Post gym high readings

It's probably the weights. It's certainly not uncommon for weight lifting to cause a blood sugar increase - it's because it's anaerobic exercise, that kind of exercise causes stress and the body to release stress hormones that are counter regulatory to insulin. Lots of people will bolus for weight lifting, or use an increased temporary basal. You might also consider doing your work out the other way round: weights to rise first, cardio to bring you down after.

Go cautious with correcting for spikes caused by exercise, because once those stress hormones dissipate you might drop like a stone because you've still done exercise that might make you more insulin sensitive and have use up some of your glucose stores which your body will be trying to replace before rising blood sugar. It's a tricky balance.

Hi there, it's very common for your bg to be high after weight training, when you start to exercise your liver kicks out some glucose to help with the effort, if there isn't the right amount of insulin at the right time to use that glucose then that's why it can be elevated for a few hours, exercise is very complex, just make sure you keep an eye on your levels later on incase of any unexpected hypos! I have had this happen in the middle of exercise before as well as having high bg after exercise

I am type 2 with no medication, only diet control. I also have high readings after exercise of 12.3. Not really sure how I can change this. It's so complicated. I had a salad prior to gym (low carbs). I I did an hour's cardio. Should this not lower my reading?

If you're serious about exercise (which it sounds like you are) I would recommend getting the diabetic athletes handbook. It has sections for all types. I found it very helpful! I would also recommend caution correcting exercise highs as you can get reactions to exercise hours or a day later. Also if your body has hit burning carbs by oxygen taking energy to your muscles your post exercise meal may not require as much bolus insulin. A fairly hard burst of cardio will push your bg up as when your heart beats relatively fast your body will release it's glycogen stores from the liver. I am no expert but there are many books etc that will help you! It's certainly a learning curve but I have a sort of 'plan' for most exercising. I'm getting better with longer runs now but that was a hard hill to climb (no pun intended)