Ask Joslin: About Insulin

ask joslin featured imageWhere can I inject insulin?

Insulin should be injected into fatty tissue.  Our bodies have a variety of places for fat storage, but only a few of these places have been investigated for safety and rate of insulin absorption.  The four areas you can inject insulin are the abdomen, the back of the arms, the upper side of the thigh and the upper part of the buttocks.  The fastest insulin absorption is the abdomen followed by the arms, buttocks and thighs. You should avoid injecting into any area in these places that have scars, hardened or “lumpy” feeling tissue.

If I use insulin will my pancreas get lazy?

This question makes perfect sense.  After all, ophthalmologist treat amblyopia (lazy eye) by putting a patch over the good eye so the lazy eye will get a workout. You might think that injecting insulin would stop the pancreas from making its own insulin.   But in this case, it just isn’t so.  In fact, doctors use insulin in patients with type 2 diabetes who are glucose toxic (blood glucose is so high that it inhibits normal insulin function) to help the pancreas work better.   In most cases, if you have type 2 diabetes, over time, the beta cells (they make insulin) in the pancreas wear out and additional injected insulin is needed to keep the blood glucose under control.

How do I adjust my insulin injections for medical procedures?

When you are scheduled for a day procedure such as a colonoscopy or outpatient surgery, it is likely that you are not going to be able to eat for at least 12 hours before the procedure and may be asked to follow a clear liquid diet for the previous 24 hours.  The reduction and/or elimination of meals will mean that you need to adjust both oral medications and the amount of insulin you take.   If you take metformin, and your procedure requires you to undergo tests using contrast dye, such as an MRI or CT scan, you will have to eliminate the metformin for 24 hours before and after the procedure.

In general, there is no need to reduce the amount of medicine you take until the day of the procedure unless you are following a clear liquid diet and use one of the incretins: Byetta®, Bydureon® Victoza® or Symlin®.   You can skip taking these if you aren’t eating solid food.

It is the day of the procedure where changes in your usual routine will occur. Oral medicines such as metformin, glipizide, Actos®, Prandin® are withheld until after the procedure when you begin your normal food consumption.  This is because many oral agents can cause hypoglycemia on an empty stomach.   Since non-peaking long-acting insulin (Lantus® or Levemir®) is usually needed to maintain euglycemia during the procedure it is given at its usual dose.  Intermediate-acting (NPH) and mixed dose insulins are usually reduced or skipped, to avoid the potential for hypoglycemia  peaking insulins have when given without food.

The information provided here are general guidelines only.  It is always best to contact your health care provider for specific instructions.


  1. Hello, We have a patient on insulin who is starting chemo for lymphoma.
    Oncologist has patient on prednisone We were wondering if there is a sliding scale for patients taking insulin as well as prednisone?
    Thank you

  2. If insulin is injected into an ABD with 8 inches of fat before muscle, is it absorbed slower than an arm site with 2 inches of fat?? I work in a prison with many obese inmates.

  3. What is the latest on the development of the artificial pancreas? Have clinical trials to date proven successful and if so, can it be rolled out soon?

  4. Has anyone experienced a Humalog Lispro pen cartridge exploding when tin foil on back was being peeled off? I was trying to replace an empty cartridge with a new one from fridge when this happened. Cartridge shattered at top & insulin sprayed out. Glass cartridge cracked in several places.

  5. As a new Type 2 diabetic, Does using insulin result in weight gain? If that is true, won’t the insulin make my condition worse? Instead of better? Has anyone been cured of Type 2 diabetes by using insulin?

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