Dave Smith found out he had Type 2 diabetes by accident, after a urine test.

“Whoa, look at the sugar in here,” his doctor told him. Mr. Smith’s blood sugar level was sky high and glucose was spilling into his urine.

That was about nine years ago, and from then on Mr. Smith, like so many with diabetes, became fixated on his blood sugar. His doctor warned him to control it or the consequences could be dire — he could end up blind or lose a leg. His kidneys could fail.

Mr. Smith, a 43-year-old pastor in Fairmont, Minn., tried hard. When dieting did not work, he began counting carbohydrates, taking pills to lower his blood sugar and pricking his finger several times a day to measure his sugar levels. They remained high, so he agreed to add insulin to his already complicated regimen. Blood sugar was always on his mind.

But in focusing entirely on blood sugar, Mr. Smith ended up neglecting the most important treatment for saving lives — lowering the cholesterol level. That protects against heart disease, which eventually kills nearly everyone with diabetes.

He also was missing a second treatment that protects diabetes patients from heart attacks — controlling blood pressure. Mr. Smith assumed everything would be taken care of if he could just lower his blood sugar level.

Blood sugar control is important in diabetes, specialists say. It can help prevent dreaded complications like blindness, amputations and kidney failure. But controlling blood sugar is not enough.

Nearly 73,000 Americans die from diabetes annually, more than from any disease except heart disease, cancer, stroke and pulmonary disease.

Yet, largely because of a misunderstanding of the proper treatment, most patients are not doing even close to what they should to protect themselves. In fact, according to the federal Centers for Disease Control and Prevention, just 7 percent are getting all the treatments they need.

“That, to me, is mind-boggling,” said Dr. Michael Brownlee, director of the JDRF International Center for Diabetic Complications Research at the Albert Einstein College of Medicine in New York. “It makes me ask, What is going on? I can only conclude that people are not aware of their risks and what could be done about them.”

In part, the fault for the missed opportunities to prevent complications and deaths lies with the medical system. Most people who have diabetes are treated by primary care doctors who had just a few hours of instruction on diabetes, while they were in medical school. Then the doctors typically spend just 10 minutes with diabetes patients, far too little for such a complex disease, specialists say.

In part it is the fault of proliferating advertisements for diabetes drugs that emphasize blood sugar control, which is difficult and expensive and has not been proven to save lives.

And in part it is the fault of public health campaigns that give the impression that diabetes is a matter of an out-of-control diet and sedentary lifestyle and the most important way to deal with it is to lose weight.

Most diabetes patients try hard but are unable to control their disease in this way, and most of the time it progresses as years go by, no matter what patients do.

Mr. Smith, like 90 percent of diabetes patients, has Type 2 diabetes, the form that usually arises in adulthood when the insulin-secreting cells of the pancreas cannot keep up with the body’s demand for the hormone. The other form of diabetes, Type 1, is far less common and usually arises in childhood or adolescence when insulin-secreting pancreas cells die.

And, like many diabetes patients, Mr. Smith ended up paying the price for his misconceptions about diabetes. Last year, he had a life-threatening heart attack.

The Heart Disease

Just after returning from church last October, Mr. Smith had a discomforting sensation. Deciding to focus on something else, he went to a local newspaper office where he was weekend editor. But the strange feeling persisted and intensified.

“I felt a pain in my chest,” Mr. Smith recalled. “It wasn’t sharp — it was more of a kind of pressure, a feeling like something is contracting.”

The pain spread, to his neck, along his shoulder, down to his biceps. Mr. Smith, alone and frightened, looked up heart attack symptoms on the American Heart Association’s Web site. They were exactly what he was experiencing.

An hour later, Mr. Smith was at the Mayo Clinic in Rochester, Minn., in the throes of a major heart attack, transported by helicopter while his wife and two young sons frantically drove two and a half hours to be with him. A main artery to his heart was 90 percent blocked. If he had waited to seek help or if his local hospital and doctor had not acted quickly and sent him to the Mayo Clinic, he probably would have died.

Mr. Smith thought his biggest risk from diabetes was blindness or amputations. He never thought about heart disease and had no idea how important it was to control cholesterol levels and blood pressure. He said his doctor had not advised him to take a cholesterol-lowering or blood pressure drug and he did not think he needed them.

Most people with diabetes are equally unaware of the danger that heart disease poses for them.

A recent survey by the American Diabetes Association conducted by RoperASW found that only 18 percent of people with diabetes believed that they were at increased risk for cardiovascular disease.

Yet, said Dr. David Nathan, director of the Diabetes Center at Massachusetts General Hospital, “when you think about it, it’s not the diabetes that kills you, it’s the diabetes causing cardiovascular disease that kills you.”