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Childhood obesity in a population at high risk for

type 2 diabetes T. Kue Young, MD, PhD, Heather J. Dean, MD, Bertha Flett, and Pauline Wood-Steiman

Objectives: To determine the prevalence of obesity and investigate its association with fasting glucose and insulin among children and adolescents in a population at high risk for type 2 diabetes. Design: A cross-sectional screening survey involving anthropometry and fasting serum levels of glucose and insulin. Setting: A remote aboriginal (Ojibwa-Cree) community in northern Manitoba, Canada. Participants: All children aged 4 to 19 years in the community were invited to participate, with a response rate of 82% (n = 719). Main outcome measures: Obesity is defined as body mass index exceeding the 85th percentile of the National Center for Health Statistics reference data. The diagnosis of diabetes and impaired fasting glucose is based on the new criteria of the American Diabetes Association. Results: There is a high prevalence of obesity, with 64% (female) and 60% (male) exceeding the 85th percentile and 40% (female) and 34% (male) exceeding the 95th percentile. Body mass index is a significant predictor of both glucose and insulin in both sexes, independent of age. Obese children are at increased risk of being classified as having diabetes or impaired fasting glucose (odds ratio 5.1, 95% CI 1.51, 17.0). Conclusions: The early onset of type 2 diabetes in childhood is increasingly observed in many populations. Childhood obesity is a strong risk factor. Early detection and intervention directed at obesity are potential strategies to avert the long-term consequences of type 2 diabetes. (J Pediatr 2000;136:365-9)

The epidemic of type 2 diabetes among many Aboriginal/Native American populations in Canada and the United States during the past several decades

has been recognized for some time.1-3 A more recent development is the rising prevalence among children, associated with a decreasing age of onset. In

From the Department of Community Health Sciences and the Department of Pediatrics and Child Health, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada; and the Island Lake Tribal Council, Winnipeg, Manitoba, Canada. Funding for this study was provided by the National Health Research Development Program of Health Canada (Grant No. 6607-1665-ND). Dr Young is a Senior Scientist of the Medical Research Council of Canada. Submitted for publication Apr 29, 1999; revision received Aug 30, 1999; accepted Oct 1, 1999. Reprint requests: T. Kue Young, Department of Community Health Sciences, University of Manitoba, 750 Bannatyne Ave, Winnipeg, MB, Canada, R3E 0W3. Copyright © 2000 by Mosby, Inc. 0022-3476/2000/$12.00 + 0 9/21/103504 doi:10.1067/mpd.2000.103504

the past decade clinicians have diagnosed this disease in Aboriginal children as young as 7 years of age.4-6 This is a serious concern in view of the increased duration of diabetes and the likelihood of microvascular and macrovascular complications appearing during young adulthood. The cause of the epidemic is not completely understood. Based on studies in adults, obesity has been demonstrated to be one of the most important risk factors for type 2 diabetes.7 It is likely that the emerging pattern and burden of childhood type 2 diabetes is associated with an increasing prevalence of obesity among Aboriginal children. BMI IFG

Body mass index Impaired fasting glucose

We report on a study to determine the prevalence of obesity and its association with metabolic markers of glucose metabolism in a Canadian Aboriginal community known to be at high risk for type 2 diabetes in the adult population. This study was initiated at the request of the community of St Theresa Point in northern Manitoba, whose members have become concerned with the high rate of diabetes in the population and its implications for the future health of their children. A preliminary report on the clinical features of new cases of diabetes detected by screening has been published.5

METHODS Study Setting St Theresa Point First Nation, with a population of 2430, is located 467 km 365

YOUNG ET AL

THE JOURNAL OF PEDIATRICS MARCH 2000 increasing dependence on government subsidies. Storebought food has become predominant in the people’s diet, and the level of physical activity has declined.

Data Collection

Fig 1. Prevalence of obesity by age-sex group based on percentile of National Center for Health Statistics reference population data.

Fig 2. Mean fasting glucose and insulin by age group and sex. by air northeast of Winnipeg, Manitoba, Canada. It is one of 4 communities that make up the Island Lake Tribal Council. In 1875 the Ojibwa-Cree people of the Island Lake area signed Treaty No 5 with the Canadian government. The traditional lifestyle of 366

hunting, trapping, and fishing remained relatively intact well into the 1960s. However, in the decades since then, there has been rapid social change characterized by reduced dependence on the land for subsistence, involvement in the wage economy, and

A project office was established in the school, which had an enrollment of 873 children from nursery school to grade 11 in the 1995 to 1996 and 1996 to 1997 academic years. The children were instructed to arrive at school at 8:00 AM before breakfast on their scheduled day, usually in family groupings. A venous blood sample was taken followed by a nutritious breakfast provided by the project nurse. Standing height was measured with a wallmounted tape, and weight was measured with a standard balance scale. Samples were taken from approximately 5 to 10 children 4 mornings per week between April 1996 and July 1997 except during school holidays. Fasting blood samples were taken to the local health center for centrifuge and storage at 4°C. At the end of each month, samples were packed in dry ice and shipped to the Health Sciences Center in Winnipeg, where they were batched for serum glucose and insulin assays. Children with high fasting glucose levels were referred to the health center for further clinical evaluation by the visiting physician. All results were explained to the parents in person or in writing by the project nurse. Serum glucose was measured with a Hitachi 705 Analyzer and insulin by radioimmunoassay with the Pharmacia kit at the Clinical Chemistry Laboratory of the Health Sciences Center, Winnipeg. This study was approved by the Committee on the Use of Human Subjects in Research of the Faculty of Medicine, University of Manitoba, the Island Lake Diabetes Committee, and the St. Theresa Point First Nation Council. Informed consent was obtained from the parents of all participating children.

YOUNG ET AL

THE JOURNAL OF PEDIATRICS VOLUME 136, NUMBER 3 Table I. Association of fasting glucose and insulin levels with categories of body mass index

Fasting glucose (mmol/L) NCHS percentile Male