Control your blood sugar levels

Diabetes is on the rise, threatening the hearts of millions of Americans

Last updated: February 2013

The number of people with type 2 diabetes has skyrocketed in recent decades, and so has the number of heart attacks among people who have it. Equally worrisome are the 57 million Americans—roughly a quarter of the people in the U.S.—who have prediabetes. They usually have no symptoms, and most don't even know that their blood sugar is a bit high. But most of them go on to develop full-blown type 2 diabetes. Even if they don't they face an increased risk of a heart attack or stroke, possibly cognitive decline, and certain cancers.

Know your numbers

A fasting blood glucose level (or blood sugar level) above 125 milligrams per deciliter indicates diabetes. And anything over 100 mg/dL is generally considered prediabetes, though some experts say that 110 mg/dL should be the cutoff. But blood sugar levels represent a continuum, and any cutoff point is somewhat arbitrary. In general, the higher your blood sugar level, the greater your risk. And the presence of other risk factors, such as high blood pressure and high LDL (bad) cholesterol, are reasons to take even slightly elevated blood sugar seriously. People who already have diabetes should try to keep their A1C level, which is a marker for long-term blood sugar control, under 7 percent.

The table below lists the A1C levels that most people should aim for. Also shown are the blood pressure and cholesterol levels people should strive for if they have diabetes or prediabetes.

Hemoglobin A1c (HbA1c) Below 7 percent (below 6.5 percent for some)
Blood pressure Below 130/80 mmHg
LDL (bad) cholesterol Below 100 mg/dL (below 70 mg/dL is better)
HDL (good) cholesterol Above 40 mg/dL for men; 50 mg/dL for women
Triglycerides Below 150 mg/dL

Get screened

Adults who are at elevated risk for diabetes should have their blood sugar level measured at least every three to five years. That includes people with a personal history of heart attack, stroke, or heart disease, as well as those with any of these coronary-risk factors: a systolic (upper) blood pressure over 135 mmHg or a diastolic (lower) pressure over 80 mmHg; obesity (with a body mass index of 30 or over); or an LDL (bad) cholesterol over 130 mg/dL. Adults without those risks should also consider screening, though the benefits for them are less certain.

Early symptoms. You should also be tested if you have early symptoms of diabetes, listed below:

  • Extreme thirst
  • Extreme hunger
  • Frequent urination
  • Sores or bruises that heal slowly
  • Dry, itchy skin
  • Unexplained weight loss
  • Blurry vision that changes from day to day
  • Unusual tiredness or drowsiness
  • Tingling or numbness in the hands or feet
  • Frequent or recurring skin, gum, bladder, or vaginal yeast infections

How to test. The gold standard is the oral glucose tolerance test, in which patients drink a sugar solution and have their blood sugar checked several times over the next two hours. But nearly as good and faster is the fasting blood glucose test. For it to be accurate, avoid nonessential drugs and all food and drink, except water, for 9 to 12 hours before. Another test, the hemoglobin A1c, reflects the average blood sugar level over the previous three months. Though some doctors now use it for screening, we think it should be limited to monitoring blood sugar control in people already diagnosed with diabetes.

If you've been told you have diabetes, talk with your doctor about monitoring your blood sugar level at home. And see our Ratings to find the best blood glucose meter.

Start with lifestyle changes

You don't need drugs to prevent diabetes, even if you already have prediabetes. A 2006 review of seven major prevention trials concluded that weight control, staying active, and consuming a heart-healthy diet were more effective than medication in preventing the condition. Those measures help not only by preventing diabetes itself but also by lowering blood pressure and LDL, which pose particular risks to people with elevated blood sugar levels.

Of those three, losing weight might be the most important. Researchers estimate that about 70 percent of the cases of type 2 diabetes stem from too much body fat. And for those who already have the condition, our recent survey about managing type 2 diabetes found that losing weight was particularly important.

Get the right drugs

Since high blood pressure and cholesterol levels are a major concern for people with diabetes or prediabetes, they might be more likely than other people to need drugs for those problems. See our Best Buy Drugs for high blood pressure and statins.

Medication designed to control blood sugar levels can help people who have diabetes prevent certain complications of the disease, such as vision problems and nerve damage, but they have not been found to help prevent heart attacks. Still, your choice of diabetes drugs does have implications for heart health, since recent research suggests that one of those drugs—rosiglitazone (Avandia)—actually increases the risk of a heart attack.

An older and cheaper drug called metformin (Glucophage and generic) is usually the best first choice for people with diabetes. It not only works as well as other drugs but also lowers LDL cholesterol and triglycerides, doesn't seem to cause weight gain, and is less likely to cause a dangerous drop in blood sugar levels.

E-mail Newsletters

FREE e-mail Newsletters!
Choose from cars, safety, health, and more!
Already signed-up?
Manage your newsletters here too.

More From Consumer Reports

The Best Matching Washers and Dryers These washer-dryer pairs cleaned up in Consumer Reports' tests.
Best 4K TVs to Buy Right Now The top picks from the hundreds of 4K TVs we've tested.
Best New Car Deals Save money on the cars that Consumer Reports recommends.
How to Pick the Right Size Generator for Your House Add up the items you need to power before making your choice.


Cars Build & Buy Car Buying Service
Save thousands off MSRP with upfront dealer pricing information and a transparent car buying experience.

See your savings


Mobile Get Ratings on the go and compare
while you shop

Learn more