When describing the prevalence and trends of diabetes it is not always possible to distinguish between T1D and T2D. In many countries, the registration or surveys do not provide information separately for different types of diabetes. Because of this, in this descriptive epidemiological summary the general term “diabetes” is used in many places.
Diabetes has become one of the main health burdens of the 21st century. About 415 million people aged 20 to 79 years are living with diabetes around the world and 12% of total global health expenditure is found to be spent on it. It has been estimated that one adult out of ten will have diabetes by 2040 (International Diabetes Federation 2015). In 1995, it was estimated that the total number of people with diabetes will reach over 300 million by 2025 and the major change in the number of people with diabetes will be seen in developing countries. Several studies have proven the trustworthiness of these predictions (King et al. 1998). The rise in the prevalence of diabetes observed in low-income and middle-income countries is larger than in high-income countries. It may be due to population growth, aging, change in diet and genetic susceptibility. In Europe, a
reasonably steady trend is observed. Trends in Europe might be explained by better-resourced and utilized health care systems (NCD Risk Factor Collaboration 2016).
2.3.1 Prevalence and trends of T2D
Studies have found that the prevalence of T2D is greatly influenced by socio-demographic factors (Veghari et al. 2010). Age, gender, living area and socio-economic status (SES) are found to have remarkable impact over T2D.
2.3.1.1 Prevalence and trends by age and gender
Age has a great influence on T2D. Chance of the development of T2D increases with age. The most critical demographic change in diabetes globally appears to be the expansion in the proportion of individuals more than 65 years of age (Wild et al. 2004). In spite of the fact that T2D increases with age and is still more common among adults, it is now additionally influencing children (WHO 2016a). Increasing obesity is found to be the reason for this trend (American Diabetes Association 2000). From 1980 to 2014 the prevalence of diabetes has ascended from 4.7% to 8.5% in adults (WHO 2016a).
The gender distribution of T2D has also changed over the time. Increase in T2D has shifted towards men from women. There are around 15.6 million more men living with diabetes in contrast with women (International Diabetes Federation 2015). It is found that men are diagnosed with T2D 3-4 year earlier, even with lower BMI, compared with women. Unhealthy life-styles and the tendency of developing abdominal obesity are said to be the reason behind this phenomenon (Wandell &
Carlsson 2014). Although men are more susceptible to diabetes, there are also an alarming number of women living with diabetes (Wild et al. 2004).
Patients with T2D have also gender difference in mortality. However, this difference varies among regions. In North America and Caribbean and Western Pacific Regions, the mortality rate due to diabetes is higher in men compared with women. On the other hand, scenario is opposite in Africa, Europe, Middle East and North Africa, South-East Asia, and South and Central America Regions (International Diabetes Federation 2015).
2.3.1.2 Prevalence and trends by area
Difference in the prevalence of diabetes has been observed between countries, within regions and between urban and rural areas depending on the urbanization and mechanization level, which affect the lifestyle of the population (Cockram 2000). Differences in diabetes prevalence are observed within the countries also in Europe. For instance, in Germany, variation in the prevalence of T2D is observed from southwest to northeast, the regional standardized prevalence was highest in the east being 12.0% (10.3–13.7%) and lowest in the south being 5.8% (4.9–6.7%). This difference might be explained by the differences in the distribution of risk factors of T2D among the regions (Schipf et al. 2012).
Regional differences in the prevalence of T2D are also found in Finland. A study examined the prevalence of T2D, IGT and IFG among Finnish adults aged between 45 to 64 years within eastern, southwestern and southern Finland (Helsinki-Vantaa region). The study found that the prevalence of any form of abnormal glucose regulation was lowest in the eastern Finland and highest in the Helsinki-Vantaa region (31% vs. 38% in men, respectively, P = 0.004 and 19% vs. 26% in women, P < 0.001). This difference might be due to the differences in lifestyle within an ethnically homogenous population (Yliharsila et al. 2005). A study in England observed regional variation in the prevalence of T2D and found that, at strategic health authority (StHA) level, prevalence of T2D varied from 2.4% in Thames Valley to 4 % in North East London (Congdon 2006). Living in deprived area, individual socioeconomic status and ethnicity may explain the regional difference partially (Maier et al. 2013).
2.3.1.3 Prevalence and trends by Socio-economic status
The prevalence of T2D is shown higher among lower socioeconomic groups especially in high income countries (Agardh et al. 2004, Espelt et al. 2008). Sedentary lifestyle and obesity are suggested to be the reasons for this (Zimmet et al. 2001). A systematic review and meta-analysis was conducted to observe the worldwide associations between T2D incidence and socio-economic position (SEP) which was expressed as educational level, occupation and income. The study found that the overall risk of T2D was associated with low SEP in high, middle and low-income countries (Agardh et al. 2011). A study in Germany analyzed the relation between prevalence of T2D and area deprivation at municipality level. The study found that area deprivation is significantly associated with the prevalence of T2D at municipality level (Grundmann 2014). Access to
health-care services and information, availability of healthy foods and availability of places for exercise, economic opportunities, occupational opportunities and individual lifestyle may be the underlying mechanism by which SEP influence in the development of T2D (Brown et al. 2004).
2.4 Impact of T2D on society