Changes in body mass index among Tongan adults in urban and rural areas between the 1970s and 2000s.

The purpose of this study was to determine trends in body physique among Tongan adults, between the late 1970s and the 2000s. Two areas were studied: Kolofo'ou town (as an urban area) and 'Uiha village (as a rural area). Measurements of body weight and height were taken 4 times for all residents in both areas in 1977/79, 1983, 1990, and 2001. The number of the subjects in 1977/1979, 1983, 1990, 2001 were 130, 138, 102, 71 in the urban area and 92, 89, 90, 66 in the rural area respectively. The mean body mass index (BMI, kg/m2) values of males in the rural area increased significantly, from 28.0 kg/m2 in 1977 to 31.0 kg/m2 in 2001 (p=0.001); in females, mean BMI values were 30.6 kg/m2 in 1977 and 33.3 kg/m2 in 2001, this change was not statistically significant. However, the BMI values did not significantly change in males or females in the urban area. The proportion of rural males with a BMI>or=30 kg/m2 had increased from 24.5% in 1977 to 55.5% in 2001 (p=0.012). Although the mean BMI values for males and females were higher in the urban area than in the rural area until 1990, the differences between the two areas were not observed in 2001, due to an increase of BMI in the rural area. Changes of the mean BMI values in the rural and urban areas studied, between the late 1970s and 2000s, were 10% and 4%, respectively.

Identifying cut-points in anthropometric indexes for predicting previously undiagnosed diabetes and cardiovascular risk factors in the Tongan population.

SUMMARY: There is growing concern that a single standard definition of overweight and obesity may not suit all ethnic groups. This study aimed to evaluate different anthropometric cut-points as indicators of risk for Type 2 diabetes (T2DM), hypertension and dyslipidaemia in a cross sectional, representative sample of the population of the Kingdom of Tonga (767 subjects: 314 males, 453 females). Anthropometric measurements included weight, height, waist circumference (WAIST), waist-to-hip ratio (WHR), weight-to-height ratio (WhgtR) and percentage body fat (%fat) using bioelectrical impedance. Risk factors investigated were systolic (sBP) and diastolic blood pressure (dBP), plasma glucose, total cholesterol, HDL cholesterol and triglycerides, hypertension and T2DM. The best predictive cut-points were identified using receiver operating characteristic (ROC) curves. The cut-points identified in this cross-sectional study contrast with those from studies in Caucasian and Asian populations. Optimal cut-points for predicting risk for T2DM, dyslipidaemia and hypertension in men were 29.3-31.7 kg/m(2) for BMI; 98.8-102.9 cm for WAIST; 0.91-0.93 for WHR and 0.56-0.60 for WhgtR. For women, the cut-points were 34.0-35.0 kg/m(2) (BMI), 100.0-102.8 cm (WAIST), 0.83-0.86 (WHR) and 0.60-0.62 (WhgtR). Mean area under the curve (AUC) measurements for each index ranged between 0.57 and 0.75 for men and 0.49 and 0.72 for women. The indexes with the highest AUCs for men were WAIST, WhgtR and BMI; and for women were WAIST and WhgtR. Use of a 100 cm tape for measuring WAIST is recommended as a simple public health and clinical indicator of risk until longitudinal follow-up studies can confirm findings of this study.:

Obesity, Type II diabetes and the Ala54Thr polymorphism of fatty acid binding protein 2 in the Tongan population.

Genetic variation of fatty acid binding protein 2 (FABP2) may contribute to the high prevalence of obesity and Type II diabetes in Tonga. To explore this we assessed the frequency of the FABP2 Ala54Thr polymorphism, obesity, and Type II diabetes in Tongans and possible inter-relationships. We investigated 1022 Tongan subjects, 433 men and 589 women aged 15-85 years, to identify possible associations between the FABP2 Ala54Thr polymorphism, obesity, Type II diabetes, BMI, glucose tolerance and standard lipid variables. The prevalence of the polymorphism was compared with that reported for other ethnic populations (studies from: Japanese, Finnish, African American, Native Canadian and Inuit, Swedish, Guadeloupe Indians, European males, and Caucasian populations). We found that 84% of the Tongan men and 93% of the Tongan women were overweight or obese (BMI> or =25kg/m2). The mean BMI+/-SD was not significantly different among those who were and were not carrying the Thr allele (males: Ala/Ala 30.4+/-5.4 and Thr carriers 29.8+/-5.1; females: Ala/Ala 33.8+/-6.4 and Thr carriers 33.6+/-5.1). The genotype frequencies were 76.2% Ala/Ala, 22.8% Ala/Thr, and 1.0% Thr/Thr. The Alal/Ala frequency is higher than the prevalences reported for all populations studied. The Thr allele was significantly associated with lower total cholesterol and LDL cholesterol in both sexes and in women also with lower HDL cholesterol. We conclude that there is a high prevalence of the FABP2 Ala54Thr polymorphism in Tongans. The polymorphism may be involved in lipid metabolism as the Thr allele is associated with low total and LDL cholesterol levels in this population.

A 45-bp insertion/deletion polymorphism of uncoupling protein 2 in relation to obesity in Tongans.

