Original researchTrends in diabetes incidence from 1992 to 2015 and projections for 2024: A Portuguese General Practitioner's Network study
Introduction
Diabetes Mellitus (DM) is a chronic disease characterized by high levels of blood glucose, that develops either from the destruction of insulin-producing cells (type 1 diabetes) or when body tissues become resistant to the action of insulin, even in a state of circulating hyperinsulinemia (type 2 diabetes) [1]. Type 1 DM is an auto-immune condition that usually develops in childhood or adolescence, while type 2 DM develops in adulthood and is associated with obesity, physical inactivity and unhealthy diet. The latter represents 90% of the global cases of diabetes [2], [3].
DM is known as a major cause of morbidity and mortality worldwide, being one of the main responsible for the global burden of disease [4]. It is the leading cause of blindness, kidney failure and amputation worldwide [5], and is responsible for causing cardiovascular problems that lead to 50–80% of deaths in people with diabetes [6]. The prevalence of DM in Portugal in 2014 was estimated at 13.1% (10.8% in women and 15.8% in men) [7] and Portugal is known as the European Union country with the highest prevalence of this chronic disease [8].
While prevalence data is updated annually, based on the 2010 PREVADIAB nationwide study [9], and taking into consideration demographic changes, diabetes incidence has garnered less attention as a health indicator. The General Practitioner's (GP) Sentinel Network (GP Sentinel Network) represents, in Portugal, the only data source on diabetes incidence, since 1992 to nowadays.
Thus, this study aimed to gain insight into the DM incidence trends, between 1992 and 2015, in the Portuguese population under observation of the GP Sentinel Network, as well as to make projections for the future incidence rates based on this knowledge.
Section snippets
Methods
GP Sentinel Network is a network based on the volunteer work of General Practice/Family Medicine doctors whose professional activity is developed in primary healthcare centers of the Portuguese National Health System. These doctors report several health events, agreed each year. Between 1992 and 2015 (except 2001 and 2002), family doctors from GP Sentinel Network reported all new cases of DM (both types 1 and 2) in their patients’ lists. Diabetes case definition used was based on
Total and sex stratified incidence
In the first triennium under study, 1992–1994, the annual incidence rate was 261.7/105 inhabitants, and in the last triennium, 2013–2015, was 630.42/105 inhabitants (Fig. 1). Until 1998–2000, the annual incidence rate was higher in women, and from 1998–2000 to 2013–2015 turn out to be higher in men (Fig. 1).
The average increase in DM incidence rate was 4.29% (CI95% 3.80–4.80) per year under study. In men the annual trend was also of increase (5.16% [CI95% 4.47–5.86]) as well as in women,
Discussion
There was an increasing trend in the DM incidence in the time period under study, from 1992 to 2015. We propose that this increase can be related with three main possible reasons that could be acting jointly or individually. On one hand, it could be associated with an increase in the prevalence of obesity in Portugal [15], as obesity is known in the literature as one of the main risk factors for type 2 diabetes [5]. On the other hand, it could also be related with the increasingly pronounced
Conflict of interest
The authors declare no conflicts of interest.
Acknowledgments
The authors thank the volunteer work of General Practice/Family Medicine doctors from the GP Sentinel Network who provided information about incident cases of diabetes in their patients’ lists.
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