High blood sugar

Can anyone shed any light on this?
A bit of background. Before cancer I had packed on the weight by eating/drinking too much and exercising too little. (Little did I know that excess weight would soon be a good thing!) I weighed over 190 pounds when I should have been more like 160.
After I had my first of three rounds of Cisplatin, my bloodwork showed that my sugar was well into diabetic level. They surmised it was due to the steroid they'd jacked me up with. They discontinued the steroid and my blood sugar fell back into acceptable range. My other two rounds of Cisplatin, sans steroids, went fine.
Fast forward to post-treatment recuperation. I'd gotten down to about 150 pounds and was looking pretty gaunt. To put on weight I ate a lot of Haagen Dasz. (Hey, it's high in calories and easy on the throat.) I had some routine bloodwork done and my sugar was up into what they call the "prediabetic" range. Doc said, "Lay off the sweet stuff!" Not only did I do that, I changed my diet so I'm living about as low on the glycemic index as one can go.
Six months of clean living go by. I have more routine bloodwork and STILL my sugar is in prediabetic range.
So I decided to hit it with both barrels blazing. I bought an exercise bike and ride that sucker every night. I'm now down to 162 pounds (from about 174 when the last test was taken). I'm hoping my next bloodwork will show my sugar is where it ought to be, because now I've done pretty much everything that a guy can do short of medication.
Which is a long way of getting to my question: Has anyone heard of high blood sugar being a byproduct of Cisplatin, radiation or a combination of the two? I've done a number of Google searches on this topic and found little of value.
Thanks, all.

--Jim in Delaware