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December 26, 2006

Fighting Back Against Insulin Resistance
By Kim M. Norton
For The Record
Vol. 18 P. 26 P. 32

Staying active, eating right, and maintaining a manageable weight can help prevent this condition which often serves as a precursor to diabetes.

For years, healthcare providers and public health officials have been warning the public about the power of obesity and the damage it causes. Now, a new concern has emerged that could well overtake obesity as an epidemic: metabolic syndrome, also known as insulin resistance.

Metabolic syndrome is comprised of a series of metabolic risk factors in a particular person. These risk factors, along with genetic predisposition, appear to significantly impact a person’s susceptibility for developing insulin resistance.

The good news about insulin resistance and metabolic syndrome is that early detection and intervention can reduce and eliminate the onset of diabetes and cardiovascular disease, explains Nicola Abate, MD, an endocrinologist at The University of Texas Southwestern Medical Center in Dallas.

Insulin Resistance
“Insulin resistance falls within the metabolic syndrome that is linked to diabetes, hypertension, dyslipidemia, cardiovascular disease, and other blood abnormalities, such as hyperuricemia, elevated levels of plasminogen activator inhibitor-1, and a preponderance of small-size, low-density lipoprotein particles,” according to an American Academy of Physicians article by Goutham Rao, MD, of the University of Pittsburgh Medical Center. “Higher plasminogen activator inhibitor 1 levels and decreased low-density lipoprotein particle diameter are thought to increase the risk of coronary heart disease,” explains Rao.

Research has shown that insulin resistance develops before issues such as diabetes or cardiovascular disease surface, making early detection a preventative benefit to the long-term health of a patient. It is estimated that this syndrome affects 70 to 80 million Americans, according to the American Diabetes Association.

Risk Factors
A person who is obese is at risk for developing type 2 diabetes and cardiovascular disease. Although obesity is a risk factor for insulin resistance, it is important to note that obesity does not implicate insulin resistance, says Abate. Sixty percent of today’s population is obese and, of those, 25% have metabolic abnormalities with insulin resistance—so not every overweight person will have insulin resistance. However, “it is important to evaluate the patient’s risk factors to make an appropriate diagnosis,” Abate says.

According to the American Heart Association, risk factors for metabolic syndrome can include any three of the following:

• increased waist circumference (for men, a waist circumference equal to or greater than 40 inches, and, for women, a waist circumference equal to or greater than 35 inches);

• atherogenic dyslipidemia, blood fat disorders, characterized by high triglycerides (equal to or greater than 150 milligrams per deciliter), low high-density lipoprotein cholesterol (for men, less than 40 milligrams per deciliter, and, for women, less than 50 milligrams per deciliter), and elevated low-density lipoprotein cholesterol;

• blood pressure measured at 130/85 millimeters of mercury or greater;

• insulin resistance or glucose intolerance measured at 100 milligrams per deciliter or greater;

• prothrombotic state (eg, high fibrinogen or plasminogen activator inhibitor-1 in the blood); and

• proinflammatory state (eg, elevated C-reactive protein in the blood).

Other risk factors that contribute to insulin resistance are increased caloric intake, decreased physical activity, and fat distribution, says Abate.

Currently, there is no designated blood test to determine insulin resistance. A complete physical, a thorough blood workup, and an evaluation of genetic history are all necessary to determine a person’s susceptibility. Each of these components can assist in making an accurate diagnosis.

Role of Genetics
When looking at the risk factors, genetic predisposition ranks high in determining who is more susceptible to insulin resistance, explains Abate. “African Americans, Indian, Pakistani, and Bangladeshi people are at the highest risk for developing the metabolic syndrome,” he says.

South Asians, who are generally not overweight, are also genetically predisposed to the syndrome. “Within these ethnic groups, even a mild to moderate increase in weight could translate into a significant problem,” according to Abate.

Factoring in Children
From 1980 to 1999, the 6 to 11 age group experienced a rise in obesity rates from 5% to 14%, according to the Centers for Disease Control and Prevention. To combat this, significant emphasis has been placed on how to increase physical activity in children while reducing junk food in schools. In the Dallas Independent School District, 4% to 6% of school-aged children have type 2 diabetes and an estimated 33,000 children are at risk for developing diabetes, prompting Jon Oden, MD, of Children’s Medical Center in Dallas, to say, “Obesity is an epidemic, but the next epidemic is insulin resistance syndrome.”

