Complications of Type 2 Diabetes and Reducing Your Risk of Developing Complications
all information

Complications of Type 2 Diabetes and Reducing Your Risk of Developing Complications

Main Page | Risk Factors | Symptoms | Diagnosis | Treatment | Screening | Complications | Reducing Your Risk | Talking to Your Doctor | Living With Type 2 Diabetes | Resource Guide

En Español (Spanish Version)

The first section of this information sheet deals with possible complications of diabetes. The second section deals with how to lower your chance of developing complications.

Possible Complications

When blood glucose levels are out of the normal range, they cause complications. These include the following:

In the short-term:

In the long-term:

Careful control of your blood sugar can lower your chances of developing these complications. Also, ask your doctor if there are specific medications you can take to decrease the risk of developing these complications.


Hypoglycemia is low blood sugar. Sometimes it is called an "insulin reaction." It is more common in people who take insulin to control their blood sugar, though it can also occur in people who take oral medication, most commonly sulfonylureas. It 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 fairly easily if you recognize the symptoms and treat them right away. The symptoms of hypoglycemia include:

  • Shakiness
  • Dizziness
  • Sweating
  • Hunger
  • Headache
  • Pale skin color
  • Sudden moodiness or behavior change, such as crying for no apparent reason
  • Clumsy or jerky movements
  • Confusion or difficulty paying attention
  • Tingling sensations around the mouth
  • Seizures

If you think you are hypoglycemic, test your blood with your blood glucose monitor. If your blood glucose level is below the range your doctor said was safe, then treat the hypoglycemia. (If you don't know what your safe blood sugar range is, ask your doctor) Or, if you recognize the symptoms of low blood sugar, you may want to treat it immediately, without waiting to test. Safety ranges for blood glucose will vary by individual and are based on your age and other medical conditions.


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:

  • Glucose tablets
  • Cola
  • 1/2 cup of fruit juice
  • 5-6 pieces of hard candy

You should always have some type of sugar with you, so you are prepared to immediately treat hypoglycemia.

Wait 15-20 minutes after eating the sugar, and then retest your blood glucose. If it is still too low, repeat the treatment.

If you pass out from hypoglycemia, you will need immediate, emergency treatment. People who have type 1 diabetes may become prone to hypoglycemic episodes with few warning symptoms. Doctors may give these patients an injectable hormone, glucagon, to use in emergencies.

People with type 2 diabetes usually have warning signs of low blood sugars. If you experience symptoms or episodes of hypoglycemia, you should discuss the events around the episode with your doctor. You should review your current medication regimen to see if it needs adjusting, and you should also strategize about how you can prevent further episodes.


Hyperglycemia is high blood sugar. 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 body, or when your body does not use insulin properly. It can be caused by any of the following:

  • Taking too little insulin or oral medication
  • Eating a larger meal than usual
  • Stress from an illness, such as a cold or flu; or stress from factors in your daily life


Hyperglycemia should be treated immediately to avoid further complications. The signs and symptoms include:

  • High blood sugar—Ask your doctor how often you should check your blood sugar.
  • High levels of sugar in your urine—Ask your doctor if you should be monitoring your urine.
  • Frequent urination (polyuria)
  • Increased thirst (polydipsia)
  • Blurred vision

If hyperglycemia is not promptly treated, it can lead to ketoacidosis, which is also known as diabetic coma. When blood sugar 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 fat breakdown are ketone bodies, which are acids that build up in the blood and cause ketoacidosis.


Chronic high blood sugar as well as high blood pressure can damage tiny blood vessels in the retina of the eye. This damage, called diabetic retinopathy, can occur over a long period of time. Cataract and glaucoma (two other eye conditions) occur almost twice as 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
  • Rings, flashing lights, or blank spots
  • Dark or floating spots
  • Pain or pressure in one or both of your eyes
  • Trouble seeing things out of the corners of your eyes

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, called photocoagulation, or surgery. Quitting smoking and controlling your blood pressure are important preventive measures.

A cataract is a cloud over the lens of your eye. Your lens, which is usually clear, focuses light onto the retina. A cataract makes your vision cloudy. Cataracts are removed with surgery.

Glaucoma is a group of eye diseases caused by a clogging or drainage problem of the fluid in the eye. Eventually there is damage to your eye's main nerve—the optic nerve. The damage first causes you to lose sight from the corners or sides of your eyes. Without treatment, you can go blind. Glaucoma can be treated with special eye drops or laser surgery.

Kidney Disease

Between 30% and 40% of people with diabetes develop diabetic nephropathy after 20 years, a form of kidney damage.

