People with type 1 diabetes usually cannot discontinue insulin use once they have started. This is because of the very severe deficiency of insulin in this disorder. However, there are a couple of exceptions to this gen- eral rule. First, there is often a brief period of improvement in pancreas function after the initial diagnosis of type 1 diabetes. This so-called “honey- moon period” can last for a few weeks to a couple of years. During this time, the amount of insulin needed to control the blood glucose is much lower and the occasional patient needs none at all. Second, people who have received either a pancreas transplant or a pancreatic islet cell transplant can sometimes stop using insulin. The latter procedure is still considered an experimental therapy. Although they can reduce or eliminate the need for insulin injections, these proce- dures should not be undertaken lightly, because they are associated with a lifelong need for powerful immunosuppressive (antirejection) drugs that can cause serious side effects.
In principle, it is possible for a person with type 2 dia- betes to discontinue insulin once he or she has started it, if the lifestyle factors that led to the worsening of the diabetes can be reversed. Since the overwhelming majority of cases of type 2 diabetes are associated with overweight and lack of exercise, weight reduction and commencement of a regular exercise program will almost always result in significant improvement in glu- cose control and can lead a person on insulin being able to discontinue it. Unfortunately, in our society, it is very difficult for most people with type 2 diabetes to consistently pursue these goals and the majority will remain on insulin once it has been started. Also, it is a normal part of aging for the insulin-secreting cells of the pancreas (beta cells) to show declining function. The rate of this decline may be faster in people with type 2 diabetes. This leads to a need to intensify treat- ment over time and may explain in part why the majority of those who start insulin treatment will not be able to discontinue it without significant deteriora- tion in control of their diabetes.