Evaluation of the insulin resistance syndrome in 5- to 10-year-old overweight/obese African-American children - Insulin Resistance in Children - Brief Article

Nutrition Research Newsletter, Nov, 2001

The prevalence of overweight and obesity is increasing in children, as is the diagnosis of type 2 diabetes. Obesity and insulin resistance are known risk factors for the development of type 2 diabetes in adults. For adults, type 2 diabetes and obesity are more prevalent in the African-American population than in European-Americans, especially among African-American women. Studies in adults have consistently shown insulin resistance and hyperinsulinemia to be strong predictors of the development of type 2 diabetes. In addition to insulin resistance and beta-cell dysfunction, obesity (specifically central adiposity), dyslipidemia, and genetic predisposition are risk factors for the development of impaired glucose tolerance and type 2 diabetes in adults.

The clustering of insulin resistance, obesity, hypertension, dyslipidemia, and atherosclerosis has been referred to as the insulin resistance syndrome (IRS), the metabolic syndrome, or syndrome X. Increasing rates of type 2 diabetes in the pediatric population suggest the need to explore the development of insulin resistance and other risk factors for type 2 diabetes in childhood. The current study was conducted to further examine the relation between insulin sensitivity and age, pubertal status, family history, and obesity in overweight African-American children.

The data reported in this study were part of a baseline screening of children for entrance into a diabetes prevention study. The goal of the study was to recruit overweight children (>90th percentile of BMI for age and sex) into a randomized clinical trial of interventions for weight modification. Chart reviews were conducted at University of Maryland Medical System-affiliated primary care sites to identify African-American children between 5 and 10 years of age who were above the 90th percentile of weight for height at their last well-child visit within the previous year. Initial screening took place over the telephone. It consisted of questions designed to determine whether the child was believed to be overweight, whether the child had any conditions that would affect his or her ability to benefit from a weight management program, and whether a primary caregiver was available to participate in the program.

Each child had an oral glucose tolerance test (OGTT) and physical examination. Skinfold thickness was measured using calipers in the tricep and subscapular regions by either the study nurse or physician. Data were analyzed for 137 children (51 percent female) who started the OGTT and at least had a fasting insulin and glucose measurement taken.

During the OGTT, older and heavier children produced more insulin in response to the glucose load. One child met the criteria for impaired fasting glucose (fasting glucose >/ =110 and <126 mg/dl). Six children met the criteria for impaired glucose tolerance (120-min glucose >/=140 and <200 mg/dl). None of the children were diagnosed as diabetic as a result of the OGTT. Girls were more insulin resistant than boys, older children more resistant than younger children, and children who were more overweight were more insulin resistant than those children who were less overweight. Girls produced more insulin at all time points, and values for insulin increased with age and weight, regardless of sex. Both measures of insulin sensitivity were significantly correlated with increases in blood pressure, triglycerides, subcutaneous fat, and percentage of total body fat. These associations suggest that a clustering of risk factors is present in these children, although the magnitude of the correlations is modest.

These data shiny that in 5-10-year-old African-American children who are not fully pubertal, overweight status is associated with increased risk of insulin resistance and increased subcutaneous fat and elevations in lipid and blood pressure profiles. Young African-American girls were more insulin resistant than their male counterparts, regardless of weight status, and they produced more insulin in response to a glucose load.

These results provide compelling evidence that overweight African-American children should be monitored for insulin resistance and cardiovascular risk factors early in life, and that this monitoring should occur as part of their ongoing medical care. Girls in particular are at increased risk for the development of insulin resistance at an early age, and they mirror the increased prevalence found in minority women.

D. Young-Hyman, D. Schlundt, L. Herman, F. De Luca, D. Counts. Evaluation of the insulin resistance syndrome in 5- to 10-year-old overweight obese African-American children. Diabetes Care 24(8):1359-1364 (August 2001) [Correspondence: Deborah Young-Hyman, PhD, Room N5E13 UMH. 22 S. Greene St., Baltimore, MD 21201. E-mail: dyoung@umaryland.edu.]