High blood sugar and high blood pressure damage the kidneys’ small blood vessels (capillaries), which 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.

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

People with type 2 diabetes are more likely to have heart disease and to die from heart disease than people without diabetes.

Having diabetes can cause your blood cholesterol levels to rise, leading to clogged, narrowed arteries—a condition called atherosclerosis . Clogged arteries make it more difficult for blood to carry oxygen and other essential nutrients to vital organs and tissues such as you heart, and can cause:

  • Chest pain (angina)—This pain or pressure typically starts in your chest and radiates to your arms and hands. This type of pain may worsen when you exercise or after eating a large meal, and get better when you rest.
  • 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 doesn't receive oxygen and the essential nutrients it needs to function, so it stops working. Symptoms of a heart attack include chest pain, pressure feeling, nausea, indigestion, extreme weakness, and sweating.
  • Cardiomyopathy—This is a general weakening of the heart muscle caused by narrowed, small blood vessels that decrease the blood flow through the heart.


Type 2 diabetes makes you more likely to have a stroke. A stroke is caused by a blockage of blood flow to the brain. The effects of a stroke depend on the part of your brain that is damaged, and may include:

  • Sudden weakness or numbness of your face, arm, or leg on one side of your body
  • Sudden confusion, trouble talking, or trouble understanding
  • Sudden dizziness, loss of balance, or trouble walking
  • Sudden trouble seeing in one or both eyes or sudden double vision
  • Sudden severe headache

Nerve Disease

Diabetes can also cause mild to severe nerve damage, called diabetic neuropathy. Having high blood sugar for many years can damage the blood vessels that bring oxygen to the nerves. High blood sugar can also hurt 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 most susceptible to neuropathy.

The combination of repeated injury, poor blood flow, and poor healing, leads to a greater risk of foot infections that are difficult to treat. In severe cases, when circulation is poor and antibiotics fail to cure the infection, foot and leg amputations may be necessary.

Nerve damage from diabetes may manifest as:

Foot Ulcers

Your feet are especially vulnerable to the effects 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 neuropathy. And then, because of lack of sensation, this area on your foot may be continually re-injured. Therefore, it is essential to wash and examine your feet daily.

According to two recent studies, if you are at high risk for diabetic foot ulcers, checking the temperature of your feet—using an infared skin thermometer—reduces the number of ulcers.*1*2

Lower Your Chances of Complications

Take these steps to protect your health:

  • Have regular checkups even if you feel fine; your doctor can often spot early signs of complications.
  • Strive to keep your blood sugar (fasting level less than 110 mg/dL [6.1 mmol/L]; after meal, level less than 140 mg/dL [7.8 mmol/L]) , glycosylated hemoglobin (less than 7%), and blood pressure (less than 130/85 mmHg) within a healthful range at all times.
  • Don't smoke; if you smoke, quit.
  • Keep your influenza and pneumococal immunization up-to-date.
  • Exercise regularly (e.g., aerobic exercise three to five times a week for 20-60 minutes each time).
  • Keep a close to normal weight.
  • Tell your doctor if you have any of these warning signs:
    • Vision problems, such as blurriness or spots
    • Tiredness
    • Pale skin color
    • Numbness or tingling feelings in hands or feet
    • Repeated infections or slow healing of wounds
    • Chest pain
    • Vaginal itching
    • Constant headaches
    • Cuts or blisters on your feet
  • Ask your doctor if there are any medications that you should take to prevent complications

Depending on your particular situation some of these approaches or medications may help reduce your risk of developing complications.

Intensive Therapy

For many years, patients and doctors alike have asked the question: Does tightly controlling blood sugar, to near normal levels, make a difference in long-term outcomes? Researchers in different countries around the world sought to answer this question by enrolling patients in clinical trials that would last 6-10 years.

The results of three major trials are now known. Patients who were able to intensively control their glucose levels (target: average HbA1c about 7%) had fewer eye, kidney, and neurological complications. These studies also suggest that controlling blood sugar will help reduce the rate of heart attack and stroke.

Two studies done in 2008, though, found that intensive treatment goals (HbA1c < 6.5 %) using the medications rosiglitazone or gliclazide may potentially increase harm.*3,4,6

Intensive control may not be right for everyone. To comply with the regimen, patients must monitor themselves more closely, be willing or able to use insulin, and learn self-management techniques. In addition, patients who aim for intensive control are at greater risk of hypoglycemic episodes.

Talk to your doctor about whether intensive therapy is right for you.


ACE Inhibitors

ACE inhibitors are the name for a class of medications that are generally used to treat high blood pressure and heart failure. These medications work by blocking angiotensin-converting enzyme, 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.

