Prednisone can raise blood sugar levels but I have read it usually happens in people already prone to diabetes (or have it), which you are with your family history. A fasting level of 169 is definitely elevated. 126 is the cut off Ideally you need to have two different tests (glucose tolerence would be one of them, the other an elevated random blood sugar, besides the fasting level) on two different occasions but often doctors go by two abnormal fasting levels. Whether it is caused by drugs or develops on its own, "high blood sugar" is diabetes. While your blood sugar is elevated you are susceptible to the same effects of elevated sugar as a diabetic is.
I was diagnosed with diabetes based on two glucose tolerance tests (my fasting has always been normal) It is only after meals that I have a problem so I can control with diet easily. I used to take starlix (which is a quick acting med that causes your pancreas to release insulin) but once I cut out wheat I no longer need it. Starches can be worse than sugary foods in terms of blood sugar. Pasta, rice, bagels etc.
I had my knee injected with steroid a few years ago and tested my blood sugar that evening and it was 385! In the morning it was 160. A few months later I had my shoulder injected and my blood sugar remained normal.
You should definitely stay on top of this with your family history.
10 years, many tests, 3 gi doctors, Pentasa 1000mg 3x day
diovan, simvastatin,levothyroxine, sertraline, lyrica, methotrexate, down to 2.5mg prednisone and miserable.