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Historical Trends

Type 1 Diabetes Incidence and Chemical Production, U.S.

Type 1 diabetes incidence has increased in conjunction with chemical production in the U.S. over the past decades. Incidence rates were low before World War 2 (the range is shown in the bars above 1920), when the widespread use of chemicals began. While "correlation does not prove causation," these trends could be related.

You can click on the image to make it larger.

Chemical production data taken from Neel and Sargis (2011). Diabetes incidence data taken from various studies on type 1 diabetes incidence, included in this PubMed collection.

Type 2 diabetes

The number of people with type 2 diabetes is increasing in every country (International Diabetes Federation Diabetes Atlas, 2013). To see the rise in diabetes (and obesity) around the globe since 1980, visit this online graphic from the Washington Post. In the U.S., the latest data show that the prevalence of type 2 diabetes increased by over 30% in youth between 2001 and 2009 (Dabelea et al. 2014).

Type 1 diabetes

Worldwide, the incidence of type 1 diabetes increased, on average, 3% per year between 1960 to 1996 in children under age 15 (Onkamo et al. 1999). Between 1990 and 1999, the worldwide average rate of incidence increase in children under 15 was 2.8%, reaching 3.4% during the 1995-1999 time period. Incidence increased in most continents, with a rise of 5.3% in North America , 4% in Asia, and 3.2% in Europe. This trend is especially troubling in the youngest children; from 1990-1999, for every hundred thousand children under age 5, 4% more were diagnosed every year, on average, worldwide (Diamond Project Group 2006). 

In the U.S., the latest data show that the prevalence of type 1 diabetes increased by 21% in children between 2001 and 2009 (Dabelea et al. 2014), and the incidence of type 1 diabetes in non-Hispanic whites increased by 2.7% per year between 2002 and 2009 (Lawrence et al. 2014).

Can genes alone explain the increasing incidence?

No.

Essentially all researchers agree that changes of this magnitude cannot be explained by genetic changes alone. In fact, studies are finding that high risk susceptibility genes for type 1 diabetes are becoming less frequent over time in children, while more children with low to moderate risk genes are developing the disease more now than in years past (Vehik et al. 2008; Steck et al. 2011). An interesting study from Poland analyzed susceptibility genes from exhumed skeletons from the Middle Ages, and found that genetic predisposition to type 1 diabetes is lower today than it was 700 years ago (Witas et al. 2010).

It is also clear that the trend varies by year and by location, implying environmental factors are critical. The rates of increase are not uniform within Europe or within countries, suggesting that different risk factors vary over time in different countries (Patterson et al. 2012).

Type 2 Diabetes Prevalence and Chemical Production, U.S.

T2D and chemicals

Data and graphic from Neel and Sargis (2011), published by the American Diabetes Association. The data includes both type 1 and type 2 diabetes, but since type 1 is much less common than type 2, the numbers are generally representative of type 2 diabetes.

When did the incidence start to rise?

Around World War 2, in developed countries, but more recently in later developing countries.

The incidence of type 1 diabetes has been rising in children since about the mid-20th century in many European and North American countries (Gale 2002). What has changed during this time period? A number of things changed that may influence the development of type 1 diabetes, including: breastfeeding rates, diet, height and weight, vitamin D levels, infectious disease, vaccines, earlier puberty, factors relating to gestation and birth, and more. A major change that has garnered less attention in studies of type 1 diabetes is environmental chemicals. Yet perhaps we should pay attention: the historical patterns of contamination are consistent with historical patterns of type 1 diabetes incidence. While correlation is not the same as causation, the pattern is certainly consistent. 

The rise in type 1 diabetes incidence is coincidental with the large-scale production and use of many industrial and agricultural chemicals. Like the rising incidence of type 1 diabetes, large-scale chemical production also began around the middle of the 20th century. In 1975 about 60,000 chemicals were manufactured or processed in the U.S.; in 1997 there were over 75,000 (Endocrine Disruptor Screening and Testing Advisory Committee (1998) Final Report U.S. EPA). Chemical production increased during this time as well.

Is the increasing type 1 diabetes incidence leveling off?

Maybe, depending on where you live, but it is not clear yet.

A study from Sweden provides some hope that the trend is leveling off: it found that incidence was increasing in children born through the year 2000, but after that the trend might be flattening. It is too early to say whether this is in fact the case, or just a blip in the data (Berhan et al. 2011). Data from Norway show that the rising incidence has essentially leveled off since 2004 (Skirvarhaug et al. 2014). Data from Sardinia, Italy, also show that the increase is starting to level off in more recent years (through 2009) (Bruno et al. 2013).

Data from Finland, however, show that type 1 incidence appears to be increasing even more rapidly since the mid-1990s than in earlier decades (Harjutsalo et al. 2008). Data from China show that the prevalence of childhood diabetes is rapidly starting to increase (Fu et al. 2013).

Western Australian data shows an interesting cyclical trend, with incidence on average rising overall, but with incidence rising or falling in approximately 5 year cycles (from 1985-2010) (Haynes et al. 2012).

And, data from the U.S. show that as of 2000-2004, incidence of type 1 (and type 2) diabetes in children was still increasing significantly, and has been since the 1980s (in both Philadelphia Lipman et al. 2013, and Colorado Vehik et al. 2007). (See chart above for other U.S. data as well).

It also appears that type 1 diabetes is progressing faster than before. A large study from the U.S. and Europe found that disease progression seems to have increased over the past 27 years in children newly diagnosed with type 1 diabetes (Max Andersen et al. 2014).

In China, meanwhile, the incidence of type 1 diabetes is skyrocketing. Between 1997-2011, type 1 diabetes incidence increased 14.2% per year (!) in Shanghai's children. At that rate, the incidence of type 1 will double in just four years (between 2016 and 2020), and prevalence will sextuple by 2025 (Zhao et al. 2014).

Type 1 diabetes incidence is increasing in at least 61 countries or regions worldwide

I have been making a list of countries/regions that have documented increases in type 1 diabetes published in scientific journals. These include:

Algeria, Argentina, Australia, Austria, Belarus, Belgium, Bosnia and Herzegovinia, Brazil, Bulgaria, Canada, Chile, China, Colombia, Croatia, Cyprus, Czech Republic, Denmark, Dominican Republic, Egypt, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Israel, Italy, Japan, Jordan, Kuwait, Latvia, Libya, Lithuania, Luxembourg, Macedonia, Malta, Mexico, Netherlands, New Zealand, Norway, Peru, Poland, Portugal, Romania, Russia, Saudi Arabia, Singapore, Slovak Republic, Slovenia, Spain, Sweden, Switzerland, Taiwan, Thailand, Tunisia, Turkey, United Kingdom, United States of America, Uruguay, U.S. Virgin Islands.

References

To download or see a list of all the references cited on this page (and many additional references, for example from all of the countries/regions listed above), see the collection Diabetes incidence and prevalence in Pubmed.

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