Prevalence, awareness, treatment and control of diabetes in Portugal: Results from the first National Health examination Survey (INSEF 2015)
Introduction
Diabetes Mellitus (DM) is a major public health threat worldwide, reaching epidemic proportions in many developing and in most developed countries. It is a serious chronic metabolic disorder and an important modifiable risk factor for cardiovascular disorders [1]. DM is one of the most common chronic diseases in nearly all countries, and continues to increase in numbers and significance, as economic development and urbanization lead to changing lifestyles characterized by reduced physical activity, and increased obesity [2]. In 2015, the estimated global prevalence of DM was approximately 8.3% [3]. The International Diabetes Federation (IDF) projections predict that in 2035 the prevalence of diabetes will increase to 8.8% worldwide [3]. The burden of ill health due to diabetes has also been increasing, primarily in the developing world. Almost 80% of these deaths occur in low- and middle-income countries, and almost half are people aged under 70 [4]. The increasing prevalence of DM has led to tremendous increases in health care costs, in the treatment of the disease and in the management of DM-related complications. Common complications include both microvascular (neuropathy, nephropathy and retinopathy) and macrovascular (cardiovascular disease, stroke and peripheral vascular disease). Numerous studies have indicated that the burden of DM may be reduced through appropriate interventions. Maintaining blood glucose at a normal level can significantly lower the risk of DM-related complications, delaying disease progression. The estimates of the current prevalence, awareness, treatment and control diabetes are important in order to develop specific intervention strategies and allocate community and health resources, to emphasize the role of lifestyle, and encourage measures to counteract trends for increasing prevalence.
In Portugal, diabetes prevalence has been systematically estimated by Health Interview Surveys (HIS) based on self-reported measures. HIS performed in 2014 reported a diabetes prevalence of 9.3% in individuals who are 15 years old or older [5]. Because a large proportion of diabetes patients are not aware of their condition, these estimates were likely underestimated [6]. To address this issue, a first diabetes prevalence study (PREVADIAB) based on objective measurements of glycemia and of glycated haemoglobin has been performed in Portugal in 2009 [7]. PREVADIAB study, estimated a diabetes prevalence of 11.7% in individuals aged between 20 and 79 years old (95% CI: 10.8–12.6%). Of these, 43.6% were undiagnosed. In addition, a recent study regarding the trends in diabetes incidence from 1992 to 2015 in Portugal, reports an average increase in diabetes incidence rate was in total 4.3% (CI95%: 3.8–4.8) per year under study [8]. Given this information, it was of paramount importance to have updated diabetes estimation on the Portuguese population.
The objective of this study was therefore to estimate the prevalence of diabetes and prediabetes, determine awareness, treatment and control of diabetes and characterize the diabetic population in Portugal.
Section snippets
Research design and methods
The Portuguese National Health Examination Survey (INSEF) is a cross-sectional population-based study developed in 2015 by the National Health Institute Doutor Ricardo Jorge, IP (INSA, IP) in cooperation with the five Regional Health Administrations (RHA), the Regional Health and Social Affairs Offices of the Autonomous Regions of the Azores and Madeira and with the Norwegian Institute of Public Health (NIPH).
Participants’ Characteristics
INSEF survey participation rate was of 43.9%. From the total number of participants (n = 4911), 155 individuals were excluded from this study due to: (1) lack of data on HbA1c measurement (n = 119); (2) pregnant women (n = 31); and (3) lack of questionnaire data regarding the medical diagnosis of diabetes or anti-diabetic medication intake (n = 5). The participants’ characteristics are described in Supplementary Table 1. The final sample size was 4756 individuals, of which 2222 (48.2%) were
Discussion
Our estimates of the prevalence of diabetes (9.9%) were slightly higher than the global estimate (8.8%) and than the estimate for Europe (7.3%) [21]. The INSEF estimates were also higher than the estimates of self-reported diabetes performed by the National Health Interview Survey in 2014 (9.9% vs 8.8%) [22], supporting an important role for Health Surveys with physical examination in which health parameters are objectively measured and not self-reported. However, INSEF point estimate of
Acknowledgement
The authors would like to acknowledge Dr. Lars Christian Stene from the Norwegian Institute of Public Health for kindly reviewing this manuscript.
Funding
The Portuguese National Health Examination Survey 2013–2016 (INSEF) was developed as part of the Pre-defined project of the Public Health Initiatives Program, “Improvement of epidemiological health information to support public health decision and management in Portugal. Towards reduced inequalities, improved health, and bilateral cooperation”, that benefits from a 1.500.000€ Grant from Iceland, Liechtenstein and Norway through the EEA Grants, and from the Portuguese Government (15%).
Conflicts of interest
None.
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