Prevalence and Risk Factors of Diabetes and Impaired Fasting
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Khambalia et al. BMC Public Health 2011, 11:719 http://www.biomedcentral.com/1471-2458/11/719 RESEARCHARTICLE Open Access Prevalence and risk factors of diabetes and impaired fasting glucose in Nauru Amina Khambalia1, Philayrath Phongsavan2*, Ben J Smith3, Kieren Keke4, Li Dan5, Andrew Fitzhardinge6 and Adrian E Bauman2 Abstract Background: No comprehensive assessment of diabetes prevalence in Nauru has been conducted since an extreme prevalence was documented more than two decades ago. This study aims to determine the prevalence and risk factors of diabetes and impaired fasting glucose. Methods: A nationwide survey in 2004 of people aged 15- 64 years (n = 1592). Fasting plasma glucose levels were used to defined diabetes (≥7.0 mmol/l or 126 mg/dl) and prediabetes (6.1-6.9 mmol/l or 110-125 mg/dl). Results: The sex-standardized prevalence of diabetes was 13.0% (95% CI: 10.6, 15.4) in men, 14.4% (11.9, 16.9) in women, and 13.7% (12.0, 15.4) combined. The sex-standardized prevalence of prediabetes was 6.4% (4.6, 8.2) for men, 5.5% (3.9, 7.2) for women, and 6.0% (4.8, 7.3) combined. The prevalence of diabetes for individuals 15-24, 25-34, 35-44, 45-54 and 55-64 years was 4.5%, 7.6%, 24.1%, 32.9%, and 42.7%, respectively. The prevalence of prediabetes for the same age categories was 4.2%, 8.8%, 5.9%, 6.6%, 7.1%, respectively. Multivariable, multinomial logit modeling found risk factors for prediabetes were high cholesterol levels (OR: 2.02, 95% CI: 1.66, 2.47) and elevated waist circumference (OR: 1.04, 95% CI: 1.00, 1.08), and for diabetes were age in years (OR: 1.06; 95% CI: 1.04, 1.07), cholesterol levels (OR: 1.84, 95% CI: 1.58, 2.14) and waist circumference (OR: 1.04, 95% CI: 1.02, 1.07). Conclusions: Diabetes remains a major public health problem in Nauru, affecting one out of every ten people. While the prevalence of diabetes has declined, its burden has persisted among the old but also extended towards the younger age groups. Keywords: risk factors, epidemiology, adult diabetes, population studies Background incidence of diabetes in Pima Indians was 38.2 cases/ The prevalence of diabetes in Nauru has previously been 1,000 person-years in 1965, compared to 26.2 cases/1,000 reported to be extremely high. In 1975, the prevalence of person-years in1975/1976-1982 among Nauruans [2,5]. diabetes in Nauru was 34.4%, ranking Nauruans second Explanations for the epidemic proportions of diabetes, in the world for highest ever recorded rate of diabetes heart disease, obesity and hypertension in Nauru include: [1]. The highest rate of diabetes ever recorded in the urbanization, low physical activity, the importation of scientific literature is among the American Pima Indians processed foods and a diabetic genotype [3,6]. After inde- [2]. A 1965 study among American Pima Indians aged pendence in 1968, Nauru became the smallest and richest 35 years and older found age-and sex-specific prevalence republic (per capita) in the world by exploiting large rates ranging from 34.2% to 68.3% [2]. Surveys in Nauru deposits of phosphate [3]. During a period of excessive in 1976 and in 1982 found similarly high rates of dia- wealth, the indigenous population in Nauru, which is betes, with prevalence estimates of 29.0%[3], and 23.9% predominantly of Micronesian ancestry, became more [4], respectively. On an age-standardized basis, the dependent on store-bought food and accustomed to a sedentary lifestyle [6]. The prevalence of diabetes for all age-groups world- * Correspondence: [email protected] 2Sydney School of Public Health, University of Sydney, Sydney, NSW 2006, wide estimated to be 2.8% in 2000 is projected to Australia increase to 4.4% by 2030 [7]. However, Nauru may be Full list of author information is available at the end of the article © 2011 Khambalia et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Khambalia et al. BMC Public Health 2011, 11:719 Page 2 of 10 http://www.biomedcentral.com/1471-2458/11/719 one of the few exceptions in the world where diabetes 2004. Detailed survey methods have been published else- prevalence may actually decrease. A trend analysis of where [8]. the prevalence of non-insulin-dependent diabetes melli- Thesurveywasacollaborativeinitiativebetweenthe tus (NIDDM) and impaired glucose tolerance (IGT) Nauru Ministry of Health, the World Health Organiza- among Nauruans aged 20 years and older showed the tion and the Centre for Physical Activity and Health at age-standardized prevalence (95% CI) of NIDDM the University of Sydney in Australia. Ethics approval was decreased from 27.9% (23.8, 32.0) in 1975/6 to 24.7% granted by the University of Sydney Human Research (22.7, 26.6) in 1982 and then to 24.0% (22.1, 25.9) in Ethics Committee and the Nauru Non-communicable 