Diabetes itself is not a diagnosis of insulin resistance but coupled with obesity, high cholesterol, and genetic predisposition, it is a natural progression for this population. Children at a greater risk of developing diabetes which can lead to insulin resistance exhibit the following characteristics:

• a body mass index greater than the 85th percentile for age and sex;

• a family history of type 2 diabetes in a first- or second-degree relative;

• being of Native American, African American, Latino, Asian American, or Pacific Islander descent;

• signs of insulin resistance or conditions associated with insulin resistance such as acanthosis nigricans, hypertension, dyslipidemia, and polycystic ovary syndrome; and

• a maternal history of diabetes, gestational diabetes, prematurity, and low birth weight with rapid weight gain in the first year of life.

In April, Children’s Medical Center and Oden opened the Insulin Resistance Clinic to screen and treat children who show symptoms of the condition. “Overweight children are at a higher risk of developing diabetes and have the potential for becoming insulin-resistant,” explains Oden.

“The data out there for insulin resistance in children is scarce. Nor do we know what exactly insulin resistance is in children or how to diagnosis it because data available is on insulin resistance in adults. There are no set definitive parameters for insulin resistance in children as of yet,” Abate says. Although there is limited data available for children, insulin resistance is generally a risk that rises with age, but it is becoming more of a concern in the pediatric population, he adds.

Since the clinic opened, 12% of third, fifth, and eighth graders have been diagnosed with acanthosis nigricans—a velvety patch of skin in a high friction area of the body commonly seen in children who are obese—and 20% to 30% are obese. “These children show impaired glucose readings and high cholesterol, which left untreated could develop into diabetes and eventually insulin resistance,” says Oden. Additionally, these children are predisposed to the condition based on their family history and ethnicity.

It is recommended that all children have their blood pressure checked beginning at the age of 3 to closely monitor it to determine whether there is a problem that needs follow-up. Those at risk of developing insulin resistance should have a glucose tolerance test starting at the age of 10 or at the onset of puberty, retesting every two years. Although children at this age do not tend to have high blood pressure, they generally have renal problems due to central hypertension, says Oden.

Reversing the Damage
Just as losing weight can reduce the implications of obesity, the same can be said for insulin resistance. Early detection and prevention are essential when dealing with insulin resistance—be it in an adult or a child. The Western diet has had a tremendous impact on the rise in obesity and insulin resistance, but with proper lifestyle changes, the damaging effects of insulin resistance can be erased, says Abate.

Diet and exercise are strongly suggested to every patient—not only those who are overweight—to reduce the risk of developing diabetes, cardiovascular disease, and insulin resistance. Thirty to 45 minutes per day of brisk exercise and a proper diet free from sodas, junk food, and snacks is recommended. “For every 20 pounds that a person loses, they are significantly reducing their risk of developing insulin resistance,” says Oden.

For some people—specifically those with genetic predisposition—pharmacological intervention may be necessary, but diet and exercise are also recommended. Medications that are available for adults with insulin resistance are not currently recommended for children. In the pediatric population, physicians are limited to prescribing fish oil for high cholesterol and angiotensin-converting enzyme inhibitors for high blood pressure, explains Oden.

It is recommended that children and adults follow a healthy diet and increase physical exercise for six months before being reevaluated. The good news is that significantly reducing waist circumference, cholesterol, and blood pressure minimizes the chances of developing insulin resistance.

— Kim M. Norton is a freelance writer/journalist.

Resources
American Heart Association. Metabolic Syndrome. Available here. Accessed November 13, 2006.

The Centers for Disease Control and Prevention. Available here.

National Diabetes Information Clearinghouse. Diabetes Prevention Program. Available here. Accessed October 25, 2006.

National Diabetes Information Clearinghouse. Insulin Resistance and Pre-Diabetes. Available here. Accessed October 25, 2006.

Rao G. Insulin Resistance Syndrome. American Academy of Family Physicians. March 15, 2001. Available here. Accessed November 8, 2006.

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