Intensive insulin therapy: Too risky for type 2 diabetes?

A Mayo Clinic diabetes specialist answers questions about intensive insulin therapy and type 2 diabetes.

Maria Collazo-Clavell, M.D.

Intensive insulin therapy is an aggressive approach to diabetes treatment. In fact, intensive insulin therapy is the cornerstone of diabetes treatment for most people who have type 1 diabetes and some people who have type 2 diabetes. But now researchers are questioning the safety of intensive insulin therapy for type 2 diabetes. Here, Maria Collazo-Clavell, M.D., an endocrinologist specializing in diabetes at Mayo Clinic, Rochester, Minn., answers questions about intensive insulin therapy.

What is intensive insulin therapy?

Intensive insulin therapy is designed to prevent or slow the progression of long-term diabetes complications by keeping your blood sugar level as close to normal as possible. Intensive insulin therapy is recommended for most people who have type 1 diabetes and some people who have type 2 diabetes — but it isn't right for everyone.

If your doctor prescribes intensive insulin therapy, you'll need to closely monitor your blood sugar level and take frequent doses of insulin. You'll also need regular glycated hemoglobin (A1C) tests. The A1C test reflects your average blood sugar level for the past two to three months. With intensive insulin therapy, the goal is an A1C level as close to normal as possible.

The normal A1C range for people without diabetes is 4 percent to 6 percent. An A1C level less than 7 percent is a common target for people who have diabetes.

What do researchers know about intensive insulin therapy?

A study published in the New England Journal of Medicine in February 2008 found that a diabetes treatment plan that included intensive insulin therapy with an A1C level less than 6.5 percent reduced the risk of death overall, as well as death related to cardiovascular disease. Older studies stress specific benefits of tight blood sugar control with an A1C level less than 7.2 percent, such as reduced risk of diabetes-related eye, kidney and nerve complications.

On the flip side, intensive insulin therapy can lead to potentially dangerous episodes of low blood sugar (hypoglycemia). And now researchers for a government-sponsored trial called Action to Control Cardiovascular Risk in Diabetes (ACCORD) point out more serious safety concerns for intensive insulin therapy in type 2 diabetes.

Among 10,000-plus participants in the ACCORD trial, early analysis showed that 257 participants receiving intensive insulin therapy for type 2 diabetes with a target A1C level less than 6 percent had died since the beginning of the trial — compared with 203 participants receiving standard treatment with a target A1C level between 7 percent and 7.9 percent. About half the excess deaths were related to heart disease. Due to the possible risks, in February 2008 researchers halted the part of the trial that required intensive insulin therapy.

How widespread is the concern about intensive insulin therapy?

Participants in the ACCORD trial have type 2 diabetes and are at high risk of heart disease due to factors such as high blood pressure, high cholesterol or obesity. Although the research findings suggest that intensive insulin therapy with a target A1C level less than 6 percent may be detrimental for people who share these characteristics, the risks may not apply to everyone who has type 2 diabetes.

It's also important to note that the specific reason for the increased death rate is unknown. Preliminary analysis does not link the deaths to low blood sugar episodes or any specific combination of diabetes medications.

Is it safe to continue using intensive insulin therapy?

If intensive insulin therapy is part of your type 2 diabetes treatment plan, continue taking insulin as prescribed until you have the opportunity to talk to your doctor. Although the concerns with intensive insulin therapy and type 2 diabetes shouldn't be taken lightly, the possible risks aren't considered an emergency. Until researchers know more, your doctor may recommend continuing intensive insulin therapy but with a higher target A1C level.

It's also important to remember the other aspects of your diabetes treatment plan. Make healthy eating and physical activity part of your daily routine. Keep your blood pressure and cholesterol under control. If you smoke or use other types of tobacco, ask your doctor to help you quit.

What's the bottom line?

Researchers will continue to study the safety of intensive insulin therapy in people who have type 2 diabetes. In the meantime, the decision about whether intensive insulin therapy is best for you depends on many factors — including your blood sugar level and the presence of any other health problems. Remember, your diabetes treatment plan and target blood sugar level are designed just for you. Carefully follow your doctor's instructions for managing your blood sugar level and reducing your risk of diabetes complications.