Extraordinary prevalence of non‐insulin‐dependent diabetes mellitus and bimodal plasma glucose distribution in the Wanigela people of Papua New Guinea

Abstract

Objective To determine the current prevalence of impaired glucose tolerance (IGT) and non‐insulin‐dependent diabetes mellitus (NIDDM) in Melanesians of three coastal Papua New Guinean communities, to relate this to previous studies, and to investigate plasma glucose distributions in these populations. Design Cross‐sectional survey, using 75 g oral glucose tolerance tests and World Health Organization criteria. Setting Rural Papuan villages of Wanigela and Kalo, and Wanigela people of the urban squatter settlement of Koki, Port Moresby. Subjects All adults aged 25 years or more living in the three communities were eligible, with response rates of 77.2% (Koki), 88.1% (Wanigela) and 72.5% (Kalo). Main outcome measures Prevalence of abnormal glucose tolerance, risk factor levels, fasting and two‐hour plasma glucose concentration. Results Age‐standardised prevalence of NIDDM in Koki Wanigelas was 27.5% in men and 33.0% in women; an additional 20.5% of men and 22.0% of women had IGT. Even in the youngest age group (25‐34 years), 36.5% of subjects had abnormal glucose tolerance. The overall prevalences of NIDDM and IGT in rural Wanigelas were 11.7% and 17.0% respectively. In Kalo both were uncommon. The prevalences of IGT and NIDDM in Koki had doubled over a 14‐year period. The age‐standardised prevalence of abnormal glucose tolerance in the Koki Wanigelas is the second highest in the world after the Arizona Pima Indians, and higher than in Micronesian Nauruans, even though the latter are more obese. Both fasting and two‐hour glucose concentrations in all age groups in Koki were clearly bimodal, a mixture of two log‐normal distributions. Conclusions The Wanigela people of Papua New Guinea have an extraordinary susceptibility to glucose intolerance which is exposed after adoption of modern lifestyle habits. A “founder effect” may explain the high frequency of a diabetogenic genotype in this population.

Changes in population cholesterol concentrations and other cardiovascular risk factor levels after five years of the non-communicable disease intervention programme in Mauritius

“…In any case, the overall prevalence of glucose intolerance remains alarmingly high. The increasing prevalence of diabetes reflects similar trends observed recently in other developing17 18 and developed19 populations.…”

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“…While it is possible that the age-adjusted and sex-adjusted prevalence of diabetes in the NCD region at 8.1% reflects lower than expected rates of diabetes, this may also reflect the rapid rate of increase in the disease among young to middle-aged groups. In the urban Wanigela community, diabetes prevalence was greatest in the age group 45–54 years that notably reduced by almost 10% in 65 years and above 12. It has been reported anecdotally that peak mortality due to diabetes in PNG occurs before the age of 50 years, an account supported by the rapid rate of increase in younger age groups and the inverse relationship between age of diabetes onset with complications and mortality 24…”

“…As diabetes prevalence increases with age and is associated with increasing urbanisation,10 we anticipated that the prevalence of diabetes in adults aged 50 years and over in NCD would be closer to the previous estimate, or higher. Previous assessments in the NCD region ranged between 13% (fasting capillary blood glucose ≥7.0 mmol/L in participants aged 12–76 years)11 and 50.5% (fasting plasma glucose ≥7.8 mmol/L and/or 2-hour postchallenge glucose ≥11.1 mmol/L) in adults aged 45–54 years descending from the Wanigela village in rural Central Province and now residing in urban areas 12. The most recent WHO STEPwise approach to Surveillance (STEPS) survey (2007–2008), covering adults aged 55–64 years selected from all four regions of PNG, reported 13.7% diabetes (95% CI 10.2% to 17.2%; fasting capillary blood glucose ≥6.1 mmol/L and/or 2-hour postchallenge glucose ≥11.1 mmol/L) 5.…”

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“…However, no significant differences of age, gender and FPG were observed between the subjects who did participate in the study and those who did not. Finally, some previous studies have included those who were receiving medication [14], [16], [17], and others have excluded them [5], [18]. Excluding those receiving treatment eliminates the treatment effect, but can change the characteristics of the population with diabetes [1].…”