In the case of gestational diabetes, this type of diabetes is caused during pregnancy, when the body produces more hormones, which can make the cells of the body more resistant to insulin than what is considered to be normal. When this usually happens, the pancreas typically gets involved, and it begins to create more insulin. However, sometimes this is more work than the pancreas can handle, and it just cannot keep up with the body’s need for insulin. During this time, there is not enough glucose within the cells, while too much glucose stays in the bloodstream. This is what causes gestational diabetes.