Strict Diabetes Control with Heart Disease Still Under Review

< Jun. 10, 2009 > -- The relationship between tight blood sugar control and the risk of heart trouble is still unclear, even after research involving two large diabetes clinical trials.

Analyses of the two trials were presented this week at the annual meeting of the American Diabetes Association in New Orleans.

The Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial found that a troubling number of deaths seen in a large diabetes trial appears not to have been caused by low blood glucose levels, as originally thought.

The ACCORD trial was shut down early after researchers found a 20 percent increased risk of death among those in the more intensive blood sugar control group. It is still not understood, however, what factors might explain the 451 deaths that occurred in the trial.

Meanwhile, analyses of another trial, the VA Diabetes Trial (VADT), found that intensive blood sugar control that is begun many years after diagnosis may actually do more harm than good when it comes to cardiovascular problems.

Tailor Treatment to Each Patient

Results from both trials suggest that diabetes treatment needs to be tailored to the particular needs and characteristics of each patient.

"Treatment should be individualized," says Dr. William C. Duckworth, VADT co-chair and director of diabetes research at the Carl T. Hayden VA Medical Center in Phoenix. "Type 2 diabetes is an extremely heterogenous disease, so if you treat different populations or different groups within the population you're studying you may get different results."

"We are withholding specific recommendations, but there may be potentially different glucose-control targets for different groups of people," adds Dr. Matthew C. Riddle, member of the ACCORD Glycemia Management Group and professor of medicine at Oregon Health Science University. "If we can objectively identify which individuals fall into which groups, that would be a big step forward."

Tight Glucose Control Needs to Start Earlier

Type 2 diabetes, which affects some 24 million Americans, can result in devastating complications such as kidney disease, amputation, blindness, and heart disease. A common test for measuring blood sugar levels looks at hemoglobin A1C values spread over two to three months.

Research previously presented from the ACCORD trial found that intensive lowering of blood sugar in people with poorly controlled type 2 diabetes did not have a significant effect on reducing cardiovascular events, such as heart attack and stroke. In fact, it appeared to raise the risk of death.

At the time, scientists speculated that the increased mortality risk was due to low blood sugar, but this turned out not to be the case.

Instead, "people who achieved a rapid and sustained reduction of A1C from higher levels at the beginning had the lower risk, and the ones who were unable to rapidly reduce glucose from the beginning had the higher risk," Dr. Riddle explains. In other words, those who struggled to get their glucose under control seem to be at higher risk for heart trouble.

Meanwhile, analyses from the VADT trial indicate that intensive diabetes treatment begun earlier after a diagnosis is more likely to be effective, while intensive treatment started 15 years after diagnosis is more likely to do harm.

Starting rigorous control of blood sugar two decades or more after a diagnosis of diabetes actually increased the risk of cardiovascular problems, at least in the population of this trial, which was mostly older males.

Closer to Normal Blood Sugar is Better

One message researchers see from these results is that tight blood sugar control is not bad overall, which is in line with previous thinking.

"The closer to normal range the better, and that is what we've been recommending all along," says Dr. Helena W. Rodbard, past president of both the American Association of Clinical Endocrinologists and the American College of Endocrinology. "We have to aim for good control, but good control early on."

Always consult your physician for more information.

More About Type 2 Diabetes

Type 2 diabetes is a metabolic disorder resulting from the body's inability to make enough, or to properly use, insulin. It used to be called non-insulin-dependent diabetes mellitus (NIDDM).

Without adequate production or utilization of insulin, the body cannot move blood sugar into the cells. It is a chronic disease that has no known cure. It is the most common type of diabetes.

The exact cause of type 2 diabetes is unknown. However, there does appear to be a genetic factor which causes it to run in families. And, although a person can inherit a tendency to develop type 2 diabetes, it usually takes another factor, such as obesity, to bring on the disease.

Of the 23.6 million Americans with diabetes, 90 percent to 95 percent have type 2 diabetes. One-quarter of those with type 2 diabetes are unaware they have the disease.

People with type 2 diabetes often develop the disease after age 45, but are not aware they have diabetes until severe symptoms occur, or they are treated for one of its serious complications.

Type 2 diabetes is more prevalent among African American, Hispanic/Latino American, and Native Americans.

Type 2 diabetes is nearing epidemic proportions in the US, due to an increased number of older Americans, and a greater prevalence of obesity and a sedentary lifestyle.

Type 2 diabetes may be prevented or delayed by following a program to eliminate or reduce risk factors - particularly losing weight and increasing exercise. Information gathered by the Diabetes Prevention Program, sponsored by the National Institutes of Health (NIH) and the American Diabetes Association, continues to study this possibility.

Untreated or inappropriately-treated diabetes can cause problems with the kidneys, legs, feet, eyes, heart, nerves, and blood flow, which could lead to kidney failure, gangrene, amputation, blindness, or stroke. For these reasons, it is important to follow a strict treatment plan.

Advances in diabetes research have led to improved methods of managing diabetes and treating its complications. However, scientists continue to explore the causes of diabetes and ways to prevent and treat the disorder. Other methods of administering insulin, such as pills, are currently being studied. Scientists are investigating gene involvement in type 1 and type 2 diabetes and some genetic markers for type 1 diabetes have been identified. Pancreas transplants are also being performed.

Always consult your physician for more information.