It's no secret that type 1 diabetes is on the rise in children. If current trends continue, new cases in kids younger than 5 could double by 2020.
Below are five hypotheses that explain why. All of them presume that the person has some genetic tendency towards developing type 1 diabetes
1. Too big too fast. The "accelerator hypothesis" theorizes that children who are bigger and grow more quickly are more likely to develop type 1 diabetes.
2. Too little sun. The "sunshine hypothesis" comes from data showing that countries situated closer to the equator have lower rates of type 1 diabetes.
3. Too clean. The "hygiene hypothesis" is the notion that cleanliness — lack of exposure to certain germs and parasites — may increase susceptibility to diseases like diabetes.
4. Too much cow's milk. The "cow's milk hypothesis" states that exposing babies to infant formula containing cow's milk in the first six months of life damages their immune systems, and can trigger autoimmune diseases such as type 1 diabetes.
5. Too much pollution. The "POP hypothesis" alleges that being exposed to pollutants increases diabetes risk.
http://health.usnews.com/health-news/family-health/diabetes/articles/2010/04/26/5-reasons-that-may-explain-why-type-1-diabetes-is-on-the-rise.html