We compared the current prevalence of increased BMI and type 2 diabetes in a representative group of Tongan subjects with measurements made in 1973, and we determined the distribution and possible interrelations with the UCP2 insertion/deletion (ins/del) polymorphism of these variables. We documented the BMI, glucose tolerance, and standard lipid variables in 1012 Tongan subjects (429 men and 583 women, ages 15 to 85 years) during 1998 and 2000 and compared the BMI findings with those of the 1973 survey. We also genotyped for the UCP2 ins/del polymorphism, assessed its association with obesity and type 2 diabetes, and compared its prevalence with those reported for other ethnic populations. The mean BMI +/- SD was greatly increased in both men (30.2 +/- 5.4 kg/m(2)) and women (33.8 +/- 6.2 kg/m(2)), representing increases since 1973 of 11.9% and 19.4%, respectively. The genotype frequencies were 97% for the del/del genotype and 3% for the ins/del genotype; we found no ins/ins homozygotes. This distribution is strikingly different from those reported for white, South Indian, Pima Native-American, and Asian populations (49 to 77% for del/del genotype). We conclude that there is a marked prevalence of obesity in Tonga, a prevalence that has increased since 1973. We also conclude that there is a unique, near-uniform distribution of the UCP2 45-bp ins/del polymorphism in Tongans. This may be the result of a founder effect and may be relevant to the prevalence of obesity and type 2 diabetes in Tonga.

Obesity, Type II diabetes and the beta 2 adrenoceptor gene Gln27Glu polymorphism in the Tongan population.

As there is a high prevalence of obesity in Tonga, we aimed to determine the distribution of the beta2 adrenoceptor gene Gln(27)Glu polymorphism and to assess its relevance to obesity and to Type II diabetes, known to be prevalent in that population. A random sample of 1022 individuals from Tonga were genotyped for the Gln(27)Glu polymorphism in the beta 2 adrenoceptor gene. To assess the prevalence of obesity we measured body-mass index (BMI), fat-free mass, percentage fat and waist-to-hip ratio (WHR). To assess glucose metabolism we measured HbA(1c), fasting blood glucose, fasting serum insulin, and 1- and 2-h glucose; we also measured serum lipid and creatinine levels. We found that 84% of the Tongan men and 93% of the women were overweight or obese (BMI > or = 25 kg/m(2)) and 15.1% had Type II diabetes. Genotype frequencies among the 1022 Tongans were: Gln/Gln 90.3% and Gln/Glu 9.6%; we found one Glu/Glu homozygote. The mean BMI (+/-S.D.) for men was not significantly different for those who were homozygous (30.2+/-5.4 kg/m(2)) or heterozygous (30.1+/-5.5 kg/m(2)) for the Gln allele; this was also true for women (33.7+/-6.2 kg/m(2) for homozygous and 34.0+/-5.6 kg/m(2) for heterozygous). The Glu allele was not associated with other measures of obesity or abnormal glucose metabolism in this generally overweight population. There is a unique frequency of the Gln/Glu beta 2 adrenoceptor polymorphism among Tongans. We found no association of the polymorphism with obesity measures or Type II diabetes-related variables in the Tongan population among whom we documented a high prevalence of obesity and Type II diabetes and a low frequency of the Glu allele.

The prevalence of diabetes in the kingdom of Tonga.

OBJECTIVE: To determine the prevalence of diabetes, impaired glucose metabolism, and related risk factors in Tonga. RESEARCH DESIGN AND METHODS: A randomly selected representative national sample of 1,024 people aged >15 years was surveyed. Each participant had fasting blood glucose and HbA(1c) measured. Subjects with a fasting blood glucose >5.0 mmol/l (90 mg/dl) and <11.1 mmol/l (200 mg/dl) or a fasting blood glucose < or =5.0 mmol/l and an HbA(1c) >6.0% and every fifth subject with a fasting blood glucose < or =5.0 mmol/l and a normal HbA(1c) had a 75-g oral glucose tolerance test (OGTT). A total of 472 individuals had an OGTT based on these criteria. Subjects with a fasting blood glucose > or =11.1 mmol/l and an elevated HbA(1c) were diagnosed as having diabetes. RESULTS: The mean age was 41.3 years, and the mean BMI was 32.3 kg/m(2). The age-standardized prevalence of diabetes was 15.1% (CI 12.5-17.6), 12.2% (8.7-15.8) in men and 17.6% (14.0-21.1) in women (NS), of which only 2.1% was previously diagnosed. A total of 75% of people with newly diagnosed diabetes had a fasting plasma glucose > or =7.0 mmol/l (126 mg/dl). The prevalence of impaired glucose tolerance was 9.4% (7.3-11.5) and of impaired fasting glycemia 1.6% (0.7-2.6). Undiagnosed diabetes was significantly associated with increasing age, obesity, hypertension, and a family history of diabetes. CONCLUSIONS: The current prevalence of diabetes in Tonga is 15.1%, of which 80% is undiagnosed. A similar survey in 1973 reported a 7.5% diabetes prevalence, indicating a doubling of diabetes over the past 25 years. In addition, lesser degrees of glucose intolerance are common, and much of the community is overweight