Body mass index status is effective in identifying metabolic syndrome components and insulin resistance in Pacific Island teenagers living in New Zealand
Introduction
Although adults of Pacific ethnicity have more than double the prevalence of diabetes (10% vs 4% for the New Zealand [NZ] population) [1], [2], cardiovascular disease (390 per 100 000 vs 176 per 100 000 for the NZ population) [2], [3], and metabolic syndrome (MS) (odds ratio, 2.54; 95% confidence interval [CI], 1.93-3.35) [4] than adult NZ Europeans, little is known regarding the presence of risk factors for these disorders among young Pacific Islanders. This is a concern given the rising prevalence of type 2 diabetes mellitus in overweight adolescents in many populations [5]. Young Pacific Islanders in NZ have extremely high levels of obesity [6]. In a recent representative survey [7], more than 60% of 1429 youngsters aged 5 to 14 years were overweight (males, 33.9%; females, 32.9%) or obese (males, 26.1%; females, 31%) from body mass index (BMI) [8]. Moreover, the prevalence of type 2 diabetes mellitus in adolescents attending Auckland diabetes clinics rose from 1.8% in 1996 to 12.5% in 2002, with all new cases being of Pacific Island (PI) ethnicity [9].
Insulin resistance (IR) generally precedes the onset of diabetes, and a clustering of risk factors known as the metabolic syndrome is independently associated with both type 2 diabetes mellitus and cardiovascular disease [10]. Our study examines the relationships between body composition estimated by dual-energy x-ray absorptiometry, measures of glucose and lipid metabolism, and components of MS in a community sample of PI teenagers living in Dunedin, NZ.
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Materials and methods
The University of Otago Ethics Committee approved the study protocol. Pacific Island volunteers (40 females, 40 males) aged 15 to 18 years were recruited by PI community workers who invited individuals of appropriate age and ethnicity to take part. This sample represents approximately one third of PI teenagers of this age living in Dunedin and was considered representative of the community. After a 10-hour overnight fast, each participant was weighed (electronic scale, Seca Corp, Ontario, CA)
Results
Eighty-three percent of the adolescents invited to take part were enrolled. All participants were of PI ethnicity (Tongan, Samoan, Niuean, Cook Islanders, Tokelauan, Kiribati, or Fijian). Body mass index criteria indicated that 40% were overweight and a further 36% were obese. Eighteen participants weighed >100 kg, and 13 had BMI values >35 kg/m2. Participants with higher BMI values had greater adiposity, higher waist and hip girths, higher fasting insulin and a greater degree of IR, lower HDL
Discussion
In this community sample of PI adolescents, abnormalities of MS and hyperinsulinemia were rare in those having healthy BMI, but common in overweight or obese participants, in agreement with other work [19]. These results suggest that the increased risks of cardiovascular disease and type 2 diabetes mellitus present in adult Pacific Islanders are related to high adiposity, particularly central adiposity, starting in adolescence [20], [21]. All participants with full MS had both high percentage
Acknowledgment
The study was supported by an Otago Research Grant and a Distinguished Researcher Award from the University of Otago.
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