By Amy Adams, MS

Reviewed By Jeremy Walston, MD
Last Updated September 15, 2000

In people with Type 2 diabetes, muscle and fat cells are less able to take up a sugar called glucose from the blood. The sugars build up to very high levels, which can damage the blood vessels, nerves, kidneys, and eyes.

Most diabetes treatment plans lower a diabetic's blood sugar level to some extent, but do not achieve the levels of a nondiabetic person. A recent study called the United Kingdom Prospective Diabetes Trial (UKPDT), however, found that keeping blood sugar levels as close to normal as possible significantly reduced the damage to eyes, kidneys, and nerves caused by high blood sugar. The increased risk for heart disease was not significantly reduced by controlling blood sugar levels, but was decreased by lowering blood pressure.

Another recent study found that although it can be expensive to maintain low blood sugar levels, those who do so have significantly fewer doctor and hospital visits and had lower health care costs. (For news about this study, see Recent News below.)

The UKPDT

The UKPDT followed 5,100 Type 2 diabetics for an average of 10 years to find out if significantly lowering blood glucose levels would reduce diabetic complications such as eye, nerve, kidney, or heart disease. Half the people in the trial attempted to keep their blood sugar at or near levels that are normal for the general population. The other half continued with a more traditional treatment plan. Because Type 2 diabetics also have a high risk of heart disease, the study looked at the effects of keeping tight control over blood pressure.

Reducing blood sugar levels significantly reduced complications from eye, nerve, and kidney disease

Overall, the study found that reducing blood sugar levels significantly reduced complications from eye, nerve, and kidney disease. The study also found that by keeping blood pressure at levels recommended for the general population, the risk of stroke and heart failure decreased significantly.

Maintaining tight control over blood sugar was time consuming and costly, and the people in the tight control group had a much higher risk of low blood sugar episodes. (The brain relies exclusively on glucose for energy, so extremely low blood sugar levels can result in tiredness, headache, confusion, or even unconsciousness.) However, because of the significant decrease in diabetic complications, the American Diabetes Association recommends keeping blood sugar and blood pressure levels as close to those of the general population as possible.

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Eye Damage

Of people with Type 2 diabetes, 21 percent already have signs of eye disease (retinopathy) when they are diagnosed, and more than 60 percent develop retinopathy within 20 years. However, the UKPDS found that by maintaining tight control over blood sugar levels, Type 2 diabetics could reduce their risk of eye disease by 25 percent.

Because the retina can be irreversibly damaged before you notice any change in vision, and because retinopathy can be effectively treated with lasers to minimize vision loss, the American Diabetes Association recommends screening for retinopathy yearly.

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Kidney Disease

Kidney disease (nephropathy) is a serious complication that effects about ten percent of people with Type 2 diabetes. In the UKPDS, those who maintained tight control over their blood sugar levels had 25 percent lower risk of developing kidney disease than those on a normal treatment plan.

Because of the serious consequences of kidney disease, the American Diabetes Association recommends screening for protein in the urine every year starting at the time of diagnosis.

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Nerve Disease

Nerve damage (neuropathy) affects 60 percent of all people with diabetes. In the UKPDT, those who maintained tight blood sugar control had 25 percent less risk of developing neuropathy than people following conventional therapy. Nerve damage in the feet can allow small cuts or scratches to go unnoticed, seriously damaging the feet. Because of these consequences, the American Diabetes Association recommends that all people with diabetes have a thorough foot exam every year.

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Heart Disease

People with diabetes have two to four time the risk of developing heart disease or stroke. This risk does not seem to be caused by high blood sugar: In the UKPDT, the group that maintained tight control over their blood sugar still had an increased risk of heart disease. However, the study did find that diabetics who kept strict control over their blood pressure (through medication, diet, and exercise) had a 56 percent lower risk of heart failure and 44 percent lower risk of stroke. For this reason, it is important for Type 2 diabetics to control their blood pressure in addition to their blood glucose levels. (For recent news about excercise reducing heart disease in Type 2 diabetics, see Related News below.)

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Related News

In order to view these articles you will need to have a MyGeneticHealth account. If you are not already a member, selecting the article will automatically take you to a page where you can sign up. Small reduction in blood sugar can lower health costs Exercise reduces heart disease risk among diabetics

References

UK Prospective Diabetes Study Group (1998). Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). Lancet 352: 837Ð853.

American Diabetes Association (1999). Clinical Practice Recommendations 1999 Diabetes Care (Suppl. 1) 22: S1-S114.

Aiello, L., et al. (1998). Diabetic retinopathy (Technical Review). Diabetes Care 21:143Ð156.

National Institute of Diabetes and Digestion and Kidney. (1999). Diabetes Statistics Bethesda, MD; National Institutes of Health. Publication No. 99-3892.

Mayfield JA, et al. (1998). Preventive foot care in people with diabetes (Technical Review) Diabetes Care 21: 2161Ð2177.