If you have IgG and IgM antibodies against insulin, your body reacts as if the insulin is foreign. This may make insulin less effective, or not effective at all. This is because the antibody prevents the insulin from working the right way in your cells. As a result, your blood sugar can be unusually high.
The antibodies can also prolong the effect of insulin by releasing some insulin long after your meal has been absorbed. This can put you at risk for low blood sugar.
If the test shows a high level of IgE antibody against insulin, your body has developed an allergic response to the medication. This could put you at risk for skin reactions at the site of the insulin injection. Or you can develop more severe reactions that affect your blood pressure or breathing.
Other medicines, such as antihistamines or low-dose injectable steroids, may help to lessen the reaction. If reactions have been severe, you may need a treatment process called desensitization.