1987 [5]. The age-standardized prevalence of IGT fell by Disease Steering Committee, Nauru Ministry of Health. more than half from 1982 to 1987 [5]. Results indicate that there was a decline in the incidence of IGT and Data collection NIDDM in subjects with normal glucose at baseline [5]. Behavioral risk factors The study found no changes in the frequency of recog- Information on behavioral risk factors was collected from nized risk factors (physical activity, cigarette smoking, consenting participants using a face-to-face structured obesity, triglycerides or cholesterol), leading the authors interview which included questions on smoking, alcohol to postulate that a high proportion of genetically suscep- consumption, fruit and vegetable consumption, and phy- tible individuals with the ‘thrifty genotype’ had been sical activity [8]. Interviews were conducted in English, removed from the pool [5]. Since these analyses were Nauruan, Kiribati or Tuvaluan by staff trained in the conducted almost two decades ago there has been no interview protocol, and fluent in the local vernacular. further information on the prevalence and risk factors Interviews were conducted inprivateandrangedfrom of diabetes in Nauru. 30-50 minutes in duration. As part of a global effort to address the increasing bur- Anthropometry measurements den of chronic diseases, the Government of Nauru and the Trained survey personnel performed height, weight, World Health Organization in 2004 implemented a blood pressure and waist circumference measurements. nation-wide Stepwise Surveillance of Risk Factors for Height was measured once with a Portable Height Scale Non-communicable Diseases Survey (Nauru-STEPS) to to the nearest 0.1 cm. Weight was measured once to the document the patterns and levels of diabetes and its asso- nearest 0.1 kg with the Seca Scale. Height and weight ciated risk factors [8]. This paper describes the age-specific measurements were taken in light clothing, with shoes, and sex-standardized prevalence of diabetes and impaired socks, and head gear removed. Waist circumference was fasting glycemia (IFG) in a randomly selected and nation- measured once to the nearest 0.1 cm with the Figure ally representative sample of people ages 15-64 years in Finder constant tension tape. Blood pressure (BP) and Nauru and examines the associations between diabetes heart rates were measured with the Omron T5 Auto- and a range of behavioral and biochemical risk factors. matic Blood Pressure Monitor. Both BP and heart rates were measured three times, and the mean value of the Methods second and third readings was used in the analysis. Study setting and design Quality control for each measurement was monitored Nauru is situated in the Central Pacific Ocean. Only 21 through periodic checks conducted by the survey square kilometers (8.1 square miles) in size, Nauru is one supervisor. of the smallest nations in the world. The country consists Laboratory analysis of one main island, divided into 14 small districts. Indigen- A whole blood sample was collected into separate vacu- ous Nauruans, Kiribati and Tuvaluan residents comprise tainer collection tubes for blood lipid and glucose ana- approximately 90% of the total population of around lyses. Venous EDTA plasma blood lipids and glucose 11,000 [9], and were included in the survey. Expatriate were tested on site within 2 hours of collection using a residents were excluded, as well as individuals with mental Reflotron biochemical analyzer (Roche Reflotron Meter). illness, physical or developmental disabilities. When presenting at the blood collection laboratory, all Data from the Birth, Deaths, Marriages Register, Hospi- participants were asked about their fasting status. Partici- tal Medical Record Register, 2003 Electoral Roll, and pants who had not fasted for at least 8 hours were asked Nauru Phosphate Corporate database were used to create to return the next day after fasting. Details on the labora- a sampling frame. A simple random sampling technique, tory analysis have been published elsewhere [8]. stratified by age and sex was then employed. Survey staff Definitions of diabetes visited the randomly selected participants at their homes Diabetes was defined as a fasting plasma glucose value to invite them to participate and to attend the health ≥7.0 mmol/l (126 mg/dl) or a previous diagnosis of dia- clinic for interviews, biochemical and physical measure- betes [10]. Diabetes was further sub classified as “known ments. Data collection occurred from June to October diabetes” if diabetes had been diagnosed previously by a Khambalia et al. BMC Public Health 2011, 11:719 Page 3 of 10 http://www.biomedcentral.com/1471-2458/11/719 medical practitioner or as “newly diagnosed diabetes” if in the analyses for age (p = 0.10), sex (p = 0.32), educa- diabetes was first diagnosed by this study.