Doctors need to check patients for diabetes if they even suspect a patient may have the condition, and start using drugs to treat it right away, according to new guidelines released on Wednesday.

An estimated 90 percent of all patients diagnosed with diabetes are not controlling it enough to prevent heart disease and other complications, the experts at the American College of Endocrinology and the American Association of Clinical Endocrinologists said.

At-risk patients, such as the overweight, should start getting screened at 30. If they show poor control of blood sugar, they should go on drugs right away, the two groups said.

“Numerous studies have shown that significant cardiovascular disease develops years before the onset of diabetes,” the groups said in a statement.

A measure of glucose control called A1C should be 6.5 percent or lower, the groups said. Fasting glucose should be 110 or lower and a two-hour glucose challenge test should be 140 or lower.

“Patients with diabetes are often in denial,” said Dr. Jaime Davidson, an endocrinologist at the University of Texas Southwestern Medical School in Dallas and chairman of the guidelines conference.

If a family doctor or primary care doctor suspects a patient may have diabetes, even a young patient, he or she should test immediately, Davidson said.

And a fasting glucose test is no good, he said. The patient should undergo a two-hour glucose challenge to see how well his or her body controls blood sugar.

Insurance companies may balk at paying for the tests, but they shouldn’t, Davidson said.

“It is cheaper to pay for that today than to pay for the first heart attack,” Davidson said in an interview.

The groups acknowledged that diet and exercise can stop a person from becoming diabetic, but said most patients fail.

“Lifestyle is essential. But in the real world it doesn’t really allow us to get a patient to target,” said Dr. Harold Lebovitz of the State University of New York, who chaired the writing committee.

“Doctors have big hearts and patients come to them to say ‘Give me another chance. Give me a diet. Give me another three months,”’ Davidson said.

But he said damage can occur during those three months. “We prefer to get them on target from day one and keep them there,” he said.

Diabetics also need to see their doctors often. “If they are diabetic, one time a year is not enough. Because in that time, something is going to happen.”

An estimated 20 million Americans have type 2 diabetes and one third do not know it, the groups said. Another 41 million have what is known as “pre-diabetes,” which will develop into diabetes if not controlled.

Diabetes costs the economy $132 billion a year, according to the American Diabetes Association.

“Eighty percent of the money spent is not in treating diabetes. Eighty percent of that money is spent in treating complications,” Davidson said.

Drug treatments include metformin, the glitazone or thiazolidinedione class of drugs that includes GlaxoSmithKline’s Avandia, and orlistat *, sold under the brand name Xenical by Roche. Orlistat is a weight loss drug that also appears to prevent progression to diabetes.