Heart disease is the No. 1 killer of Americans, accounting for 29 percent of U.S. deaths. High blood pressure and high cholesterol top the list of risk factors for cardiovascular diseases. According to the Centers For Disease Control and Prevention (CDC), one in three Americans has high blood pressure or hypertension. That's bad news for those who want the best life insurance, because high blood pressure is a major risk factor in developing heart disease, stroke, congestive heart failure and kidney disease.

It's no wonder your life insurance company will want to know about your cholesterol and blood pressure before offering you a policy, but just because your doctor orders you to eat less salt and saturated fat doesn't mean you'll have to pay sky-high life insurance premiums.

Life insurers consider not only your blood pressure and cholesterol in determining premiums, but also your age, weight, whether you smoke and any other risk factors for heart disease you might have. The more risk factors you have, the greater the chance you'll have to pay higher premiums for life insurance.

"If someone has treated and controlled hypertension, it probably won't affect their life insurance application," says Dr. Alison Moy, medical director for Liberty Life Assurance Co. of Boston. "If they're overweight, hypertensive, have high cholesterol and smoke it will affect them — they will pay higher premiums."

If you have high blood pressure but aren't overweight, don't smoke, and have normal cholesterol, you might not get the absolute lowest premiums offered by a life insurer — sometimes called "super preferred" or "preferred plus" classes — but you could still qualify for "preferred" premiums. On the other hand, if you are overweight and have high cholesterol, even if you're a non-smoker with normal blood pressure, you might be offered only "standard" premiums. The more risk factors for heart disease you have, the more you are likely to pay for life insurance.

How high is too high?

Doctors generally recommend keeping your total cholesterol below 200, with low-density lipoprotein (LDL) cholesterol below 100, to stay healthy. If your blood pressure goes above 140 over 90, doctors will have concerns. Even so, life insurers might look at those numbers differently.

"Blood pressure of 140 over 90 is clinically low-level hypertension," says Dr. Jacki Goldstein, vice president and chief medical director for Travelers Life & Annuity. "Life insurers are much more liberal than the clinically accepted definitions."

Acceptable blood pressure and cholesterol levels also depend heavily on your age and gender. Insurers have developed charts against which they match your age, gender, blood pressure and cholesterol to determine whether your hypertension or high cholesterol should be a cause for concern.

How will you know if you're in for problems?

If your physician tells you to start taking medication to get your blood pressure or cholesterol in line, and if you don't follow your doctor's orders, it's a good bet your insurer will charge you higher premiums for life insurance. On the other hand, if your doctor doesn't view your blood pressure or cholesterol as serious enough to warrant medication, it probably won't affect your life insurance application either.

It would be very unusual for you to be charged higher premiums for life insurance if your doctor weren't already aware of problematic blood pressure or cholesterol. "It's generally very obvious to a physician that the condition is not under optimal control," says Goldstein.

Admit to medication

If you are taking medication that has already brought your blood pressure or cholesterol under control, don't worry that it will drive up your life insurance premiums. The medications on the market are very effective at bringing down elevated cholesterol and controlling hypertension, and most insurers care more about your levels when you apply for insurance than how you got them there.

"It all comes down to the levels when you apply for life insurance," says Moy. "If the medications work and you're following your doctor's advice, you can qualify for the best premium classes."

Another point in favor of cholesterol and blood pressure-reducing medications is they tend to have very few negative side effects. This makes life insurers happy, because when the side effects of a medication are worse than the symptoms of a disease, they worry about people going off the medication in the future.

What if your life insurer finds out before you do?

The CDC estimates that about one-third of people with high blood pressure don't know they have it. That means a lot of folks are in for a surprise when they get their life insurance medical exams.

"There's a whole lot of undiagnosed hypertension out there," says Goldstein.

In most cases, you don't feel any symptoms of hypertension or high cholesterol, so it is fairly common for one of these conditions to be uncovered by a life insurance medical exam.

When these exams uncover an unfavorable combination of high blood pressure, high cholesterol, age and/or weight, some life insurers will still offer you a "standard" premium policy, but this will come as an unpleasant shock if you were expecting premiums within the preferred classification.

If you are disqualified from the preferred premium classes, most insurers will send you a letter including the medical information they used to place you in the standard category and encourage you to bring those results to your doctor. Then, if you and your doctor are able to get your blood pressure or cholesterol under better control, you can petition your life insurer to lower your premiums.

"A lot of companies use that letter as an opportunity for patient education — to show how being healthy can save you money," says Moy of Liberty Life.

You might not have to wait very long before making that petition. Some people respond to blood pressure or cholesterol-lowering medication within a few weeks. While life insurers won't be that quick to respond to your improvements, you could qualify for lower premiums in as little as six months to a year after starting treatment.