written by Sarah Howard
Coordinator of the Diabetes-Obesity Spectrum Working Group
You may have seen the recent articles about the CDC data that found that type 2 diabetes incidence has recently started to decline in the US (e.g., New diabetes cases, at long last, begin to fall in the United States). That New York Times article notes that, “Type 1 diabetes, often diagnosed in childhood and adolescence and not usually associated with excess body weight, was also included in the data.”
Well, there has been a lot of talk about CDC data relating to type 1 diabetes. While it is technically true that type 1 diabetes is “included” in the CDC numbers, the CDC data do not tell us anything about type 1 diabetes. Since type 2 makes up about 90-95% of diabetes cases in the US, and the CDC does not distinguish between type 1 and type 2 diabetes, the CDC data do not tell us if type 1 is increasing or not.
A new Medpage Today article notes that a new study finds that type 1 prevalence increased between 2002-2013 in US children: Type 1 diabetes prevalence on the rise in kids: group complains about reports that lump type 1 together with type 2 (See the study: Prevalence of diabetes and diabetic nephropathy in a large US commercially insured pediatric population, 2002–2013.)
Type 2 in children increased until 2006 and then began to fall. Thus the two types do not show the same pattern in the population, and should not be lumped together.
This study also finds that diabetic nephropathy is also increasing in children, starting at age 12.
Other data, from the SEARCH for Diabetes in Youth study, also continue to find type 1 increasing in US children.
And almost no one is looking at type 1 incidence in US adults.
NHANES also does not distinguish between type 1 and type 2 diabetes, making it difficult for researchers to analyze whether or not chemicals play a role in type 1 diabetes. Type 1 diabetes is an autoimmune disease that often is diagnosed during childhood. Type 2 diabetes is associated with insulin resistance and obesity. We cannot assume that these separate processes have identical or even similar responses to chemical or other environmental exposures.
Type 1 diabetes incidence in children is increasing in at least 61 countries/regions worldwide. To see these studies or more on diabetes incidence/prevalence in the US and around the world, see Diabetes Incidence and Historical Trends