Ask An Expert: Insulin and Weight Gain

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Ask An Expert: Insulin and Weight Gain

Question:

Does insulin cause weight gain? I started taking insulin in July and gained 15 to 20 pounds in three months.

Answer:

It doesn't seem quite fair, but it's true. Weight gain can cause type 2 diabetes, and treatment for diabetes can cause weight gain. If you think this may put you into a vicious cycle, you are right.

Still, when you consider weight gain and diabetes one piece of the story at a time, it makes some sense. When you gain weight, you become more resistant to the effects of insulin. Insulin can't deliver glucose into your cells very efficiently if you are resistant to it, so glucose accumulates in your blood and spills into your urine. You really must treat diabetes, or you will quickly become dehydrated and ill. But if you treat diabetes with supplements of insulin, your body can store all of that glucose and the calories that come along with it.

Insulin is not the only medicine for diabetes that can lead to weight gain. Any of the medicines that allow your body to produce more insulin (such as glipizide, glyburide, or other medicines in the "sulfonylurea" group) can cause weight gain as well. So can drugs such as rosiglitazone (Avandia) and pioglitazone (Actos). These drugs help your fat cells to respond more sensitively to insulin, and in the process the drugs prevent these cells from wasting to a smaller size.

One medicine that treats diabetes does not result in weight gain. This is metformin (Glucophage). Metformin improves your sensitivity to insulin throughout the body, particularly within your liver. Your liver is a major player in your balance of calories, since it turns into a "bakery" of sorts in between your regular meals, manufacturing extra glucose out of raw ingredients. Metformin prevents you from manufacturing this extra glucose in your liver between meals.

None of the diabetes treatment medicines are bad medicines, even though most of them cause weight gain. Diabetes cannot go without treatment.

There are two other treatments that can improve your diabetes and help you lose weight. The first is exercise, and the second is a reduced-calorie diet. Whether or not you take medicine to control your diabetes, you should keep up good exercise habits and watch the amount that you eat.

Mary Pickett, M.D., is a lecturer for Harvard Medical School and an assistant professor of medicine at Oregon Health & Science University in Portland, OR. At OHSU, she practices general internal medicine and teaches medical residents and students.

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Last updated:	January 24, 2007