Elsevier

Metabolism

Volume 57, Issue 4, April 2008, Pages 511-516
Metabolism

Body mass index status is effective in identifying metabolic syndrome components and insulin resistance in Pacific Island teenagers living in New Zealand

https://doi.org/10.1016/j.metabol.2007.11.013Get rights and content

Abstract

Although adults of Pacific ethnicity living in New Zealand have more than double the prevalence of diabetes and cardiovascular disease than the general population, little is known regarding the presence of risk factors for these disorders among young Pacific Islanders. The study aim was to examine relationships between body composition, glucose and lipid metabolism, and components of the metabolic syndrome (MS) in a community sample of Pacific Island (PI) teenagers living in Dunedin. Anthropometry, body composition (dual-energy x-ray absorptiometry), glucose and lipid metabolism, insulin resistance (homeostasis model assessment [HOMA2], McAuley index), and components of MS were assessed in 80 PI teenagers (aged 15-18 years). Results showed that 6 participants had full MS, 2 had high fasting blood glucose values (>7.0 mmol/L), 55 had high adiposity, and 21 had insulin resistance. Assessment of the components of MS by body mass index (BMI) status showed that obese participants (n = 29) had a high prevalence (86.2% had one or more component), whereas only 10.5% of those with healthy BMI status (n = 19) had any MS component. Elevated fat mass had substantial effects on fasting insulin values, HOMA2, and the McAuley index because in data adjusted for age, sex, and lean mass, a 10% greater fat mass was associated with a 4.7% increase in fasting insulin, a 5.3% rise in HOMA2, and a 2.3% decrease in the McAuley index. Our results suggest that the antecedents of cardiovascular disease and type 2 diabetes mellitus occur frequently in young Pacific Islanders having high adiposity. We conclude that community studies of PI adolescents should focus on assessing risk factors whenever BMI values are high.

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.

Section snippets

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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