range at all times. Work with your doctor to determine which levels are safe for you.
- Do not smoke. If you do smoke, talk with your doctor about how you can quit.
- Get vaccinated against the flu and pneumonia .
- Have a regular exercise routine.
- If you are overweight, talk to your doctor about a safe weight loss program.
- Tell your doctor if you have symptoms of any diabetes complications.
- Ask your doctor if there are any medications that you should take to prevent complications. For example, find out if daily aspirin therapy is right for you.
- Keep track of your moods and be alert for persistent depressive symptoms.
Angiotensin-converting enzyme (ACE) inhibitors are the name of a class of medications that are generally used to treat high blood pressure and heart failure. These medications work by blocking angiotensin-converting enzyme. This is a protein that helps the body make angiotensin, which in turn raises blood pressure. Thus, by blocking this enzyme the drug works to lower blood pressure.
ACE inhibitors are generally recommended for patients with diabetes who have high blood pressure, cardiovascular disease, or kidney damage. This medication may decrease the risk of further kidney damage, and reduce the risk of death and heart attacks.
Talk to your doctor about whether ACE inhibitors are right for you.
The American Diabetes Association (ADA) offers these guidelines on low-density lipoprotein (LDL) "bad" cholesterol and coronary heart disease:
- Make lifestyle changes to lower your LDL cholesterol levels. Reduce the amount of saturated fat and cholesterol in your diet. If you are overweight, lose weight. Increase how much physical activity you do each day.
If you do not have cardiovascular heart disease:
- The goal is to have LDL cholesterol level less than 100 mg/dl.
- If you are over age 40 years old and have at least 1 other risk factor for heart disease, treatment goal is a 30%-40% reduction of LDL regardless of baseline LDL levels.
- If you are younger than 40 years old with other risk factors for heart disease and lifestyle changes fail to achieve the desired lipid-lowering goals, the ADA recommends medication.
If you have cardiovascular heart disease:
- The ADA recommends statins to reduce LDL 30%-40% from original values.
- Lowering LDL cholesterol to below 70 using a higher dose of a statin is an option.
- Lower triglycerides to less than 150 mg/dl and raising high-density lipoprotein (HDL) cholesterol to over 40 mg/dl in men and over 50 mg/dl in women are other ADA treatment goals.
The American Heart Association (AHA) offers these recommendations on omega-3 fatty acids :
- All adults should eat fish at least twice weekly.
- If you have coronary heart disease, you should receive at least 1 gram of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) combined every day.
- EPA plus DHA supplement (such as 2-4 grams) is useful in lowering triglyceride levels by 20%-40%.
People with diabetes are at increased risk of getting cardiovascular disease. Taking aspirin may help decrease the risk of having a heart attack in patients who are at risk for heart disease or for those who have heart disease. Talk to your doctor about whether the benefits of daily aspirin outweigh the risks in your case. Aspirin can cause bleeding and interacts with other drugs.
- Reviewer: Kim A. Carmichael, MD, FACP
- Review Date: 09/2014 -
- Update Date: 12/15/2014 -