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.:

Screening for type 2 diabetes and impaired glucose metabolism: the Australian experience.

OBJECTIVE: To assess the Australian protocol for identifying undiagnosed type 2 diabetes and impaired glucose metabolism. RESEARCH DESIGN AND METHODS: The Australian screening protocol recommends a stepped approach to detecting undiagnosed type 2 diabetes based on assessment of risk status, measurement of fasting plasma glucose (FPG) in individuals at risk, and further testing according to FPG. The performance of and variations to this protocol were assessed in a population-based sample of 10,508 Australians. RESULTS: The protocol had a sensitivity of 79.9%, specificity of 79.9%, and a positive predictive value (PPV) of 13.7% for detecting undiagnosed type 2 diabetes and sensitivity of 51.9% and specificity of 86.7% for detecting impaired glucose tolerance (IGT) or impaired fasting glucose (IFG). To achieve these diagnostic rates, 20.7% of the Australian adult population would require an oral glucose tolerance test (OGTT). Increasing the FPG cut point to 6.1 mmol/l (110 mg/dl) or using HbA(1c) instead of FPG to determine the need for an OGTT in people with risk factors reduced sensitivity, increased specificity and PPV, and reduced the proportion requiring an OGTT. However, each of these protocol variations substantially reduced the detection of IGT or IFG. CONCLUSIONS: The Australian screening protocol identified one new case of diabetes for every 32 people screened, with 4 of 10 people screened requiring FPG measurement and 1 in 5 requiring an OGTT. In addition, 1 in 11 people screened had IGT or IFG. Including HbA(1c) measurement substantially reduced both the number requiring an OGTT and the detection of IGT or IFG.

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