By, Lisa Foster-McNulty, MSN, RN, CDE

Site rotation.  You’re told to make sure you do a good job of rotating your injection sites so you don’t develop lipohypertrophy, but what the heck does that mean?  We inject insulin into subcutaneous fatty tissue, and when we repeatedly inject the same spots without giving them ample time to heal, we have trouble.  Thickened scar tissue develops under the surface of the skin, and your diabetes educator may have told you that insulin doesn’t absorb normally from areas affected by lipohypertrophy (LHT). 

According to research published online in Diabetes Care in July 2016, LHT is common in insulin users, but the effect on the insulin’s absorption and action was not clear.  Researchers identified 13 patients who have Type 1 diabetes (T1D) and LHT, which was confirmed by examination as well as by ultrasound.  They did a crossover study and injected 0.15 units/kg of lispro insulin (Humalog) into LHT and normal adipose tissue (NAT).  On one day, participants had two injections each into LHT and NAT.  On another day, one injection per region was given before a standardized mixed meal of 75 gm of carbohydrate.  This was done in randomized order.

Compared to injecting into normal adipose tissue, injecting into an area of lipohypertrophy decreased the absorption and effect of the insulin, and it also increased the variability of the glucose response.  The after meal  blood glucose (BG) levels were 26% higher following injection into an area of LHT, and the peak action of the insulin happened later.  Hypoglycemia, which they defined as BG levels of 50 or less, happened less often when injecting into LHT, but profound hyperglycemia (BG levels of 300 and above) only happened in this study following injections into areas of LHT. 

The researchers concluded that both insulin absorption and action are blunted and more variable following injection into an area of LHT.  The end result is poor after meal BG control. 

Pay attention to your habits.  Make sure, whether you are a pump user or someone who uses Multiple Daily Injections (MDI) that you are in the habit of rotating your sites in an organized way–you need to have a system that you follow.  If you aren’t sure how to do it correctly, ask…we are happy to help.  It’s one more way you can improve your BG control.  And if you already have LHT, we can help you to identify new injection or pump sites that can be used to give the LHT areas a rest.  LHT areas can’t be used again until the tissue becomes normal.    

This is a reminder that what we do on a day to day basis does matter!