Insulin therapy: Does it cause weight gain?

Weight gain is a common side effect of insulin therapy. There are several potential explanations for this. The best understood of these is that insulin improves the ability of your body to use and store sugar (glucose). When your blood glucose levels are high, your kidneys try to remedy the situation by excreting glucose in your urine. The calories in this glucose have been consumed but not used by the body — so they are lost calories. High blood glucose levels also increase metabolism. Insulin therapy reverses these processes as blood glucose levels return to normal, which can contribute to weight gain.

The best way to prevent weight gain is to reduce your calorie intake and increase your physical activity. Decreasing your insulin dosage without dietary restrictions to control weight can lead to high blood sugar and put you at increased risk of diabetes complications.