Diabetes, insulin and breast cancer

I finished my chemotherapy (Taxotere and Cytoxan 6 rounds) and my radiation. Hooray! My last radiation treatment was a week and a half ago. I did some research and asked for a shorter, higher dose three week course of radiation. They call it the Canadian Protocol. They said that I had very good results and fewer than average side effects.

I called Minimed about using the continuous glucose monitor (CGM) while undergoing radiation therapy. Apparently no one has asked them about this before, so I guess I was test subject #1. They have had people with insulin pumps get radiation therapy but not anyone with a CGM.

The transmitter is very sensitve to radiation, so you need to take it off before you get the radiation. I would disconnect my pump and my CGM transmitter in the car when I parked outside the facility where I got the radiation. 

We were not sure about the sensitivity of the implanted sensor to radiation. Initially, I put the sensor in my thigh to keep it far away from the radiation field. I managed to get a rather impressive bruise when I hit a large blood vessel in my thigh. After some trouble with the insertions of the CGM in the thigh, I called Minimed again and ended up using my lower abdomen. The radiation people put a lead shield over the sensor. The shield might not be necessary, but we were playing it safe since no one has done this before.

After I got the radiation each morning, I would go back to the car, and reconnect everything. You have to re-start and recalibrate the CGM each time after you disconnect the transmitter.  This meant that I would lose data for a couple of hours after each treatment. 

Occasionally the implanted sensor would pull out when I removed the tape. This meant that I went through more than the usual number of sensors each week. Luckily insurance was covering the sensors. Since I generally get more than three days out of each sensor, I had enough extra sensors to  make up for the extra ones that I used during radiation .

The sensors seemed to work well except for when they pulled out from the multiple times I had to remove the tape. I used more insulin during the radiation theapy. I am not sure of this, but it seemed that I needed more basal and bolus insulin in the morning (I got my radiation at 7:30am) and less in the afternoon. the variations in insulin use were not as dramatic as the variations I experienced when I was on the chemotherapy.

 My insulin requirements are going down. They are still higher than before I started treatment, but I am hoping that they will be back to baseline in a few weeks once my body is adjusted to the end of the radiation treatment. 

Carol