This class of drugs is of particular interest for people with diabetes. There is evidence that these drugs have beneficial effects in patients with diabetes, in addition to lowering blood pressure. A recent clinical trial called HOPE (Heart Outcomes Prevention Evaluation) studied the effect of an ACE inhibitor, ramipril (brand name–Altace) on patients who were at risk for heart disease. A subgroup of these patients also had diabetes.

The bottom line is: the study showed that an ACE inhibitor could reduce the frequency of heart attacks, stroke, and overall death rate in patients at high-risk for cardiovascular events.

There is strong evidence that ACE inhibitors slow the progression of kidney disease in patients with diabetes.

In a trial, researchers found that patients who took ramipril plus telmisartan, a medication to lower high blood pressure, did not have a reduction in mortality or the progression of cardiovascular disease.*5

Talk to your doctor about whether ACE inhibitor therapy is right for you.

Lipid-lowering Therapy

Several studies have found that statins reduce cardiovascular mortality in patients with diabetes who are known to have heart disease (secondary prevention). There is some evidence that more aggressive cholesterol lowering (to an LDL of less than 100 mg/dl [5.6 mmol/L]) may provide even larger cardiovascular benefits.

One study also found that lowering lipid levels prevented the development of heart disease (primary prevention) in patients with diabetes. Talk to your doctor about whether lipid lowering medications are right for you.


People with diabetes are at increased risk of getting heart disease. Taking aspirin may help decrease the risk of getting a heart attack in patients who are at risk for heart disease. Aspirin should be considered for patients who have had a heart attack. Talk to your doctor about whether the benefits of daily aspirin outweigh the risks in your particular case. Aspirin can cause bleeding and interacts with other drugs. It has not been studied in people younger than 30 years old with diabetes.


American Diabetes Association website. Available at: Accessed February 8, 2006.

Gross JL, de Azevedo, Silveviro SP, et al: Diabetic nephropathy: diagnosis, prevention, and treatment. Diabetes Care. 2005;28:176-88.

Heart Protection Study Collaborative Group. MRC/BHF heart protection study of cholesterol lowering with simvastatin in 20536 high-risk individuals: a randomized placebo-controlled trial. Lancet. 2002;360:7-22.

Kendall DM, Riddle MC, Rosenstock J, et al. Effects of Exenatide (Exendin-4) on glycemic control over 30 weeks in patients with type 2 diabetes treated with metformin and a sulfonylurea. Diabetes Care. 2005;28:1083-91.

Lipid control in the management of type 2 diabetes mellitus: a clinical guideline from the American College of Physicians. Annals Internal Med. 2004; 140:644-9.

Molitch ME, DeFranzo, Franz MJ, et al. Diabetic nephrophathy. Diabetes Care. 2003; 26 (Supp 1):S94-8.

Moor H, Summerbell C, Hooper L, et al: Dietary advice for treatment of type 2 diabetes mellitus in adults. The Cochrane Database of Systematic Reviews. 2004;2.

National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health website. Available at: Accessed February 8, 2006.

*12/7/2008 DynaMed Systematic Literature Surveillance Armstrong DG, Holtz-Neiderer K, Wendel C, Mohler MJ, Kimbriel HR, Lavery LA. Skin temperature monitoring reduces the risk for diabetic foot ulceration in high-risk patients. Am J Med. 2007;120:1042-1046.

*22/7/2008 DynaMed Systematic Literature Surveillance Lavery LA, Higgins KR, Lanctot DR, et al. Home monitoring of foot skin temperatures to prevent ulceration. Diabetes Care. 2004;27:2642-2647.

*32/13/2008 DynaMed Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance: For safety, NHLBI changes intensive blood sugar treatment strategy in clinical trial of diabetes and cardiovascular disease. NIH News. National Institutes of Health website. Available at: Accessed February 13, 2008.

*42/21/2008 DynaMed Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance: Major international diabetes study does not confirm increased risk of death reported by US trial. Action in Diabetes and Vascular Disease: PreteraAx and DiamicroN MR Controlled Evaluation (ADVANCE) website. Available at: Accessed February 21, 2008.

*54/10/2008 DynaMed Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance: The ONTARGET investigators. Telmisartan, ramipril, or both in patients at high risk for vascular events. N Engl J Med. 2008 Mar 31 [Epub ahead of print].

* 6 6/18/2008 DynaMed Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance: ADVANCE Collaborative Group. Intensive blood glucose control and vascular outcomes in patients with type 2 diabetes. N Engl J Med. 2008;358:2560-2572. Epub 2008 Jun 6.

Last reviewed April 2007 by David Juan, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

Your Health and Happiness