I am not a doctor so would be reluctant to advise your dosage.
However, this would not be possible with only one reading a day.
The purpose of the basal (Tresiba) is to keep your BG stable.
If it was about 13 before you went to bed, it is probably ok.
If it was 20 before you went to bed, it is probably too much.
If it was 5 before you went to bed, it is probably too little.
Hello @Boozon It's only your DSN who can decide at this stage what adjustments need to be made to your current regime, ongoing you will develop your knowledge and hopefully attend NHS course which will help empower you to make these decisions without any help.
Chase your DSN as it's best to keep on top of this and as Helen has said you will need to see a few days of regular patterns to be better placed to make decisions about adjustments, going off one day doesn't give you enough information or patterns to make any adjustments.
From my experience, your basal insulin is probably about right at the moment*.
Please report back on the feedback from your DSN. As an experienced insulin user, I would be correcting but I don't think I did in my first week.
*You may find your basal dosage could change over time as your BG level reduces. It is common to experience some insulin resistance when your BG gets into the teens or higher.