Gluten is a protein (a long-chain amino acid) that is found in cereals like wheat, rye and barley.  These cereals are found in a wide range of processed foods today, including bread, rolls, croissants, pasta, breakfast cereals and beer.  Because gluten is a core component of flour, it is also commonly added to soups, sauces and salad dressings, as well as a whole host of recipes served in restaurants.

By comparison, non-coelic gluten sensitivity (NCGS) is not an autoimmune condition.  Whilst the body is still reacting to gluten, there is no antibody reaction and damage to the small intestine does not occur.  However, NCGS does cause the body to release more of a protein called zonulin, which can break down the gut lining anyway and cause leaky gut syndrome (see an excellent explanation here).  This is particularly important for Type 1 Diabetes because it has been found in recent years that this increased gut permeability allows gluten to cross the intestinal barrier.  These gluten peptides then may induce stress in the insulin-producing beta cells of the pancreas and therefore put more pressure on these cells.  More pressure then leads to faster burnout of the beta cells and thus faster inducement of Type 1 Diabetes.  Indeed, research has shown that following a gluten-free diet during pregnancy reduces the risk of Type 1 Diabetes in offspring.