Do any of these affect sugar readings?

Hello @Steve 007

Yes having a cold/illness does affect your readings, your body produces glucose in response to this so levels tend to run high as a result, you can do corrections if you know how much to take, otherwise call your diabetic nurse for some guidance, as a help here are sick day rules for insulin dependent diabetics:

Lemsip has as ingredients: sucrose, saccharin, and aspartame. Night Nurse has added sugar in the form of pure glucose, with ethanol. Most cough remedies are high in sugar too.

I always need more insulin when I have an illnesses. I am also careful of what medicines I take, avoiding the ones with sugar.
I believed for many years believing the temperature changed my insulin requirements. I am not so sure any more. I think it was more likely due to the changes to my eating habits as the seasons change.
When I reduce my carb intake I obviously need to reduce my bolus amounts. When this carb reduction is maintained then I also need to reduce my basal. I believe that this is because my basal/bolus need to follow a ratio, within some kind of limitations. My basal/bolus ration is usually 50/50. For two days every week, I completely fast and my basal drops from around 12u to 7.5u on the second day of my fast. My blood glucose readings are great on this day. I did fast for five days in a row a few months ago and my basal reduced to 4.5u.