There are several reasons that could account for the fact that taking
insulin injections can lead to weight gain.

The first reason is that before the person was taking insulin the body
was clearly in an insulin deficient state- meaning that the calories
he or she was eating were being wasted in the urine instead of being
stored in the cells.  Once there’s insulin around, if it’s in the
correct dose, all the nutrients will be stored, which leads to weight
gain.  The insulin is just restoring the normal balance. Just like
with anybody else without diabetes, in order not to gain weight we
have eat less and exercise.

The second reason  is that especially in the case of NPH insulin,
where the peak in insulin action happens without really having much
control over it, many patients will eat more than necessary just to
avoid a hypoglycemia. This weight gain is less drastic with glargine
(Lantus) and it seems that there’s even less weight gain with Detemir
(levemir).

Insulin may intrinsically lead to weight gain beyond what I have
mentioned, but it is not clear by what mechanism this might occur.
If you are having trouble you should consult your physician.

Dr. Mariela Glandt was born in Argentina, received her BA from the University of Pennsylvania, and attended the University of Texas-Houston Medical School. She continued on to a residency in internal medicine at Harvard's Beth Israel Deaconess Hospital in Boston. During residency Dr. Glandt did research on beta cell failure at the Joslin Diabetes Center. She then held an endocrinology fellowship at Columbia Presbyterian Hospital in New York, where her research focused on the reversal of Type I diabetes. Read full bio |